- Recently viewed bulb varieties
- Choice of gladiolus styles
- When to plant gladioli
- How to get early flowers
- Where to plant gladioli
- How to plant gladioli corms
- On-going care of gladioli
- Cutting gladioli for the vase
- Should I lift the gladioli corms in autumn?
- How to lift and store gladiolus corms
- The problem of thrips
- Gladiolus Varieties
- lily bulbs waiting to be planted. See PA Feature GARDENING Late Summer. Picture credit should read: PA Photo/thinkstockphotos. WARNING: This picture must only be used to accompany PA Feature GARDENING Late Summer.
- A Gladioli flower bulb onion. See PA Feature GARDENING Late Summer. Picture credit should read: PA Photo/thinkstockphotos. WARNING: This picture must only be used to accompany PA Feature GARDENING Late Summer.
- A Generic Photo of Begonia bulbs. See PA Feature GARDENING Late Summer. Picture credit should read: PA Photo/thinkstockphotos. WARNING: This picture must only be used to accompany PA Feature GARDENING Late Summer.
- Saving Dahlias: How To Remove And Store Dahlia Tubers
- Tips for Saving Dahlias
- How to Remove and Store Dahlia Tubers
- Storing Dahlia Tubers for Winter
- How To Dig and Store Dahlias For Winter
- 1. When To Dig Up Dahlias
- 2. How To Carefully Dig Up Dahlias Tubers
- 8 Easy Steps to Lifting & Storing Dahlia Tubers
- Why Dig Dahlia Tubers?
- 1. Wait Two Weeks After Frost to Harvest Dahlia Tubers
- 2. Trim Back Your Dahlia Stems
- 3. Dig Your Dahlias
- 4. Rinse Your Dahlia Tubers
- 5. Divide Your Dahlias
- 6. Dust Your Dahlias with Sulfur
- 7. Pack them in Peat Moss
- 8. The Perfect Place to Store Your Dahlias
- Checking on Dahlias Throughout the Winter
- How to overwinter dahlia tubers
- Digging, Dividing, and Storing Tubers
- Step 1: Wait for the First Frost
- Step 2: Dig Up Dahlias
- Step 3: Rinse Off Dirt
- How to Overwinter Dahlias
- How to Dig Up Your Dahlia Tubers
- Packing and Storing Your Dahlias
- What to Do When Spring Arrives
- Oh Those Big, Beautiful Dahlia Blooms
- Do Dahlias Come Back Every Year?
- Preparing Your Dahlia Bulbs For Winter Storage
- Storing Dahlia Bulbs For Winter
- Don’t dig up dahlias for winter! What to do instead….
- How not to dig up dahlias
- But take your anti-slug precautions early
- Some dahlias do really need to be dug up…
- The secrets of growing dahlias…from an expert!
- What you say….
- See it on YouTube
Recently viewed bulb varieties
By Graham Clarke
It was not all that long ago that gladioli were considered old fashioned, and something the Dame Edna would throw into her audiences – and little else. However, rather like the dahlia, in the past few years gladioli have been elevated to the hot spot. A new generation of gardeners are appreciating and valuing them for their colourful flower spikes, which are especially useful for cutting and bringing indoors, and for creating the trendy ‘tropical look’ to beds and borders.
Many allotment gardeners grow their gladioli in straight lines, for ease of cutting, and in this situation the Large-flowering (Grandiflorus) hybrids can look rigid and uninspiring. But, in the garden, if you plant a dozen or more bulbs (actually corms) in bold drifts between ornamental grasses, crocosmia and daylilies, the tall, stately flower spikes of the gladioli will look magnificent in a mid- to late summer border.
Farmer Gracy’s Gladiolus Conundrum
See if you can work out the answer to this question (answer at the bottom of this page):
The Latin name Gladiolus shares its origin with the Roman ‘gladiator’, famous for often mortal combat in the arenas of the Roman Empire. So, understanding this, what has become the English common name for the Gladiolus?
1) Shield rose
2) Chariot grass
3) Gladiator flower
4) Sword lily
For the best look with gladioli I would always plant many corms of the same variety, or several in flower colours that are complementary, unless you are aiming for a less formal ‘cottage garden’ look – the kind of look that I call the ‘fruit salad’ effect, with lots of colour variety. Most gladioli grow to about 1.2m tall, so they generally poke above the herbaceous plants around them, to give the border that ‘wow’ factor.
Gladioli are a favourite with flower show exhibitors and flower arrangers, which is one of the reasons why plant breeders have given us such a good choice of styles and colours.
Choice of gladiolus styles
Over the past hundred years and more, it is thought that some 10,000 Gladiolus cultivars have been bred, or species discovered. Not all of them are available commercially, of course, but it does mean that there are plenty to choose from.
Take your pick from bright colours that are guaranteed to make a statement in your garden, or the romantic pastel shades, including pinkish-grey, that can be used to subtly glam-up your garden.
Some cultivars come as bi-colours, sometimes with picotee edges, or dainty splotches on the lower petals and with contrasting stripes and throats.
If you simply want to use these slim-fit plants to make vertical flashes of colour in between large clumps of herbaceous plants, then choose the Butterfly varieties, which have smaller flowers.
If you want to grow gladioli in pots on the patio, or your garden space is limited, choose Dwarf (Gladiolus nanus) varieties, which are petite and demure, growing to a maximum height of around 60cm, so they don’t need staking or tying up.
The flowers usually bloom early; they are star-like and often with distinctive cerise markings on the petals, surrounded by fans of tall, tapering green foliage. Most are more or less weatherproof, too, and are able to cope with a British winter outdoors, so there will be no need to ‘lift’ the corms in the autumn.
When to plant gladioli
Gladiolus corms take 70 to 100 days to grow and flower, so if growing them for cuttings and bringing indoors, plant a few corms every couple of weeks from late spring to mid-July, to have flowers for cutting through summer to early autumn.
Remember that the earlier the planting, and the longer the growing season, yields the best corms for lifting and replanting the following year.
How to get early flowers
You can get flowers in late May and June, if you plant corms in single layers in deep seed trays, kept really moist, and sited in a warm propagator until roots and a few centimetres of shoots are produced. Then they can be planted outside in late February, in soil that has been warmed under frames or cloches. It is surprising how hardy the plants can prove to be once they have started into growth.
As Gladiolus blooms usually last for about three weeks, and we hope our summers will be longer than that, it’s a good idea to achieve a longer-lasting display by planting corms over several weeks.
Where to plant gladioli
Choose a position that gets a fair amount of direct sun throughout the day. Light shade in the morning or late afternoon will be OK.
Sandy, light soils are best. If you have a heavy, clay soil you can fork coarse grit into the planting area to improve drainage. Or put a layer of grit at the bottom of each planting hole. This stops water collecting around the base of the corm, which will cause it to rot.
Before planting, enrich the soil with a handful of low-nitrogen fertiliser, but be sure to mix the soil and fertiliser well so that you don’t ‘burn’ the corms.
How to plant gladioli corms
Plant the corms quite deep, and I would suggest deeper than most books tell you. I plant mine 15-20cm deep, and 15cm apart. I use a bulb planter but a long trowel will do. Secured deep in the ground, you are less likely to need a stake. Particularly on sandy soils it helps to plant them this deep, so they are well anchored against strong winds. This extra-deep planting does not seem to harm the plants or delay flowering.
On-going care of gladioli
Unless they are growing in amongst other plants, large flowered varieties need individually staking with short canes around 30cm tall.
Keep plants well-watered, throughout the summer but especially early on when the foliage is emerging, as plants tend to be very thirsty at this stage. If we get prolonged dry weather, mulch the soil around the plants to keep it moist.
The flowers open from the bottom of the stem upwards. As soon as the flowers appear, feed them with a high potash liquid tomato feed every two weeks until they start to fade. Remove individual blooms as they fade.
Cutting gladioli for the vase
Choose a spike with just the lowest or first bud opening or in bloom. Other buds must be showing colour if they are to open after picking. Cut the stem as low down as possible, with a pair of secateurs or a sharp knife, but keep as many leaves on the plant as possible, and at least four complete ones.
Should I lift the gladioli corms in autumn?
Most gladiolus are not completely hardy but, if you have a sandy soil, live in a sheltered garden, in the south of Britain, and the corms are planted deeply enough – and you give them a good thick winter mulch of well-rotted compost, they’ll probably survive.
However, be aware that corms overwintered outside under mulch may still perish in a really severe or prolonged winter, and, if they do survive, they will probably come in to growth and flower a little later than those lifted, stored and replanted in spring.
If you do leave your corms in the soil every year, it is a good idea to dig and divide the clumps every three or four years to select the best corms for replanting. Without this, the new cormlets that form on the sides of the gladiolus corms will cause congestion, and the available soil nutrients will have to be shared. The result of this is that you will end up with masses leaf and no flower.
How to lift and store gladiolus corms
Further north, or in cold areas, lift the corms in autumn once the leaves begin to turn yellow. Trim back the leaves to within a few centimetres of the corms, dust with sulphur, then leave to dry for a few weeks. Then brush off the soil and store the corms in mesh bags in a dry, dark frost-free place. Don’t keep the leaves on or hang up bunches to dry, as any remaining damp can cause rots later on in storage.
The problem of thrips
While generally pest- and disease-free, gladioli can be attacked by thrips, also known as thunder bugs. These tiny insects suck the juicy sap from the plant, leaving a silvery appearance, eventually causing the plant to turn brown. Thrips also cause deformed flowers and prevent flower spikes from opening.
When storing the corms from affected plants, cut down and dispose of the top growth (preferably by burning or sending to your local authority green waste centre). The important thing is to destroy and expel it from being anywhere near your corms. Do this before the corms are fully dried, to reduce the number of overwintering thrips, and so reduce the likelihood of infestation next year.
Organic pesticides (based on plant oils and extracts or fatty acids) with contact action may give some control. They include Doff Greenfly and Blackfly Killer and Bayer Bug Free. Chemical systemic sprays, such as Bug Clear Ultra, while not being so good for the environment, are absorbed into the plant tissue so may give better control. Importantly, plants in flower should not be sprayed during the daytime due to the danger to pollinating insects.
Farmer Gracy has selected 34 of the very best cultivars to offer its customers, as well as three mixed collections, so you are spoilt for choice. If I had to choose just a small selection for my garden they would be the following.
Of the Large-flowering (Grandiflorus) types, most years I grow– ‘Espresso’, whose buds really are jet black, in pure silk velvet, opening to a deep burgundy-red.
From left to right: Gladiolus Espresso, Gladiolus Evergreen, Gladiolus Shaka Zulu, Gladiolus Purple Flora
For something a bit different, look out for the fresh green varieties such as ‘Evergreen’. It produces showy, upright spikes of flowers. These are particularly useful for giving garden borders a contemporary look. Half a dozen or so look stunning in a simple white vase or tall glass.
Partner these lime green blooms with other gladiolus varieties with dark velvet-textured flowers. Choose from varieties such as ‘Espresso’, or the deep maroon ‘Shaka Zulu’, or the purple ‘Purple Flora’.
The last one, ‘Purple Flora’, is arguably my all-time favourite cultivar. The buds start as indigo blue, and open out into different shades of purple depending on the light. There are other purples, but they mostly have white petal markings and as the flowers age these becomes more prominent, and dilutes the beauty and richness of the overall spike. You don’t get this problem with ‘Purple Flora’. This variety also grows a little taller than most at 1.5m.
From left to right: Gladiolus Georgette, Gladiolus Prins Claus, Gladiolus Charm, Gladiolus Dancing Doll
Growing up to 75cm are the Butterfly varieties, so-called because when the flowers are open their petals resemble the open wings of a butterfly. My favourites among these are ‘Dancing Doll’ (cream-yellow and bright red) and ‘Georgette’ (bright yellow and orange).
Finally, the Dwarf (or Nanus) gladioli grow to just 60-70cm so they are easy to look after, and suitable for growing in patio pots. They include ‘Prins Claus’ (white and raspberry pink) and ‘Charm’ (candyfloss pink with a white throat), and they should be found a place in any garden.
The answer to the Gladiolus Conundrum: 4) Sword lily. In Latin, gladius means ‘sword’, so a ‘gladiator’ was a person armed with a sword. ‘Gladiolus’ actually means ‘a little sword’, and gets its name from its sword-shaped leaves.
“All about Gladioli Corms”
is a guest blog written by:
Horticultural & Publishing
Consultant at HHPS Ltd
I’m not sure what you mean by “dangerous” – i.e., dangerous to squirrels and other animals, or to small children who are naturally curious and put everything in their mouths? Take a look at a previous entry on our website, “Will our squirrels eat gladiolus buds?”, which highlights that the little critters love to eat the bulbs (as well as buds and flowers).
Of note, gladiolus bulbs (called corms) can cause symptoms that include nausea, vomiting and skin irritation, according to the University of Wisconsin Health Wisconsin Poison Center’s “Common plants – what’s poisonous and what’s not?”. This publication also includes lots of non-toxic plants.
PennState Extension’s “Spring plants that are poisonous to horses, dogs and barn cats” states that gladiolus corms can cause salivation, vomiting, drooling, lethargy and diarrhea in cats and dogs, if ingested.
If by “dangerous” you mean”, risks the winter killing the plant”, gladiolus corms should not be left in the ground year-round, as most varieties are hardy in zones 8a-11. They are usually planted in mid-May through mid-June, so that flowers will bloom through July & August. Once the foliage has been killed off by frost, the corms should be dug up and stored.
If you wish, leave a few corms in the ground over winter as an experiment, chances are they will rot in the cold soil, but some growers indicate that glads can over-winter in the ground, even to zone 5. However, this would not be predictable, so you could be gambling each year that the corms would survive the winter. That being said, mulching the glads could protect them from the winter weather, and if your properties are blanketed with a good (insulating) snow cover, the corms would have a better chance of surviving. The Gladiolus nanus ‘Atom’ is hardy in zones 6-10 (needs thick mulch covering where winters are extreme). It grows to around half the height of the glads most of us are used to.
If you decide against glads, see “Long blooming perennials: a Toronto master gardeners guide “. I have found Geranium ‘Rozanne’ to be super-easy to maintain, while blooming over several months.
See also the Missouri Botanical Garden’s “Perennials for season-long bloom“, which may give you some ideas.
Dahlias may still be blooming, but many other summer bulbs including lilies and gladioli, are now past their peak. So, what can you do to give summer bulbs the best chance of returning in future years?
Some summer-flowering bulbs can be left in the ground – crocosmia corms, for instance, just keep on producing year on year and can become invasive – but many more summer bulbs can’t survive British winters.
The general rule with summer-flowering bulbs is to wait until growth has turned yellow and died down, because leaves that are green are still alive and will be providing the bulb with energy it will need for the winter and to flourish next year.
Dahlias should be left until the growth is blackened by frost in autumn, then the stems trimmed back to about 15cm (6in) before lifting the tubers.
Lift gladioli when the foliage is dying down but before the frost can kill off the corms. If you live in a mild area you can often get away with leaving them outside all year round if the ground is well drained.
Once bulbs have been lifted, you need to clean and dry them for storage. Discard damaged or diseased ones, then clean off the soil, dead foliage and any loose skin from the healthy bulbs. Place them on a wire mesh rack, not touching each other, and leave them in a cool, dry, airy place to finish drying.
Dahlias can be hung up in nets in the roof of your shed or garage, or stored in stacking trays with lots of holes in the sides for air circulation.
In mild areas with well-drained soil, you can risk leaving dahlia tubers in the ground in winter. Cut the tops down and cover the area with a 10cm (4in) layer of organic mulch, bark chippings or gravel, for extra insulation.
To prevent disease during the winter, dust lifted summer bulbs with a fungicide and pack them in clearly labelled paper bags, storing them in a cool, dry, airy spot until it’s time to plant them out again. Other bulbs that need to be lifted for over-wintering include begonia, freesia and eucomis.
Lilies in the ground shouldn’t need lifting, although if we have a particularly wet winter they may die off because they don’t like wet feet while they’re dormant. If you have clay soil or poor drainage you may be better off growing them in pots and moving them under cover.
If you are growing them in pots, once blooms have faded, cut off the flower heads, removing the developing seed capsules, but leave the stems. Water and feed regularly to build the bulbs up for next year, either using a liquid feed or a controlled-release granular fertiliser. The stems will naturally die in late summer or autumn and the bulbs can be left in the pots for three or four seasons. After this, plant the whole clump in the border. Don’t leave them out of the soil for long as the bulbs will dry out.
Cannas add an exotic touch to the garden, their deep green waxy leaves revealing scorching red-orange and yellow flowers. They are often grown in pots and in mild areas can be left outside in a sunny, sheltered position, with the addition of a 15cm (6in) layer of mulch in winter. Be prepared, however, for losses in an extremely cold or wet winter.
In colder areas, pot-grown plants should be moved into a frost-free place, or alternatively lift the rhizomes (creeping roots) once top growth begins to droop in the autumn, cut down the foliage and stems to around 15cm (6in), remove surplus soil, dry and store in trays in multi-purpose compost in a cool, frost-free position over winter.
BEST OF THE BUNCH – Rudbeckia
These bright and cheery yellow daisy-flowered showstoppers with chocolate centres come into their own in late summer through to October, complementing fiery displays matched by red hot pokers or crocosmias, or in containers with purple cordyline. Many grow to around 60cm (2ft) but there are taller varieties such as R. ‘Herbstsonne’ (‘Autumn Sun’), growing to 180cm (72in) which looks great at the back of a border in front of late-flowering clematis. They will grow almost anywhere in full sun and reasonably fertile, moist soil. Good varieties include R. fulgida sullivanti ‘Goldsturm’, which produces a profusion of flowers, and the double-flowered ‘Goldquelle’, which grows to around 70cm and looks a bit like a zinnia.
GOOD ENOUGH TO EAT – Harvesting onions
You should be harvesting your onions now, but you’ll know they’re ready when the foliage collapses. Many gardeners recommend that you bend over the tops of onions to ripen them, but this usually happens naturally so you shouldn’t need to intervene. Pick a dry day to dig them up, gently easing the onions out of the ground with a fork, to break the roots’ hold on the soil. Onions need to be dry when stored so if it’s fine, leave the bulbs on the soil to dry off for about a week. If not, cover them with cloches or a sheet of polythene, or lay them out in a cool, airy shed. Once they are dry, bundle them into nets to hang up in the shed, where they will keep best in the light.
Saving Dahlias: How To Remove And Store Dahlia Tubers
Dahlias are a breeder and collector’s dream. They come in such a wide variety of sizes and colors that there is sure to be a form for any gardener. Dahlia tubers are not terribly winter hardy and will rot in the ground in many regions. They split in freezing temperatures and mold in soggy soil. It is best to dig them up and store them indoors for the cold season and then reinstall them in spring.
Tips for Saving Dahlias
There are several ways of storing dahlia tubers for winter. The crucial part of the process is cleaning and drying. However, even the best methods still require you to inspect the tubers occasionally over the course of the winter. Environmental changes in the storage location, such as increased humidity or fluctuating temperatures, can still damage overwintering dahlia tubers.
Whether you have the dinner plate sized bombshells or the dainty lollipop variety, it is important to know how to remove and store dahlia tubers. The plants are perennials in USDA plant hardiness zones 6 to 7 but will succumb in the ground in lower zones. So, your choice in colder climates is to treat them like annuals or dig them up for storage. Dahlia storing only takes a few minutes and a couple of inexpensive materials.
How to Remove and Store Dahlia Tubers
Wait until the foliage has turned yellow before digging up the tubers. This is important so that the plant can gather energy for the following year. It will store starches in the tuber which will fuel initial sprouting in summer.
Cut off the foliage and carefully dig out the tubers. Brush off excess dirt and let the tubers dry for a few days. If possible, hang them upside down when drying them so that moisture can leach out of them.
Drying is important to saving dahlias over winter and preventing them from rotting. However, they do need to keep slightly moist on the interior to keep the embryo alive. Once the skin is wrinkled, the tubers should be dry enough. Once they are dry, they are packed away.
Storing Dahlia Tubers for Winter
Gardeners differ on the best way to pack overwintering dahlia tubers. Some swear by packing them in peat moss or sand in trays in an area about 40 to 45 degrees Fahrenheit (4-7 C.). You may also try storing them in a heavy plastic bag with packing material or even a Styrofoam ice chest. Separate the roots from each other with peat, cedar chips or perlite. In temperate zones where freezes are not sustained, you can store them in a basement or garage in a paper bag.
Some gardeners advise dusting the tubers with a fungicide before packing. Whatever method of dahlia storage you choose, you will need to check the tubers occasionally to ensure they are not rotting. Remove any that might be getting rot to prevent them from affecting all the tubers.
Plant them out again after all danger of frost has passed and enjoy their brilliant tones and flashy forms.
How To Dig and Store Dahlias For Winter
By Amanda S.
If you’ve ever grown Dahlias, you know they can quickly become a gardener’s prize flower. They steal the summer show with huge, colorful blooms, whether you grow dahlias to cut for endless bouquets, or to add a burst of color to the summer garden.
If you live anywhere but the warmest regions of the USA, you’ll need to learn about digging and storing dahlias at the end of the season! Native to Mexico, Dahlias do not survive freezing winter temperatures. Digging and storing dahlias for the winter is extremely easy and simple. When done properly, you can replant your Dahlias each spring, for year after year of fantastic flowers.
Follow our guide below to learn how to Dig Up and Store Dahlias For The Winter! We’ll cover when to dig, how to dig, and how to properly prepare and store your Dahlia tubers in a few smiple steps.
Dig your dahlia tubers up in the late fall before there is a hard frost in your area. See those enormous, woody stems that have been left behind? Those are from first-year tubers!
1. When To Dig Up Dahlias
If you live in an area where the ground freezes, you’ll want to dig your dahlia tubers up before there’s a hard frost. In our area (Northern Vermont) that’s usually late October, but it could be later depending on where you live. A good indication of when to dig your tubers up is when the plant starts to turn brown and die back.
If you live in an area where your ground does not freeze, such as parts of the far southeast and southwest, lucky you! Your dahlias can be grown as perennials and you don’t need to worry about digging and storing them for the winter.
Find your average first frost date with our helpful chart!
First Frost Dates
Cut foliage back to a couple of inches from the ground, before digging your tubers up.
2. How To Carefully Dig Up Dahlias Tubers
Digging tubers up is extremely easy:
- Cut foliage back, so that only a couple of inches remain above ground.
- Take your preferred digging shovel and dig around the tubers, being careful not to accidentally sever the roots. Many gardeners use a pitchfork to prevent this from happening.
- Once you’ve dug the tuber up, gently shake excess dirt off, and set aside.
- Repeat until you’ve dug all of your tubers up.
Gently shake excess dirt off of your tubers after digging them up.
8 Easy Steps to Lifting & Storing Dahlia Tubers
dahlia flower Nov 07, 2018
Everyone loves dahlias.
Who loves to dig them?
And I agree, it’s not as glamorous as harvesting lush blooms as the August dew rises.
But with a little planning and a bit of experience, you’ll save many times the tubers you planted, surrounding yourself with breathtaking abundance for the coming season. Plus a few extra for your best flower friends 🙂
Storing your own dahlia tubers is a labor of love but so, so worth it and not too challenging, with the right tips and tools.
Why Dig Dahlia Tubers?
There are many reasons and this is my favorite: You’ll have so many more dahlias for next season (not totally but essentially) for free.
Tuber productivity varies between varieties, but you’ll harvest 6 to 25 tubers for each tuber you plant. Not all will have full eyes allowing them to grow a stem next spring, but you’ll easily harvest more than you planted, and likely a lot more. Last week, dividing our dahlias, I had 18 perfect tubers to save from one single plant. If I get 6 from other varieties, I’m psyched. The variation is part of the fun.
Come spring, you’ll be glad you saved them — and so will your friends — if you’re sweet enough to share 🙂
1. Wait Two Weeks After Frost to Harvest Dahlia Tubers
It’s ideal to harvest and store dahlia tubers that have gone into dormancy, so they’re not shocked by the transition of summer growth to winter storage. Two weeks after your first frost is the ideal time to harvest them: they’re well into dormancy yet haven’t been harmed by the cold. It’s often cold and blustery, so do your best to choose a day that suits your sanity.
2. Trim Back Your Dahlia Stems
Just before digging your tubers, trim each stem back most of the way to the ground. We like to leave five to six inches of the main stem so we have a ‘handle’ to hold as we lift and rinse them. Dahlia stems, like straws, are hollow, making them quickly susceptible to rot. Which is all to say, don’t pre-emptively trim stems before you’re prepared to dig.
Dahlia stems are hollow and quickly rot when cut, so only cut just before you dig.
3. Dig Your Dahlias
If you have a choice (and often you don’t), dig your dahlias when it’s nice and warm (at least in a relative sense), when the soil is not totally wet. Since it’s deep into fall when we harvest here in Zone 5, the ground is often wetter than we’d like. But the soil isn’t likely to dry out until May, so we do the best we can.
A digging fork is infinitely more effective than a shovel, if you’ve got one. Either way, be sure to give your dahlias a wide berth. Each variety is unique: Some grow down, others grow out and some grow waaaaay out. Each tuber is attached to the central stem, or ‘neck.’ Especially as you begin to dig a new variety, dig in a wide radius so you break as few tubers and necks as possible.
Leave as much soil as you can in the garden, but resist shaking to protect the delicate necks.
Once lifted, loosen the soil that is easily left in your garden. Your goal is to break as few necks as possible, so resist the instinct to shake them. Use your fingers to ply soil away from the tubers. We often use the dahlia stems themselves to release more soil, especially when it’s cold and wet.
Gently tuck your dahlia tubers into a tote or wheelbarrow, as if you were handling eggs, bringing them to their next step in the process.
Before we go on, you have a choice to make: Divide now, in the spring or not at all.
Divide Dahlias in Fall
You’ll likely get more tubers that you would if you divided in spring, since the eyes are much more visible. They’re that much easier to cut, since they’re fresh, as well.
Divide Dahlias in Spring
You’ll likely get less tubers to re-plant, because the eyes will be so receded by winter’s dormancy. Also, cutting dahlias that have survived the winter is like cutting leather. I have friends who simply quarter them in spring and that satisfies them greatly.
If you don’t divide your dahlias in fall, lift each plant and remove all extraneous soil from the tubers in the garden. Put them, fully intact, in a fully closed plastic bag and store them in the coolest, darkest place in your home that won’t freeze.
Don’t Divide Your Dahlias
Always an option, and it’s simple enough. You won’t be able to propagate nearly as many new plants, but if you don’t need many this may be the easiest choice.
4. Rinse Your Dahlia Tubers
Pretend you’re washing fresh eggs, delicate and fragile. Protecting the necks of each tuber is paramount. That being said, your garden hose on ‘jet’ is quite ideal to rinse them. Resist shaking them and handle them as little as possible. Washing them right in the grass by your compost is great; we spray them on a mesh metal table adjacent our compost. Your goal is to clean your tubers as thoroughly as you possibly can, making the dividing that much easier. Some varieties clean more quickly than others; gentle patience is one of the key virtues of digging and storing dahlias.
Wash your dahlia tubers as you would eggs, protecting each fragile neck.
5. Divide Your Dahlias
Once your dahlias are thoroughly rinsed, bring them into a warm, well-lit workspace to divide them. Here are the tools I have on-hand:
– A table at the perfect height to cut
– Large cabbage or another harvest knife, sharp as can be
– Pair of sharp pruners, sharp as can be
– Dahlia knife, aka hawk’s or bull knife, sharp as can be
– Bowl of water large enough to spot-rinse your dahlias
– Bowl or tray for your tubers ready to store
– Compost bucket at the ready
Look at that tuber with the glorious cluster of eyes! A hooked dahlia or hawks knife is an essential tool for easy tuber division.
Dividing dahlias is a marvelous puzzle. Crosswords and sudoku are not fun for me, but boy, a wheelbarrow full of dahlias to divide brilliantly is just the kind of problem I love to solve.
Here is the key to dahlia division:
To become a glorious dahlia next season, your tuber must:
– be larger than a ping-pong ball
– with a strong neck that is not broken, even a little,
– with an ‘eye’ on the stem-end
Without such an eye, your tuber will grow only roots, but not a shoot to grow up, forming leaves and blossoms.
The tuber on the right is too narrow, it will most likely desiccate in storage. The middle tuber has no neck and no eye, so it won’t grow shoots next spring. The tuber on the left is absolutely perfect, with plenty of eyes at the end of a strong neck.
Start slow. Dahlia division is not to be rushed. Different varieties, with their unique tuber architecture and arrangement, are handled differently. Some varieties I mostly use my shears; others I rarely put down my dahlia knife. Learning the separate genius of each tool is part of the fun. Keeping your tools sharp and staying curious are the only imperatives.
6. Dust Your Dahlias with Sulfur
Once we divide all our tubers of a particular variety, we dip them into a bucket of powdered sulfur and vermiculite, providing an organic antifungal coat to prevent rot in storage. A spare dusting is quite ideal.
Dipping freshly divided dahlia tubers in vermiculite + powdered sulfur is a great organic approach to defying rot over the winter.
7. Pack them in Peat Moss
Tuck each tuber in a box with peat moss. It’s important that the box be fairly air-tight; we line our open-sided bins with plastic to ensure there is minimal moisture loss. Next, put down a one-inch layer of peat moss.
Here I’d like to add that I wish we could find a material other than peat moss for this step. Once we do, you’ll know! In the meantime, we use the same peat moss for many seasons, using it only for dahlia storage. Be sure it is very dry, though not bone dry.
On your one-inch layer of peat moss, lay your tubers so there at least an inch of space between each one. It’s important they don’t touch, so if one begins to rot it won’t spoil the rest. Keep adding peat moss, about an inch (enough to completely cover the last layer of tubers) until you’ve covered them all.
Many boxes will store your dahlias well. Just be sure to not have them be too moist or touching.
Label your box, inside and out.
Rather than covering the top of the box with un-breathable plastic, tuck newsprint so it maintains moisture but is still breathable.
8. The Perfect Place to Store Your Dahlias
Each home will have a unique place that is best suited for storing dahlias. Here are the key conditions to consider:
– as cold as possible without freezing, more consistent the better
– as dark as possible
– as dry as possible
Checking on Dahlias Throughout the Winter
Friends, it is essential to check in with your dahlias over the winter, making sure they’re neither too dry or too moist. Stay tuned for a blog later this winter sharing our secrets! We check in each month. At the very least, check them once.
Storing your dahlias each season is a labor of love, there is no doubt about it. If you love plants, love process and have a few good tips (you’re welcome!) along the way, you’re likely to love saving dahlias. Saving your own tubers is also one of the most cost-effective ways to surround yourself and those you love with beauty for years to come.
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How to overwinter dahlia tubers
There are two ways of overwintering dahlias, and which you choose depends on what role you want them to play in your garden.
In mild winters dahlias can be left in the ground, but to be avoid losing them you can easily lift them and bring them indoors.
Overwintering dahlias in single beds
If, like me, you grow dahlias for cutting in big beds, you can leave them in the ground over winter.
Mulch your dahlias in late autumn under several inches of mushroom compost or similar and just clear this away once the worst of the frosts are over in the spring. Overwintering dahlias like this means you do not need to lift the tubers.
Overwintering dahlias in a mixed bed
If you grow dahlias for late summer and autumn colour in a mixed border, you’re probably best lifting them. Pip Morrison (a great friend and garden designer who introduced me to Dahlia ‘Admiral Rawlings’), advises you are best to lift them as winter begins. Overwintering dahlias left in their beds will become overshadowed by spring and summer growth.
In an intensive and colourful bed, you also want to showcase earlier performers, such as a teepee of sweet peas or a big drift of a tall, impressive annual bedding plant like the invaluable Ammi majus. Dahlias can be slotted in to replace these, but in these circumstances, lifting it must be.
To be sure of conserving your plants for next year, dig them up after the tops have been frosted once or twice in the autumn. Cut them down to 15cm (6in) before you do so. Knock off the surplus soil and, with a small piece of stick, scoop out the loose soil between the tubers – but leave enough to hold them in place. Do not clean the tubers under a tap; to get water on a tuber at this time of year often spells disaster. Let them dry, hanging upside down from a dried stalk, leaving them there for a couple of weeks. Dust them with Bordeaux Mixture to discourage mould and mildew, then pack them away in a storage box in moist peat or sand. This prevents the tubers drying out. Store them in a cool, frost-free place – a cellar is perfect.
Overwinter your dahlias planted up in big pots – 3 litres or above – so they can grow to a decent size before planting out. Then whatever is flowering in the early summer can perform until the end of June, when the dahlias can go in to replace them, already impressive and almost in flower.
You’ll also need to stake and support all dahlias. Bar the ”container-sized” varieties such as Dahlia ‘Bishop of Oxford’ and Dahlia ‘Roxy’, all the ones I grow need canes and string to hold them up in wind and rain.
You may also like:
- How to plant and grow dahlia tubers
- The history of the dahlia
- Growing dahlias in pots (video)
Digging, Dividing, and Storing Tubers
Good, mature roots from healthy plants generally keep well, and any of several methods of storing tubers should yield 90 to 95 percent success. However, tubers from some dahlia varieties tend not to keep well, and some cultivars tend to give very sparse tubers. For these varieties, one should consider planting extras and growing pot roots.
Care of tubers starts with proper treatment during the growing season. While most dahlias start producing tubers in the spring, the roots do not mature until late in the growing season.
Before digging, go through the garden and throw away any weak stock. Dig up and throw into the trash any plants that were weak during the growing season or that produced inferior blooms. If any plants had signs of virus that could affect plant or bloom performance send them to the local landfill or incinerator. Before frost, be certain to have correct cultivar names attached to each stake, and be certain that the labels are easy to read (not badly faded).
The longer the tubers are in the ground curing, the more fully developed the tubers and the better the likelihood of their keeping over the winter. While one can start digging before frost or before the rainy season along the Pacific Coast (and may need to do so if his garden runs to thousands of plants), small growers should seriously consider letting their dahlia roots continue to grow and mature as long as practical. Most areas have a light frost that ruins partially opened blooms and top foliage followed by a hard freeze that may be a few weeks later. Dahlias continue to grow and the roots continue to mature after light frosts, and they may continue to grow after the first killing freeze (depending on how deep the freeze affects the soil.)
Cutting the Stalks
If one cuts a few days before digging, the eyes tend to come out, so the clumps are easier to divide accurately. However, if water gets into the stem, it can promote crown rot and ruin the tubers. Moreover, if one uses the same tool to cut all the stalks and leaves the plants in the ground, the tool could spread virus from one plant to another. To avoid spreading virus, dip cutting tools in a solution of one part bleach to ten parts of water before switching between one plant and the next. (See the ADS virus research reports for alternative solutions or sprays that kill virus on tools and on human hands.) Growers who cut the stalks a few days early should cover the open stalk with aluminum foil to minimize any water going down to the crown. (After the first frost, the stems always seem to have plenty of water in them, so some water there is unavoidable.) Leave enough stem (at least a few inches) to facilitate handling the clumps easily.
As soon as one cuts off the tops, an opportunity arises for the variety name to become separated from the clump. Carefully keep the tag with the proper clump at all times until finishing marking the individual tubers. Unmarked tubers (variety unknown) are worth a lot less than marked ones. In addition to the variety name, carefully indicate the best plants — propagate from the best, not the worst stock.
Dig and handle the clumps with care. A dahlia tuber’s neck is fragile, especially right after digging. To remove the clumps, dig on all four sides of the plant, about a foot away from the main stalk. When all four sides are loose from longer feeder roots, push the shovel or tined fork under the clump and lift carefully. Carefully remove any large clumps of dirt and turn the clump upside down to drain out any water in the stem. If one digs in the morning and leaves the clumps out for a couple of hours, the tubers will be much less fragile. After a couple of hours, one can remove the dirt with less opportunity of breaking fragile tubers.
When ready to clean the clump, use a garden hose to wash away as much dirt as possible. (Dirt contains microorganisms, so one wants to remove the dirt before storing the divisions.) At this time, the clump is ready for cutting.
Cutting clumps presents another tradeoff. It is much easier to divide roots in the fall (some varieties become so hard over the winter that one would need a power saw to separate them in the spring), but it is correspondingly harder to find the eyes before they start to sprout. Many growers divide their roots in the fall. Gardeners generally have more time in the fall than spring, and it is easier to remove dirt from and apply fungicide to divisions than to clumps. Growers uncertain about finding the eyes can cut off the tops several days before planning to dig so the eyes will have time to become more visible. Alternatively, just cut — some divisions will have eyes.
If a variety’s tubers are hard to keep or it makes tubers with especially thin necks and small crowns or especially small, thin tubers, then those lacking extensive experience may wish to divide the clump into sections and leave a few tubers together. One can keep the tubers from each division together with 3/4 inch masking tape.
Another suggestion for varieties whose roots are difficult to keep is to grow the plants in pots. Keep a rooted cutting or tuber in a 4 inch pot, plant the pot so the top is about an inch below the ground, and then treat the plant the same as any other dahlia in the garden. Because of the inch of soil above the pot, the feeder roots will come above the pot. However, the roots form and keep better if confined this way — even if one treats the plant like a show dahlia and not like a pot root.
Roots grown in pots are often smaller than roots grown in the open, especially since growers generally select varieties that are poor root makers to grow in pots. To harvest tubers in pots, cut off all but the top inch or two of stalk and dig up the pot. Cut away any hair-like roots that extend from the pots. One may shorten thick tubers that extend from the pot. One method to treat potroots is to remove them from the pot. (If the clump is pot bound, break the pot to get the clump out.) Wash, remove hair roots, let the clump dry for a day or two, and store in a bag with vermiculite. Alternatively, one may leave the potroots in the pots, place the name tag in the pot, and wrap the entire pot in half a dozen sheets of newspaper. Place the wrapped pots in brown grocery bags and store them with other tubers. In the spring, remove the pot and start watering. After a few weeks, one may take cuttings or (after the eyes develop shoots) unpot the roots, separate them, repot, and start the sections as individual plants.
Dividing the Clumps
In dividing clumps, each division must have a piece of the crown with an eye. Remove all of the stem, because any remaining tends to promote crown rot and ruin the tuber. ALWAYS STERILIZE CUTTING TOOLS AFTER DIVIDING EACH CLUMP. One finding from the ADS virus research project is that cutting tools will spread virus from one plant or clump to other tubers and ruin more of the stock. A solution of one part bleach to ten parts of water is the lowest cost effective treatment to kill dahlia virus on cutting tools and human hands. A few decades ago, experienced growers recommended sterilizing cutting tools with fire – heating the blades over a flame until red hot and letting the blades cool before reusing them. One can use hook-shaped carpet knives (inexpensive from a hardware store) and rotate several knives to economize on time spent waiting for individual knives to cool after sterilizing them.
While cutting the clumps, carefully inspect the divisions. Almost everyone throws away the “mother root.” Sprouts from the mother root tend to rely on it for nutrients and develop fewer feeder roots. With poor feeder roots, the result is poorquality plants and tubers. One prominent grower would save the mother root, use it for cuttings, and then throw it away.
Tubers need only be large enough to keep well through the winter without shriveling. Indeed, some experienced growers prefer small to large roots unless they plan to use the roots only to take cuttings (and then throw them away). Some varieties seem not to push to develop feeder roots if their tubers are large. For these varieties, smaller tubers (or large tubers with all but the top inch or two cut off and thrown away) will produce stronger plants and better blooms than larger tubers. However, smaller tubers are preferable only if they are fully mature. Immature roots from late, partially formed laterals seem more likely to rot than larger, more mature roots. A compromise is to rely on larger, more mature roots but to cut off all but the top few inches and throw away the excess. Keep enough of the tuber to mark its variety name clearly (see below). Overall, for best results, start a few tubers per clump in a 4 inch pot in the spring, let them all grow for a few weeks, and plant out (in the garden) the strongest plants.
Back to the clumps, remove all feeder roots and any stalk (both promote rot). If the inside of the crown has any brown or rusty colored areas, cut them away. The discoloration probably indicates crown rot, and the tuber is unlikely to keep. After cutting divisions, use a hose or indoor laundry tub (in cold weather) to wash the tubers again and remove any dirt missed when first washing the clump.
After rewashing, cut the end of the tuber. Any brown or rusty colored area in the middle or part of the way out indicates rot. If any of these signs are present, cut away toward the crown to see whether the tuber has a clear section that includes the crown. If so, the tuber should be viable. If not, throw it away.
Some tubers have insect holes part way down from the crown. Insect holes are only a problem if they make room for an organism that will promote rot. Cut above the insect holes and try to find a portion of the tuber without any brown or rusty area (as in the previous paragraph).
Treating for Fungus and Marking the Tubers
After cutting the divisions, treat the cut ends with a fungicide, such as Cleary’s 3336 (systemic and low in human toxicity), Captan, or sulphur. One may use the Captan or sulphur dry or follow directions to mix any of the chemicals in water and dip the roots. I have not heard any concern about spreading virus by using the dip for successive clumps. When using a liquid dip, place the tubers from one clump in the solution for about 15 minutes. Remove the tubers and transfer them to an empty shoe box or other open container (one per clump) to start drying. Never dry tubers on concrete, because it tends to draw the moisture from tubers and make them shrivel. Keep the tag with the cultivar name with the clump at all times. With a few containers, one can keep each clump in a separate dip and soak each clump approximately 15 minutes. Discard any tubers that float in a dip, because they will not keep. From more than 30 years of experience, I have not found any difference in how well tubers keep with or without a fungicide dip, so I no longer dip my tubers. What is most important is cutting away any signs of fungus in the crown or tuber before putting them away.
After cutting, mark each division with enough information to identify the variety name and (if there are multiples of each variety) which of the plants produced the tuber. An indelible pencil works well if the tuber is a little wet. Have a small container of water nearby to wet the pencil. One indelible pencil should mark tubers from more than 100 clumps. Since indelible pencils are toxic, never put the tip into the mouth.
The easiest method to mark tubers is to write the name of the variety. For long names, one can use a code — but DO NOT LOSE THE CODE! Some commercial growers write or stamp a number for each variety. In addition, indicate some way (such as with *) any especially good tuber (such as one to use to take cuttings next season).
After cutting, dipping, and marking the tubers, let them dry. Expect to let the tubers dry for about 24 hours for small roots and 24 to 36 hours for medium to large roots. Drying time varies depending on temperature and humidity. Do not dry the divisions on cement, because cement tends to draw out water and promote shriveling.
Anyone unsuccessful in working with an indelible pencil can still use a thin indelible marker to name the tubers once they have dried. The problem is that these markers do not always write well on tubers. Be certain to have several fresh markers and rotate them. Some nursery catalogs sell nursery markers, and office supply or drug stores sell less expensive (and sometimes less reliable) markers. Indelible pens work only on completely dry tubers. When a tuber is wet, the ink spreads and whatever one writes becomes unreadable.
Some growers attach labels with wires to mark each tuber. One grower cuts strips from empty plastic detergent containers, writes the cultivar name with an indelible marker, and attaches the strips to tubers with plastic wire.
Storing Tubers over Winter
There are numerous methods to store tubers over the winter. Various methods seem to work about equally well, as long as the procedure keeps the tubers cool (above freezing but ideally below 50 degrees) and allows an exchange of moisture between the tubers and the storage medium. The containers, however, must retain the moisture in the storage medium. If the moisture escapes, the tubers tend to shrivel.
Most growers seem to use vermiculite in plastic bags to store tubers that have dried for one to two days. Coarse vermiculite works better than the fine horticultural vermiculite. One opinion is that fine vermiculite tends to keep moisture too close to the tubers and make them sprout and develop too quickly. Also, vermiculite dust is hard on the lungs. The finer the vermiculite, the worse that problem.
A prominent grower in the Northwest would use slightly moistened sand in five gallon containers. The tubers kept very well but developed sprouts and feeder roots earlier than those in coarse vermiculite. Also, sand is much, much heavier. Perlite is not a good medium, because it does not absorb excess moisture, and its dust is unhealthy to breathe.
Experienced growers warn against peat moss. Dry peat moss tends to make tubers shrivel while moist peat moss tends to promote rot. Numerous growers use wood chips to store tubers, but some warn that wood chips leach moisture from roots. An inexpensive source of wood chips is pet bedding (available from pet supply outlets). Specify the higher quality wood chips that are supposed to be dust free.
Dipping tubers in paraffin wax was fairly popular in the Northwest several years ago. Tubers dipped in wax tend to be very slow to develop eyes. For cultivars that develop eyes very late, storing the tubers in wax would seem unwise. For varieties that develop sprouts and feeder roots in December, the wax method would seem more sensible. However, the wax treatment has not become popular despite several articles promoting it. The failure of this method to become popular probably indicates that the extra effort is not worth the trouble.
Numerous containers work well for storing tubers. While the discussion assumes coarse vermiculite, one can substitute wood chips without any additional changes. Add some vermiculite, put in some tubers, then add more vermiculite. Some growers use a separate bag for each clump. If a clump generates many divisions, one may need two bags. Each bag, however, must contain at least as much vermiculite (in volume) as tubers.
After filling the vegetable bags, stack them in doubled brown grocery bags and keep them in the coldest part of the basement or in another cool area that should stay around 40 to 45 degrees. An insulated garage with a space heater for the coldest part of winter works well for some growers. Some growers contend that the bags must be air tight while others only twist them so a little air can escape. Some growers in areas with very humid winters pierce holes in their plastic bags. In general, the smaller and thinner the roots, and the lower the average humidity during the winter, the more air tight one would want the bags.
One can also place the tubers in Styrofoam, wood, or cardboard containers with vermiculite separating layers. If one uses a wood or cardboard box, moisture could escape from the vermiculite. To retain the moisture, use newspaper at least eight sheets thick to line all sides of the container and keep the top of the container closed.
One should store the tubers at a nearly constant, cool temperature. Most growers seem to recommend a range of 40 to 45 degrees. Freezing temperatures ruin tubers, and higher temperatures encourage microorganisms and fungus to destroy them. Also, warm temperatures prompt tubers to develop sprouts and feeder roots too soon. One prominent grower uses a discarded refrigerator, not plugged in, with a plastic gallon container of ice changed every few weeks to provide cooling and humidity.
One should inspect tubers monthly during the winter. Throw away any tubers that show signs of rotting. By checking frequently, one can throw away rotting tubers before the rot spreads to otherwise healthy tubers. Some growers say that if one stores tubers so that they do not touch (as one could in a wood container but not in plastic bags), then rot will not spread. A rotting tuber releases a gas that hastens the developing of eyes and sprouts. A rotted tuber can therefore be useful for tubers that are very late to develop. Anyone who uses a rotted tuber for this purpose should check the bag frequently to ensure that the rot does not spread to the healthy, late tubers.
In early spring, move the tubers to a warm location (dark but room temperature) to encourage eyes to develop. One can add a teaspoon of water per quart of bag space a week to 10 days before removing the tubers. After adding the water, retie the bag and put it into a warm location.
Revised October 2019
I don’t know any gardeners who casually grow dahlias. Their fireworks riot of color has an intoxicating effect. You may start with one dahlia, but before you know it you have torn out the roses, planted five hundred tubers and (in at least one documented case), transformed an old tennis court into a fenced garden to make room for more flowers.
But dahlia devotees pay a price. In cold climates (read: the ground freezes), dahlia tubers need to come out of the garden if they are to survive the winter. Dig them up and store them in the basement, garage, or a protected shed—and dahlias will reward you next summer with more enormous puffball blooms. It’s worth the effort.
Here are step-by-step instructions for how to store dahlia tubers in winter:
Photography by Mimi Giboin for Gardenista.
Step 1: Wait for the First Frost
Above: Dahlias will bloom well into autumn if you deadhead them to coax more flowers. But frost will put a stop to that.
Flowers will wilt, leaves will blacken, and dahlia stems will die back after the first frost; you’ll know it’s time to store tubers in a safe spot for the winter.
Step 2: Dig Up Dahlias
Above: Be careful when you dig up dahlias because, as you can see, a single plant may have a clump of connected tubers and a far-reaching root system.
To dig up, first cut back stalks to a height of 2 to 3 inches. Then start about a foot away from the plant, loosening soil all around the roots and digging deep enough (18 to 24 inches) to get your shovel underneath the dahlia to tease it out of the ground.
Dig up one clump of tubers at a time and be gentle; the tubers are fragile and break apart easily.
Step 3: Rinse Off Dirt
Above: Use a gentle spray from a garden hose to wash off soil so you can see the tubers and root system of individual clumps of dahlias.
How to Overwinter Dahlias
Dahlias are heat loving plants that grow best with lots of sun and warm soil. Unlike most annuals and perennials, they are at their best in late summer and keep on blooming right through the fall. But as they say, all good things must come to an end. By October, dahlias finally start slowing down. And once there’s a hard frost, the season is definitely over.
At this point, you have two options. Treat your dahlias as annuals and just pull out the plants and plant a fresh batch of tubers next spring. Or, you can save the tubers from the varieties you really like and grow them again next year. Overwintering dahlias is easier than you might think. Read on for some easy, step-by-step instructions.
Though the dahlias in the photo above look dead, they’re not. A heavy frost has killed the flowers, stems and foliage. But the soil is still warm and is protecting the tubers from freezing.
If you live in hardiness zones 8-10, where winter temperatures rarely fall below 20°F, you can simply cut the plants back to the ground and leave the tubers right where they are. Your dahlias will start growing again in spring.
In hardiness zone 7, dahlias will usually survive the winter outdoors if the soil is well drained and you cover the area with a thick layer of mulch to insulate the tubers. To avoid any risk of freezing, it’s best to bring the tubers indoors. (Follow the instructions below for colder zones.)
If you garden in zones 3-6, you will need to dig up your dahlia tubers and store them indoors. For this task you need pruning shears, a shovel or digging fork, survey tape and marker, some damp growing mix, and either big nursery pots, black plastic trash bags or large boxes. Here’s how to do it:
How to Dig Up Your Dahlia Tubers
LABEL. Start by labeling your plants with survey tape (plastic plant labels are too easily lost). If your dahlias aren’t already labeled, be sure to do this BEFORE you get a frost so you can still see the flowers and evaluate which plants you want to keep. Save only the varieties that look strong and healthy and that really impressed you. There are tons of great dahlias out there and no reason to grow underwhelming ones.
CUT BACK. After the first hard frost, try to leave the tubers in the ground for a week or two. This helps toughen their skins (though it isn’t essential). Cut back all the stems to within 4” of the ground. Re-tie the labels as needed, so they are securely attached. If your dahlias are in containers, skip down to the section on packing and storage.
DIG. Dig up each root ball, starting at least a foot away from the stem. Depending on the size of the plant, the root ball may be 12” to 30” across and as much as 18” deep. Go slowly and be gentle, as the tubers are extremely brittle. Damaged tubers are more susceptible to decay.
DRY. If possible, let the clumps air dry for a day or two. Just make sure they are protected from frost. Tubers may be divided at this point, or you can wait and do it during the winter or next spring. If you plan to divide your tubers later, there’s no need to wash soil off the clumps. Just store the entire root ball as it came out of the ground. The soil gives them some natural protection from damage and rot. If you want to divide the tubers now (which will save on space if that’s an issue) see below for dividing instructions.
Packing and Storing Your Dahlias
PACK. The root balls may be stored in several ways. You can plant them into large nursery pots with damp potting soil. Or store them in ventilated cardboard boxes or plastic tubs that are partially filled with damp growing mix, peat moss or vermiculite. Another option is to store several clumps together in a large black plastic trash bag. Don’t seal the bag, just loosely gather the top so moisture stays in, but there’s still some air circulation.
STORE. Store the pots, boxes or bags in a cool, dark, humid place where the temperature will stay between 40 and 50 degrees F. An unheated basement is ideal. In zones 5 and 6 you may be able to keep them in an attached garage. Just make sure the tubers don’t freeze. A frozen tuber is a dead tuber.
CHECK. Check on your dahlias periodically through the winter. If storage conditions are too moist, you may get some mushy tubers. Remove them and increase ventilation to reduce the moisture level. If the tubers are wrinkled and dry, mist them or add some damp growing mix to help them rehydrate.
What to Do When Spring Arrives
In March or early April, go through all of your dahlias and discard any tubers that are soft or completely dried out. Then it’s time to start dividing the root balls into manageable-sized clumps. If you want to handle and replant an entire clump, go ahead. Otherwise, read on.
When dividing a clump of dahlia tubers, every division needs one or more growth eyes. These occur in a very specific location. In the photo below, it’s easy to see how the eyes are clustered on the knobby part where the tuber meets the stem. If you plant tubers that don’t have an eye, they will not grow.
It takes practice to see the eyes, and dividing clumps of tubers can be intimidating. If you wait until early spring, some of the eyes will start to swell and sprout. This makes it easier to see where to make the cuts. To be on the safe side, you can simply divide large root balls into halves or quarters. Cut down through the middle of the clump, making sure to leave some of last year’s stem attached to each division.
To learn more, watch our bulb expert Hans Langeveld in this video: How to Lift and Store Dahlias. For other info on dahlias, read: All About Dahlias, How to Pinch and Stake Dahlias, How to Plant Dahlias (video) and Dahlias: 8 Great Looks.
Storing dahlia bulbs for winter really isn’t very hard, and it’s well worth the effort. That way, you can grow your favorite dahlia flower bulbs year after year! In this post, I’ll show you how to dig up the tubers, and give you step-by-step instructions for overwintering dahlias.
I love dahlias. I mean who doesn’t, right?
Dahlias are a gorgeous addition to any summer garden, and they add such a cool tropical feel.
The best part is that you can easily overwinter dahlia bulbs in your house, and plant them in your garden again next year!
Oh Those Big, Beautiful Dahlia Blooms
I remember the first time I discovered dahlias. I saw a giant dinnerplate dahlia in a public garden… and it took my breath away.
I had no idea what it was, but I knew I had to have it!
So, when I got home I rushed to my computer immediately and started obsessing about it. After a few clever searches, I quickly found the ID of my newest favorite plant.
Of course I HAD to have one in my garden, and instantly became a girl on a mission. It wasn’t long until I had my prize.
Dahlias In The Garden
One sweet, beautiful, plump (plump?) dahlia bulb.
After giving it several kisses and doting on it (TMI? Maybe.), I grabbed my shovel and headed out to the garden. I wasted no time getting my new baby into the ground.
Several weeks later, I was rewarded with those gorgeous giant blooms I was dreaming about (I’m sure the kisses made all the difference).
But, with our short growing season, it wasn’t long before frost was in the forecast and panic set in.
Frost is always a major buzz kill!
Dahlia Rigletto Flowers
Do Dahlias Come Back Every Year?
Dahlias are tropical flowers, and they are not frost hardy. Dahlias can live for several years in warmer climates. But if you live in a cold climate like I do (Minnesota), dahlias won’t survive through the winter outside (boooo!).
So, I knew my new favorite flower wasn’t long for this world, but I didn’t want to lose it forever. So what did I do… (are you in suspense yet? Maybe a few more dots…)
… I dug up my dahlia flower bulb and stored it for winter. Of course!
Dahlias make a gorgeous addition to the garden or in summer pots, and they are a definite must in my garden every year (these days I grow several varieties).
But don’t worry, you can keep your favorite dahlias and regrow them every year in your garden, even if you live in a frozen tundra like I do!
Gorgeous Dahlia Flower
The good news is that you can dig up dahlia flower bulbs (BTW, technically they are tubers not bulbs, but I don’t see the Dahlia Police around, so we’re good) and store them in your house over the winter.
Then you can regrow them year after year. It’s a huge money saver. And guess what? It’s super easy to do too. Woohoo!
Preparing Your Dahlia Bulbs For Winter Storage
Before storing dahlia bulbs for winter, you must first dig them out of your garden (dah!).
But, if you grew your dahlia in a pot, you can skip this step and simply leave it in the pot all winter. Just cut back the foliage, bring the pot inside, and store it in a cool, dry place until spring.
If your dahlias are in your garden, follow these quick steps to get them ready for storage…
- Dig up your dahlia flower bulbs after frost has killed the foliage
- Gently shake off any excess dirt
- Cut off the stems and leaves
- Allow large bulbs to cure (dry out a bit) for a few days before storing. Smaller dahlia bulbs don’t need to cure.
No need to rinse all the dirt off your dahlia bulbs or split them apart. Just leave them in one large clump with a little bit of dirt and they’re ready for winter storage.
Overwintering Dahlia Bulbs
Storing Dahlia Bulbs For Winter
There are lots of ways of storing dahlia bulbs for winter.
Some people have great success just tossing their dahlia bulbs into a paper bag and storing them on a shelf in their basement.
But small bulbs can dry out using this method. So I prefer to take a safer dahlia storage approach.
- Cardboard box
- Dry to slightly moist packing material (I use peat moss, coco coir, wood chips (pet bedding is great) or sawdust. Whatever’s cheapest or I already have.) You could also use a mix of vermiculite and perlite if you have that on hand.
Steps For Packing Your Dahlia Flower Bulbs
- Line the bottom of the box with newspaper (optional, but it helps to keep the packing material from falling through the cracks) and a layer of packing material.
- Lay the dahlia bulb in the box so it will be surrounded by the packing material.
- You can store several dahlia flower bulb clumps in one box, but try to pack them so they’re not touching each other.
- Fill the box with packing material so that your dahlia bulbs are completely covered.
- Close the box and put it on a shelf (or whatever space you have). It’s important that your dahlia storage space is a cool, dry location that stays above freezing. If it’s too warm, your dahlia bulbs could rot.
Simple, right? Yes! I told you it was easy.
Storing Dahlia Bulbs Over Winter
You can try using different types of packing materials for storing dahlia bulbs for winter, or simply try wrapping larger bulbs in newspaper and packing them in boxes.
Experiment to find the dahlia storage method that works best for you.
Whatever you do though, don’t store dahlia flower bulbs in plastic bags or containers. If they are kept too wet they will likely rot or get moldy.
Most Posts About Overwintering Plants
- How To Store Bulbs For The Winter
- How To Overwinter Coleus Plants Indoors
- How To Overwinter Tuberous Begonia
- How To Overwinter Sweet Potato Vines
- How To Overwinter Caladium Bulbs
Share your tips for overwintering dahlias and storing dahlia tubers in the comments below.
Don’t dig up dahlias for winter! What to do instead….
November 12th, 2017 Posted In: Gardening know how
I don’t dig up dahlias to store them at the end of the summer.
I’ve been growing dahlias for fifteen years, and I only dug a few up once. They died.
But the dahlias I’ve left in the ground, year after year, have filled our late-summer borders with glorious colour.
All these dahlias were planted between eight and three years ago. I have never dug any of them up to over-winter.
Although, perhaps the borders are not exactly the colours I originally planted. But more of that later.
As soon as people see the late-summer border, they ask two questions. The first is always ‘do you dig dahlias up for winter?’
Our dahlia border
Of course, those who have ‘proper gardens’ almost always dig up their dahlias. Then they store them expertly, and they have places to do so.
But we’re a bit short of storage here, and my over-wintering expertise isn’t up to much either.
So this post is about middle-sized garden tactics, not ‘proper gardening.’
How not to dig up dahlias
Firstly cut away the dead and dying foliage. I find some of my dahlia stems are so thick, they need loppers not just secateurs. (I particularly like Wilkinsons Ultralight Loppers, because they really are so light.)
Note: links to Amazon in this post are affiliate links, which means I may get a fee if you buy through them, but it won’t affect the price you pay. I’ve only linked to products I’ve tried myself and liked.
Once you’ve taken away all the vegetation, cover the dahlia with as big a mound of compost or mulch as you can. Pile it on, making sure that the stems are well covered to protect the snow and rain getting in down the hollow parts.
Then add a stick to show you’ve got a dahlia there. It’s as simple as that.
But take your anti-slug precautions early
The second question people ask is how I keep the slugs and snails off the dahlias. As you can see, I co-exist with slugs and snails. But I prevent them from winning by starting the battle early.
You may not feel inclined to take my anti-snail advice, having seen this picture. But at least I enjoy my dahlias as much as the snails do.
Best tip: I got this from a friend in the RHS. Start taking your anti-slug and snail precautions in February. Don’t wait until you see snail damage. I use ferric phosphate slug pellets, which are certified for organic use,and are pet and wildlife friendly.
I’ve used several brands, such Bayer Garden Slug Killer and Sluggo
Take a handful and simply throw them across the border in February. Don’t try to make little piles around where you think the plant will be. A light sprinkling will help protect your dahlias.
Some dahlias do really need to be dug up…
I must admit one thing.
Not all dahlias survive the winter protected by mulch, so I have lost a few over the years. The colour scheme is now dominated by reds and oranges, although the beautiful peach ‘Henriette’ has come back three years in a row.
This is Henriette. She is so pretty, and has come back every year for three years now, protected by a big pile of mulch.
Dark red Rip City and Black Cat dahlias have proved hardy, and also the orange Dahlia David Howard. However, a few dahlias haven’t survived, no matter how much mulch I pile on top.
The dahlias that do come back seem extra vigorous, perhaps because of their nutritious mulch meal. This is ‘Con Amore’.
So it’s a question of trial and error. And it also depends on where you live, – we’re in Southern England, so we have some quite mild winters and some harsh ones. It’s usually considered equivalent to a US hardiness zone 8, although it doesn’t quite match.
The secrets of growing dahlias…from an expert!
Steven Edney, the award-winning head gardener of The Salutation Hotel & Gardens, comes from a family of professional dahlia growers. For his advice on how to choose dahlias, how to plant dahlias and what to do about slugs and snails, see this video, which also features the beautiful gardens at The Salutation.
What you say….
Update: since this post appeared, I’ve had many comments (see below) and on Twitter. Some people find that dahlias survive the cold under mulch, but struggle in wet or poorly drained soil.
Gardening writer Susie White, who gardens in Northumberland says that she leaves her dahlias in the ground successfully, in spite of being in a frost pocket. Her garden was featured on Gardeners World as an example of gardening in extreme temperatures! However, she does have well drained soil, and adds a deep mulch. She has even managed to keep the black-leaved ‘Bishops children’ alive!
Blogger The Reckless Gardener also leave his dahlias in the ground, although his Cumbria garden is also in a frost pocket. ‘Glad to see another gardener being reckless, too….’
If you love dahlias and would like to know more about them, Naomi Slade has written a glorious book about them called Dahlias – Beautiful Varieties for Home and Garden, with photography by Georgianna Lane.
See it on YouTube
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(Although Anne Wareham is pretty good at not doing gardening in her book The Deckchair Gardener)
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