Originally Published by Sandra Mason on 7/22/2000
The Greek goddess Iris walked a rainbow pathway through the sky and the flower named for her has a rainbow of flower colors. Iris is one of the oldest garden flowers. Iris is often seen as the only remnant of a long since abandoned home.
Although the most familiar type of iris is the bearded iris, the genus includes 200 or more species including some North American natives. Species are separated into two major groups – rhizomatous and bulbous. Rhizomes are horizontally growing underground stems that are used as food storage for the plant. The common bearded iris falls into this group as well as the beardless Siberian and Japanese iris.
Bulbous irises form a more typical bulb and include Dutch and reticulate iris. These are planted in October with other bulbs.
The best time to plant and transplant rhizomatous iris is late July through September. Iris loves the heat and drier weather of summer and the summer dividing will reduce the incidence of bacterial soft rot. Most rhizomatous iris should be divided every three to five years. If your iris patch is producing very few flowers, it’s time to divide and conquer.
When transplanting iris, first cut back the leaves to about one third of their height. Lift the entire clump with a spade or digging fork. Use a sharp knife to separate the rhizomes. Dip the knife in ten percent bleach after each cut. The new transplants should have a firm rhizome with roots and a fan of leaves. Remove and discard the old rhizomes and only replant the younger smaller rhizomes that grow off of the older stems.
Iris appreciates a sunny well-drained garden spot. When planting iris, dig a hole about five inches deep. Build a small mound in the middle of the hole. Place the rhizome firmly on top of the mound and let the roots fall down the mound. Cover the roots with soil so the rhizome is just slightly exposed. Do not plant the rhizome too deep or it may rot. Generally iris are planted 18-24 inches apart in groups of three to seven sections of one variety. Usually the rhizomes are planted so the leaf fans face in one direction.
While dividing the rhizomes be sure to inspect them for soft rot and iris borer. Iris borer is the worst insect problem irises ever get. The adult iris borer is a brownish moth. She lays her eggs in fall on the iris leaves. The eggs overwinter and hatch into caterpillars during April and May. The caterpillars first bore into the iris leaves. By the end of July the caterpillars move into the rhizomes to eat and mature. In early August the caterpillars move from the rhizome to the soil to pupate into a moth.
When dividing iris, the iris borer will be a mature pink caterpillar inside the rhizome. The rhizome may look fine until your fingers push through to a mushy mess. Bacterial soft rot often accompanies iris borer damage.
Fall sanitation is important in iris borer control. After the first hard frost, remove and destroy or bury the old iris leaves and plant debris to remove the eggs. In small iris patches the borer can also be controlled by squishing the caterpillar in the leaves in April and May.
With so many colors and types of iris available including rebloomers, include a few in your garden plan.
If you find you just have way too much produce, why not donate it to “Plant a Row for the Hungry.” Drop off your extra produce at Schnuck’s Grocery Stores in Champaign or Urbana each Saturday from 10am–1pm starting July 22. All produce goes to the Eastern Illinois Foodbank.
1. Q. I love to grow iris but my entire planting bed does not bloom as it once did. Should I replant? My neighbor has beautiful iris that I could replant with. When should iris be transplanted?
A. Iris beds need “thinning” periodically (every two or three years). September is the ideal time to plant or to divide and replant iris – the common man’s orchid. Here’s how it’s done.
Before digging rhizomes (roots), cut leaves back to about one-third their full height. Dig under a clump of rhizomes, and lift out the whole clump at once. When dividing and replanting, use only the strong, healthy rhizomes for planting.
Cut rhizomes into sections, containing one to three buds. Each division must have at least one growing point (or fan of leaves), a few inches of healthy rhizome, and a number of well- developed roots.
Discard diseased and stunted plants. Disinfect pruning shears if you accidentally cut into a diseased rhizome using a solution of one part household bleach to nine parts water.
Plant iris in a sunny, well-drained area with good circulation around the plants to prevent diseases. If the soil is poorly drained, consider using raised beds, since iris will rot in poorly drained soils.
After planting, water the bed thoroughly to settle the soil around the roots. Usually no additional moisture is required unless a prolonged water drought occurs.
2. Q. When is the best time to transplant and/or separate iris? How should I prepare the planting site?
A. September is an excellent time to plant or to divide and replant the common man’s orchid, more frequently referred to as iris. The new beds should be prepared at least a week prior to planting to allow the soil to settle.
Select a loamy soil in a sunny, well-drained area of the yard. If soil is poorly drained, consider using raised beds as iris will not tolerate wet, poorly-drained soil as the rhizomes tend to rot. Incorporate a complete fertilizer into the upper 6 to 10 inches of soil using one pound per 100 square feet of bed area. Also apply superphosphate at the rate of one-half pound per 100 square feet of area.
When dividing and replanting use only the strong, healthy rhizomes for planting. Cut rhizomes into sections containing one to three buds each. Discard diseased and stunted plants. To plant the prepared rhizomes, form a mound of soil in the bottom of the planting hole so that the top of the mound is about one inch below the surface of the bed. Place the rhizome on top of the mound with the roots spreading outward. Press the rhizome into the soil mound until it is at or below the soil level then finish filling the hold so the roots are covered and the rhizome is just barely covered.
There is a mistaken idea that iris foliage should be pruned back each year. Actually there are only two reasons to justify this practice. The first is to prepare the plants for digging and transplanting and secondly to remove diseased foliage especially at transplanting time. When trimming the foliage, cut it back to one-third its original height. In established beds, do not cut the foliage as it is needed to build up food reserves for flowering the next spring.
After planting, water the bed thoroughly to settle the soil around the roots. Usually no additional moisture is required unless a prolonged water drought occurs. Iris usually suffer more from too much water rather than a lack of moisture; however, they can be damaged if the roots and rhizome are allowed to become completely dry.
- Dividing and Moving Iris – How To Transplant Iris
- Signs You Need to Transplant Iris
- When to Transplant Iris
- Steps for Dividing Iris Plants
- Steps for Transplanting Iris
- Yard and Garden: Dividing Irises
- When and how do I divide irises?
- September is a good time
- Thorny problems: when should I move an iris?
- How to Grow Bearded Iris for a Garden Full of Color
- Iris Growing Tips
- How to Divide Bearded Iris
- Great Bearded Iris Varieties
- Bearded Iris Care: How To Avoid 5 Common Growing Problems
- Problem #4: Pests & Diseases
Dividing and Moving Iris – How To Transplant Iris
Transplanting iris is a normal part of iris care. When well cared for, iris plants will need ro be divided on a regular basis. Many gardeners wonder when is the best time to transplant iris and how should one go about moving iris from one place to another. Keep reading to learn more about how to transplant iris.
Signs You Need to Transplant Iris
There are a few signs that you should consider dividing iris plants.
The first sign that your iris need divided will be decreased blooming. Overcrowded iris rhizomes will produce fewer flowers than uncrowded iris rhizomes. If you have noticed that your iris are blooming less than they have, you may need to transplant the iris in your garden.
The next sign that you should consider transplanting your iris is if the rhizomes start heaving out of the ground. Overcrowded iris rhizomes will start to push on each other, which results in the entire root system of your iris plants literally pushing themselves out of the ground. The iris roots may look like a mass of snakes or a pile of spaghetti when they need to be divided. They may
even stop putting up foliage and the plants may only grow foliage on the outside edges of the clump.
When to Transplant Iris
The best time when to transplant iris is in the summer, after the iris have finished blooming, up until fall.
Steps for Dividing Iris Plants
To divide your iris, start by lifting the clump of iris plants out of the ground with a spade or fork. If possible, lift the whole mass out whole, but if you are unable to do this, carefully break the clump into smaller parts and lift these out.
Next, brush of as much dirt as possible from the iris rhizomes. This will make it easier to see when you are breaking the clumps apart.
The next step in dividing iris plants is to divide the iris rhizomes. Each iris rhizome should be divided into pieces that are 3 to 4 inches long and have at least one fan of leaves on the rhizome. Do not remove the roots from the rhizomes.
As you get closer to the center of the clump, you may find large sections of rhizomes that have no leaf fans. These can be discarded.
Check all of the divided iris rhizomes for iris borers and disease. The iris rhizomes should be firm and not soft. If the rhizome feels soft, throw it away.
Steps for Transplanting Iris
Once the iris rhizomes have been divided, you can replant them. First, trim all of the iris leaf fans back to about 6 to 9 inches tall. This will allow the plant to re-establish its roots without having to support a large amount of foliage at the same time.
Next, plant the iris rhizomes in the selected location. This location should receive a good deal of sunlight and should be well draining. Dig a hole where the rhizome will settle into the ground just below the ground level. If planting several iris near each other, point the rhizomes away from each other and space them 18 inches apart.
Spread the roots out around the rhizome and then cover the roots and the rhizome with dirt. Water the newly transplanted iris plants well.
Yard and Garden: Dividing Irises
AMES, Iowa – Recommendations for when to divide irises depend on the species. Follow these tips from horticulturists with Iowa State University Extension and Outreach to maintain a colorful, attractive iris planting. To have additional questions answered, contact Hortline at [email protected] or call 515-294-3108.
When should bearded irises be divided?
Bearded irises should be divided every three to five years, as the plants quickly become overcrowded and don’t bloom well. July or August is the best time to dig, divide and transplant bearded irises.
How do you divide bearded irises?
Bearded irises grow from thick, underground stems called rhizomes. In July or August, carefully dig up the iris clumps with a spade. Cut back the leaves to one-third their original height. Wash the soil from the rhizomes and roots with a steady stream of water. Then cut the rhizomes apart with a sharp knife. Each division should have a fan of leaves, a healthy rhizome and several large roots. Discard all diseased or insect damaged rhizomes.
Bearded irises perform best in fertile, well-drained soils and full sun. In clay soils, incorporate compost or sphagnum peat moss into the soil prior to planting. When planting bearded irises, dig a hole large enough to accommodate the rhizome and roots. Build a mound in the center of the hole. Place a rhizome on top of the mound and spread the roots in the surrounding trench. Then cover with soil. When planted, the rhizome should be just below the soil surface. Finally, water each plant thoroughly.
To obtain a good flower display, plant at least three rhizomes of one cultivar in a group. Space the rhizomes 12 to 24 inches apart.
When should Siberian irises be divided?
Siberian irises don’t have to be divided as often as bearded irises. It’s advisable to divide Siberian irises when clumps become crowded, plant vigor declines or clumps have formed solid rings with bare centers. Siberian irises can be divided in early spring or late summer.
How do you divide Siberian irises?
When dividing Siberian irises in early spring, dig up the entire clump when new growth has just begun to appear. Divide the clump into sections with a soil knife or spade. Each section should have several growing points and a good root system. Replant immediately. Siberian irises perform best in moist, well-drained soils in full sun. When dividing plants in late summer (August), dig up the entire clump, cut back the foliage to 6 to 8 inches and divide the clump into sections with each division containing several fans of leaves and a good root system. Promptly replant the divisions.
Photo credit: Anka100/iStock/Thinkstock
When and how do I divide irises?
September is a good time
Here’s the thing about writing a gardening column: There is so much great information to share and so little space to share it fully.
For that reason, I’m prone to offering lots of tips and suggestions, but not so much in the way of detailed guidance. It’s just hard to fit it all in! I always hope that readers who want to know more will seek out a knowledgeable source for assistance—Extension System experts, Master Gardeners, garden-wise friends and relatives, books, magazines and, yes, the Web. And, honestly, even if I had all the column inches in the world, I’d still encourage readers to track down experts who have loads more experience and knowledge than I will ever possess.
Still, my ever-creative and reader-oriented editors at Alabama Living offered an idea on how to better address the questions my tips and ideas may evoke. So here’s a stab at it, starting with a question my sister recently asked after reading a tip in my July column: So how do I divide irises?
Though the ideal time to divide irises it just after they bloom, in most parts of Alabama it’s fine to divide and replant them (and many other perennials) throughout the month of September, so it seemed an appropriate question to tackle this month.
Over time, the rhizomes (main roots) of irises produce lots of “baby” rhizomes that need to be removed and relocated so parents and children alike can thrive, thus the need to divide irises. To divide them, carefully lift the plant clump and its rhizomes/roots out of the ground with a garden shovel or fork, then gently separate individual rhizomes from the clump by snapping or cutting them apart. If you have more than one kind of iris in your yard, you may want to group them according to their color and/or cultivar as you do this.
Wash any excess soil off the rhizomes, soak them for 10 minutes in a 10:1 water:chlorine solution, then rinse them with fresh water and allow them to air dry in the shade for at least 30 minutes. From this freshly cleaned and dried collection, select the healthiest rhizomes for replanting or sharing and discard any that look diseased, shriveled or just plain puny. Try to replant them as soon as possible, preferably the same day.
As you replant the rhizomes, don’t bury them too deeply. Iris rhizomes need to be close to the soil’s surface and either partially exposed or only lightly covered with soil to reach their full blooming potential next year.
Another question my column recently elicited was about cover crops. Cover crops, unlike perennial ground covers used in the landscape, are annual crops that are used to hold and build soil between planting seasons in vegetable gardens.
As the summer gardening season comes to an end, you can replant the area with cool-season vegetables (cabbage, collards, lettuces, garlic and onions, for example).
But if you’re planning to leave the space dormant this winter, consider planting it with crimson clover, rye, soybeans, hairy vetch, oats and other legume or cereal crops. These crops help hold the soil in place, build soil quality and, depending on the cover crop you choose, can add nitrogen to the soil, suppress weeds, help control some insect and disease pests and attract pollinators.
Cover crops will protect and enhance your soil all winter and, next year, can be used as “green manure” by mowing the cover crop in late winter or early spring, letting it dry for a week or two, then working the crop residue into the soil as you prepare the garden for the coming vegetable season.
More information on what kinds of cover crops to use and how to use them in vegetable gardens can be found through your local Alabama Cooperative Extension System office or in the Extension publications Cover Crops for Alabama (available here) or The Alabama Vegetable Gardener (available here).
And if you have gardening questions, send them on. If I don’t know the answer I will try to find someone who does, and your question may well be fodder for a future column!
Katie Jackson is a freelance writer and editor based in Opelika, Alabama. Contact her at [email protected]
September Gardening Tips
- Make notes about what did and didn’t work in this year’s garden for use as you plan next year’s garden.
- Clean dead plants and debris from garden beds and the landscape.
- Add lawn and garden debris to the compost, along with any organic (non-meat) kitchen waste.
- Test your soil so you’ll know what amendments to add this fall and winter.
- Plant fall and winter vegetables and root crops, such as cabbage, collards, celery, garlic and onions.
- Continue to mow and irrigate lawn as needed.
- Fertilize azaleas and camellias.
- Plant winter grass seeds on bare areas.
- Plant perennials and biennials and spring-flowering bulbs.
- Divide perennials and thin or transplant irises and daylilies.
- Clean bird feeders and birdbaths and keep them filled throughout the fall for resident and migratory birds.
Thorny problems: when should I move an iris?
My wife has a pair of bay trees in pots in the conservatory. One of them is secreting a sticky substance that is very hard to clean off any surface it touches. Is there a cure for this, or does she have to destroy the tree?
John Ford, via email
The culprits here, the oozers of the hard-to-clean sticky stuff, are undoubtedly some sort of scale insects that have colonised the leaves of the bay, and are thriving in the cushy environment of the conservatory. The insects may well be hardly visible, clustered like miniature limpets around the ribs of the undersides of the leaves.
Alas, a product that used to be extremely useful for keeping on top of conservatory and house plant pests, Bug Clear Ultra for Pots, is no longer with us. It took the form of little “match sticks” that you pushed into the soil. When damp they exuded a (presumably now banned), neonicotinoid insecticide that was absorbed by plants via their roots, causing leaf pests to drop off their perches.
In the absence of this product, you will have to take the bay trees outside on a mild day and spray them all over (leaf undersides as well as uppersides), with a contact/systemic spray such as Provado Ultimate Bug Killer Ready to Use. Harvest a year’s worth of bay leaves for the kitchen before you spray, of course.
As your wife is probably aware, these bay trees will be much happier outside from March/April to October/November. I hesitate to say they are totally hardy outside all the year (I don’t know your geographical location or garden circumstances), having fielded so many “Help! Are they dead?” questions about bay trees after the last two hard winters. But I should say that if these trees are to be overwintered indoors every year, they may always have a pest problem in late winter. A preventive spray in the autumn and again in the New Year should maintain control.
Our old bramley apple tree, pruned every year, has served us well. However, 2012 (a poor year generally), brought 18 apples and last year, when the rest of Kent had a good harvest, the tree produced nine fruits. Has the tree reached the end of its working life or is there anything we can do to restore our apple supply?
Jenny Phillips, via email
Bramleys can go on for years and years, knotted and gnarled, but still be productive, so I doubt your tree is on its last legs. There are two possibilities, I think, the first being less likely than the second: the first is about pruning – only likely if someone new has been pruning your tree and “went too far”, cutting the tree drastically so that it has made leafy shoots and not much else. Alternatively, your tree produces blossom that doesn’t set – in which case you have a pollination problem.
Bramleys need to have other apple trees in the vicinity that flower at the same time in order to set fruit. The recent lack of apples could simply be down to the fact that you were unaware that a local orchard has been grubbed out, or that apple trees in neighbouring gardens have been cut down. Bramley trees cannot pollinate themselves. So a simple solution, if you have the space, might be to plant two more apple trees that flower at the same time. ‘Cox’s Orange Pippin’ and ‘Katy’ might be a good combination.
Back to box
I have very old large box plants in 12in pots. They have been kept alive by MiracleGro in the summer but now hardly put on any growth. I am considering planting them in the garden. Is this advisable? If so, any advice as to their maintenance would be appreciated.
Jennifer Salt, via email
I expect it has become quite hard to water these old plants, so compacted have their roots become, and they will probably continue to go downhill unless you take action. If you have some suitable space, then by all means get them into the ground. The following advice holds good for planting any pot-bound shrubs into the ground:
Prepare a planting hole for each as you would normally do, mixing a couple of fistfuls of bonemeal and plenty of garden compost or equivalent into the removed soil. Make sure that the congested roots of the box plants are released from the rigid shape that the pot created over the years, and that they are thoroughly moistened. To achieve this, when you de-pot them, gently bash (I am aware of the contradiction this description presents), some of the dry, impoverished soil off each root ball and snip cleanly away any roots that look damaged or dead. Put each shrub in the prepared planting hole and water them well twice before you backfill and firm the ground around them gently with your boot.
Water once more, then apply an organic mulch over the surface of the soil. In their first summer after the transferral from pot to ground, you may need to water them once or twice. Thereafter, annually fed with a balanced fertiliser, they should thrive.
Buy plants, tools and accessories from the Telegraph Gardenshop.
How to Grow Bearded Iris for a Garden Full of Color
It’s a magical time when bearded iris flowers unfurl their pencil-slim buds to reveal a kaleidoscope of color, beginning as early as March in warmer regions. Depending on the type of bearded iris, they can be in bloom all the way into June. Some types even rebloom in late summer and fall. These hardy perennials flourish in USDA Zones 3-9, where winter temperatures dip below freezing and allow the plant to go dormant before next year’s growth.
“Anyone can grow iris,” says Doris Winton, who has had a lifelong attraction to this plant and is a master judge for the American Iris Society. It’s easy to understand why people have such passion for iris—it’s a very diverse group of plants, with bearded iris being one of three main categories. This kind of iris is so named because of a patch of soft bristles on the lower petals of the flowers. In addition to their long bloom time, bearded iris come in an incredible variety of colors and patterns. “Every color—except fire-engine red—can be found in bearded iris,” Doris says.
No matter which varieties you choose to grow, there are a few things you can do to help them thrive in your garden.
Iris Growing Tips
- Plant them in a sunny spot in late summer. The plants need well-drained soil and at least six hours of sunlight per day. A full day of sun is even better to keep the rhizomes dry. (The rhizomes are the fleshy rootlike structures at the base of the plant.)
- Prepare their beds. Use a low-nitrogen fertilizer and apply it twice a year—in early spring and just after bloom when the rhizomes are forming the next year’s flowers. Water only if it is extremely dry or after transplanting.
- Give them room to breathe. Bearded iris require good air circulation. Plant them a minimum of 16 to 18 inches apart (less space for dwarf irises and more for tall bearded iris varieties).
- Do not mulch. Mulching retains moisture, and too much moisture will cause the rhizomes to rot.
- Remove seedpods that form after the blooms have faded. This prevents seedlings from choking the surrounding soil. Seed formation also saps energy needed by the rhizomes, roots, and leaves.
- Prune back the foliage in the fall. This will reduce the chances of overwintering pests and diseases.
- Make dividing a habit. Divide clumps of bearded iris plants every three to four years in late summer.
Buy It: Tall Bearded Iris, from $14, White Flower Farm
How to Divide Bearded Iris
Bearded iris grow from a thick, rootlike structure called a rhizome. As the plant matures, the rhizome produces more rhizomes, which in turn lead to more leaves and flowers. Over time, however, the original rhizome withers and dies off. When this happens, bloom production slows and it is necessary to divide the plant, removing and replanting the newer rhizomes so they have the space they need to fully develop.
Bearded iris should be divided in the late summer when the weather starts to cool. The division process illustrated below can be used for other plants that produce rhizomes, including canna, bergenia, dahlia, toad lily, and lily-of-the-valley.
Step 1: Dig Up Clumps
Carefully dig the clumps with a garden fork or spade, taking care not to chop into the rhizomes more than necessary.
Step 2: Break Apart Rhizomes
Divide the rhizomes by pulling them apart with your hands. In some cases, you may need to use a sharp knife to separate the smaller rhizomes from the main one. If so, dip your knife into a 10-percent bleach/water solution between cuts so you don’t spread any diseases to new rhizomes.
A good rhizome will be about as thick as your thumb, have healthy roots, and have one or two leaf fans. Large, old rhizomes that have no leaf fans can be tossed out.
Image zoom Image zoom
Step 3: Rinse and Evaluate Rhizomes
Wash the soil off the rhizomes to that you can inspect each one for iris borer (a plump, white worm). If you find a borer, destroy it. Some gardeners like to wash their iris rhizomes in a 10-percent bleach solution to protect against disease, but that won’t help plants that are already rotting. Make sure to discard any soft, smelly rhizomes you find, as well as any that feel lightweight or hollow, or appear dead, like the rhizome shown above.
Step 4: Cut Leaves
Clip off the leaf blades so that they’re 4 to 6 inches long. This reduces the stress that the plant goes through as it concentrates on regrowing new roots instead of trying to maintain long leaves.
Step 5: Plant Divisions
Replant divisions, setting the rhizome higher in the planting hole than the fine roots, which should be fanned out. A bit of the top surface of the rhizome should be just visible at the soil surface.
Step 6: Plant Remaining Rhizomes and Water
Space the plants 12 to 18 inches apart (closer for dwarf varieties, farther apart for the largest). For the best display, plant the rhizomes so the fan of leaves face the same direction. Water well when planting bearded iris rhizomes, but do not continue to water unless the weather becomes dry.
Image zoom ‘Fringe of Gold’ bearded iris
Great Bearded Iris Varieties
Iris flowers have three primary structures, and descriptions of a variety often refer to these parts. For example, in the ‘Fringe of Gold’ flower shown above, the drooping “falls” are white-edged (or picoteed) in yellow. The upright “standards” are solid yellow. And the tiny fuzzy “beard” in the middle is white and yellow. You can use these structure names to imagine how an iris might look when you have only a text description.
As a longtime lover of bearded iris, Doris Winton has many favorite varieties, including ‘Fringe of Gold’. See below for several more of her favorites.
Image zoom This variety is a dwarf tall bearded iris with yellow blooms. The petals have a white and deep purple veined pattern that makes for a bold contrast on each bloom. Plant these irises in full sun. Zones 3-8
‘Bumblebee Deelite’ Dwarf Bearded Iris
This variety is a dwarf tall bearded iris with yellow blooms. The petals have a white and deep purple-veined pattern that makes for a bold contrast on each bloom. Plant these irises in full sun. Zones 3-8
‘Rebecca Perret’ Bearded Iris
White petals fade into light purple on the tips on this softer bearded iris variety. The mid-height selection can thrive in full to part sun. Zones 3-8
‘Perfect Pitch’ Bearded Iris
‘Perfect Pitch’ is a true purple bearded iris that has ruffled petals. This cultivar does best in full sun and is considered a tall variety. Zones 3-8
‘Ozark Dream’ Dwarf Bearded Iris
If you love purple, ‘Ozark Dream’ is the bearded iris for you. The top petals of the bloom are a light purple, while the falls are dark violet. Plant this cultivar in full sun. Zones 3-8
‘Latin Hideaway’ Bearded Iris
This tall bearded iris variety has a large contrast between the top petals (which are white) and the falls (in a brick red hue). The red falls petals have a hint of magenta near the center, and the inside of the white petals has a light pink hue. Zones 3-8
‘Gallant Moment’ Bearded Iris
The scarlet blooms of this bearded iris variety make it stand out in the garden. The petals fade into orange and gold tones toward the center of the bloom. The outer edges of the petals become such a dark red that they almost look chocolate brown in places. Zones 3-8
- By BH&G Garden Editors
Bearded Iris Care: How To Avoid 5 Common Growing Problems
Problem #4: Pests & Diseases
Pests and diseases in Bearded Iris often vary by geographic location and gardening conditions. One general rule of disease prevention is to keep your garden clean from debris and weeds as much as possible. Having said that, pests and diseases can show up in even the most pristine gardens, so it is good to learn how to diagnose and treat these issues.
Bacterial Leaf Spot (Disease)
How To Identify: Bacterial Leaf Spot (or Bacterial Leaf Blight) shows up on the edges of the leaf tips as small, pale spots. They then grow larger and develop white centers. This disease usually shows up when there has been a particularly mild winter.
How to Prevent: Bacterial Leaf Spot can be tough to prevent. Keep a close eye on your Iris after a mild winter and work to identify the disease at its earliest onset, removing infected plants as soon as you notice them.
How To Treat: While there is no cure for this disease, there are measures that can help to control the spread of the bacterial leaf spot on Bearded irises.
Because the disease can be transmitted via garden tools and water, always be sure to wash your tools with a 10% bleach/water solution after dealing with infected plants. Remove any diseased plants and dispose of them in the trash or municipal compost center, but avoid adding them to your home compost.
Fungal Leaf Spot (Disease)
How To Identify: Fungal Leaf Spot appears somewhat similar to Bacterial Leaf Spot, but the small oval spots on the leaves do not grow in size. They do, however, form a distinct red/brown border. This disease is prevalent in wet, rainy weather so be sure to pay extra close attention during spells of rain-filled and high-humidity days.
How to Prevent: Always give plants plenty of room to grow and be sure to divide them as they begin to spread and naturalize.
How To Treat: If Fungal Leaf Spot appears, simply cut the tops off of the affected leaves. If disease persists, you can use a natural fungicide, spraying in the fall and early spring, as a last resort.
Aphids, which are small green or gray insects, appear on the Iris leaves and suck out the leaf sap. Aphids can also spread disease between plants. (Credit Don Graham/Flickr)
How To Identify: Aphids, which are small green or gray insects, appear on the Iris leaves and suck out the leaf sap. Aphids can also spread disease between plants.
How to Prevent: There isn’t much you can do to prevent Aphids, but attracting beneficial insects (such as lady bugs) that eat these pests can be an effective solution. Marigolds are a great variety to add to the garden to help attract beneficial bugs. How To Treat: These little pests are large enough to pick off your leaves or crush between your fingers. Spraying a mixture of liquid dish detergent and water is also effective.
Iris Borer (Pest)
How To Identify: Common in the Eastern and Midwestern parts of the country, the Iris Borer can wreak havoc on your Bearded Iris. Iris Borer lays its eggs in the fall on old foliage and neighboring debris. The eggs survive the winter and hatch in the early spring, finding a home on new Iris foliage. They are often hard to identify but can be seen on the foliage, often leaving a slimy trail behind them.
How to Prevent: Keeping your garden clean and debris-free is the best way to prevent an Iris Borer infestation.
How To Treat: If you catch them before they’ve made a home in your rhizomes, simply squish them between your fingers (fun, right?)
Make a homemade soapy spray by mixing one tablespoon or less of dish soap (we recommend Seventh Generation’s Free & Clear) per one quart of water.
Plantswoman and RHS Chelsea Gold medallist, Claire Austin, knows a thing or two about bearded irises. She has grown these most flamboyant of blooms professionally for the past thirty years on her plant nursery in the beautiful Welsh Borders. Here, Claire shares tips and advice on how to produce blooming iris perfection…
1. Pick your spot
Bearded irises like a well-drained, sunny site. A little overhead shade is alright in warmer southern counties, but like many plants, they will chase the sun. Also, the rhizomes tend to rot in wet soils, such as heavy clay, so add sand or grit to increase drainage or plant them in raised beds. Bearded irises do not do well in containers, as they have a large root system.
‘Az Ap’ iris
2. Planting high
When planting bearded irises, the rhizomes need to be exposed to the sun so that the flowers for next year form. To do this, place the top of the rhizome at soil level. The most difficult situation in which to get bearded irises to grow properly can be in a mixed border. In this situation surrounding plants often grow over the rhizome.
One of the best solutions is to plant more than one rhizome of a variety and place the ends of the rhizomes together (the leaves outer most) to form a triangle. This forms a barrier preventing the invasion of other plants. There is no real need to water bearded irises once planted.
3. Divide and conquer
Every three years, divide your bearded iris clumps to encourage the plants to produce more flowers. Bearded irises are very satisfying to divide. September is the best possible month for this, whilst the soil is still warm.
Take the clump, bang off any excess soil, then with your hands gently twist the plant until the rhizomes snap apart. This is rather like snapping bits off a bar of chocolate. Once all the nice rhizomes with green tops are snapped off, throw away the old, central rhizome that flowered (or should have flowered) this year. Then cut the leaves to about the length of a hand and into a spear shape. This prevents the rhizomes from rocking out of the ground when planted.
I use a pair of scissors to do this. Now cut the roots to about 15cm (6in) long to make them easier to plant, and to stop crows dragging them out of the soil (they think that they are worms).
‘Skirting the Issue’ iris
4. From border to vase
Bearded irises make wonderful and dramatic cut flowers. You can make the flowers last longer by cutting them early in the day when the temperature is cooler and by choosing flowers where the buds are just opening. Place them immediately into a bucket of tepid water.
Like all cut flowers, bearded irises need to be kept out of direct sunlight and out of drafts, and you need to replace the water with fresh water every couple of days. Pinch out wilted flowers immediately. This is particularly important with dark coloured flowers as the ‘juices’ can mark the table surface.
Need something to display them in? We love this Fallen Fruits large old zinc vase, £8.99, Amazon.
5. Extending the flowering season
Different varieties of iris flower at different times in the season, and so you can achieve a long succession of flowering bearded irises that will bloom from late April to mid-June by planting a few different varieties.
For instance dwarf Iris ‘Riveted’ will bloom from late April to mid-May; Intermediate Bearded iris ‘Az Ap’ from late May to early June, while Tall Bearded Iris ‘English Cottage’ will start blooming early through to mid-June, and bloom again in August.
‘English Cottage’ iris
6. Leave out the mulch
Whilst many perennials love a nutritious mulch in autumn or spring, this is an absolute disaster for bearded irises. Avoid mulching at all costs, as this will rot the rhizome and will kill off your iris plants.
7. Watch for leaf spot
If lots of brown spots appear on the leaves, this is leaf spot. It appears in wet weather and usually in late summer. Spray with a fungicide and remove very damaged leaves.