11 plants to Chelsea chop

The Chelsea chop is a useful technique that helps control the size, shape and flowering time of certain summer-flowering plants – and late-May (around the time of the RHS Chelsea Flower Show) is the perfect time to do it.

Advertisement Asters form a rich nectar source for flying insects, and respond well to the Chelsea chop.

By carrying out the Chelsea chop on your plants, you’ll also encourage the production of more flowers. After you’ve cut back your plants, make sure you give them a thorough watering and some feed.

  • How to do the Chelsea chop

Discover 11 plants to Chelsea chop, below.

1

Phlox

Cut back phlox to encourage greater production of the richly scented blooms.

2

Achillea

Achillea is very attractive to pollinators, especially hoverflies. There are many beautiful cultivars to grow, including ‘Fanal’, ‘Moonshine’ and ‘Summer Berries’.

3

Campanulas

Campanulas are known for their lovely bell-shaped flowers, in vivid shades of blue and purple. Cut them back to encourage more of the beautiful blooms.

4

Asters

Asters form a rich nectar source for flying insects, and respond well to the Chelsea chop. Asters you could cut back include Aster macrophyllus and Symphyotrichum laeve (formerly Aster laevis).

5

Echinacea

Another hugely wildlife-friendly plant, you’ll be encouraging plenty more blooms to grow by cutting echinaceas back. Keep an eye out for slugs and snails on young plants.

6

Rudbeckias

Many rudbeckias can grow so tall that they risk flopping over in windy weather. Chelsea chopping them will help to restrict their height.

7

Sedums

Sedums are prone to becoming leggy and looking untidy. Give them the Chelsea chop to encourage a neater, more compact shape, with more flowers.

8

Penstemons

With their large, tubular flowers, it goes without saying that penstemons are a hit with bumblebees. Just some of the many stunning cultivars to grow include ‘Sour Grapes’ and ‘Bredon’.

9

Heleniums

In the right spot, heleniums will rapidly grow skyward and often require staking. Cut them back to control their flowering height. Here’s how to plant heleniums in August.

10

Nepeta

By cutting back nepeta, or catmint, you’ll encourage a profusion of blooms to be produced later on, providing a later source of nectar and pollen for bees.

11

Helianthus

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Not all sunflowers need cutting back. Don’t cut back large, annual Helianthus, but instead go for perennial sunflowers, such as vibrant cultivars like ‘Lemon Queen’.

What is the Chelsea Chop

There are many plants suitable for the Chelsea Chop or for cutting down/pruning during the growing season.

Plants suitable for the early Chelsea Chop: (late May early June) include: Asters, Monarda, Lavender, Nepeta, (Cat Mint) Echinacea purpurea, Artemisia, Sedum, Phlox, Helianthus, and Rudbeckia.

Plants suitable to cut back to get a second flush of flowers: There are several Perennials plants suitable for chopping in July to encourage a second flush of flowers. In these cases cut after flowering, and feed. A second flush is not always successful, and the flowering will not be as strong. In each case just cut off the flower head stalk which have flowered to encourage side shoots. This is suitable for Hollyhock, Astrantia, Delphinium, Digitalis, Campanula, and Penstemon.

Plants suitable to cut back because of poor foliage later in the season: There are some plants where it is a good idea to cut back to get new foliage and these plants can be cut back almost to the ground, again after flowering in July. This is good where the foliage looks tatty and within 14-21 days new fresh foliage will shoot up which will look more attractive for the rest of the summer. This is suitable for Alchemilla mollis, Hardy Geranium (Cranesbill) and Salvia.

Don’t waste the cuttings; the Chelsea chop cuttings are ideal to be used to propagate new plants. The soft new growth which has been removed will make good cuttings and root very well. Sedum must be the easiest plants in the world to propagate by cuttings and to make new plants in this way. If you have one Sedum you shouldn’t have to buy any more!

If it is a Sedum it is just so easy; push the tip which has been cut off into the ground, and if kept moist it will root where it is, with no more effort than making a hole with a dibber. The other plants which have been Chelsea Chopped are also quite easy to root and are best placed in a small pot with a poly bag over to retain moisture, or in propagator away from sunlight.

It is good fun and worth experimenting with the Chelsea chop and cutting back some plants by a third, others just some individual stems by a third, or on the same plant cut some stems and not others.

Chelsea Chop is not suitable for flowers which flower only once such as Peonies, Irises and Aquilegia.

The Chelsea chop stems from the famous flower show: any plants that hadn’t made the grade would get a hard haircut, prompting a new flush of growth and, with luck, flowers. Thus something that was spent became sellable. It’s a good trick and can be employed for all sorts of perennials. It’s easy to remember, too: once Chelsea is over, start the chop.

There are a number of benefits to chopping back. Spring-flowering perennials can be persuaded to have another go – pulmonarias and Siberian bugloss (Brunnera macrophylla) are good examples. As long as the plant hasn’t set seed (and this is key), it will flush with new leaves and try to flower again. Bergenias that have just finished flowering can be given a similar haircut. Have a go with wallflowers (both the normal biennials and the perennial ‘Bowles’s Mauve’). Be hard but kind: follow with a good soak and a little feed or mulch.

Chop back now to limit overall height and manipulate plants into a compact, bushier shape that is less likely to flop at the end of summer. Choose late-flowering perennials for this method. If you were to attack something that wants to flower in June, it’s likely to sulk, and though it would recover, you’d miss out on flowers altogether. However, plants that flower in August and September have plenty of time to reboot. In fact, for these plants a light chop now is no different from being munched by a herbivore.

Plants that respond best to such treatments tend to be prairie or meadow plants that have evolved to be eaten at some point. Heleniums, asters, eupatorium, rudbeckias, echinacea, sedums and the milky bellflower (Campanula lactiflora) are ideal.

Chop back by a third, though take the tallest back to half. The harder you chop, the smaller the flowers, though you often get more flowers as a result. It does involve some experimentation – soil, aspect and rainfall will all affect regrowth.

You can’t go wrong with sedums, either ice plants (Sedum spectabile) or orpine (S. telelphium). Pinch both back by half and the result is a sturdier plant that won’t flop to show its unsightly middle. Likewise Phlox paniculata responds well to being cut back by a third.

Be pretty brutal about it and use shears if you’ve got large spaces to tackle, or carefully snip through: the results tend to look identical. Or get fancy and try a layered look, cutting the front of the clump lower than the back, effectively making the plant stake itself.

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Extend the season of blooms in your garden by taking secateurs to your perennials. Using the Chelsea Chop, you can get twice the flowering from your perennials and enjoy your garden twice as much!

Here’s how to get more blooms with the Chelsea Chop:

What is the Chelsea Chop?

The Chelsea Chop is a pruning method that will delay flowering in summer perennials and create more compact plants. By cutting back all or part of the plant you can get plants that flower longer and later into the year. Doing the Chelsea Chop for Rozanne® and other perennials will allow her to flower later and for a longer season.

When Should I Chop?

The Chelsea Chop gets its name from the RHS Chelsea Flower Show, which happens in late May, early June and is when the Chelsea Chop should be carried out in your garden. You can also take your shears to some perennials in July to encourage a second wind of flowering.

Easy How-To

There are two ways to carry out the Chelsea Chop, depending on your courage, and the look you want to achieve. You can cut the entire plant back, or you can trim one-half to one-third of the stems.

Trimming the entire plant will create a more compact plant that will produce more flowers later into the year. To chop this way, simply grab your shears and begin chopping. Cut off about one-third to one-half of the plant.

For plants with multiple stems, or if you want to create a staggering flowering look, chop some stems off the plant and leave others. The part that hasn’t been chopped will flower first and then the chopped part will flower later, prolonging your flowering season.

More Resources

You can do the Chelsea Chop on certain plants to get new foliage and others to get a second flush of flowers. Doing the Chelsea Chop can also help keep taller plants shorter and less likely to grow unruly and fall over.

If you’re a little hesitant to chop away at your lovely plants, there are other seasonal pruning methods you can use to keep your blooms lush and healthy.

How brave are you with your secateurs? Have you tried the Chelsea Chop?

To Chelsea chop or not?

1 Clever cuts, more flowers

If a full-on Chelsea chop seems a cut too far, there’s a middle way which can work with any plants that flower on this year’s growth. Cutting back around a third of the shoots of multi-stemmed perennials by half means you’ll get early flowers, and then plenty more later on as the pruned shoots catch up. Try this with sneezeweed (helenium) or herbaceous phlox.

Buddleia and lavatera respond similarly if you leave around a third of the old shoots intact, rather than hard-pruning them all in spring. Flowers appear on last year’s shoots first, which are followed by those on this year’s growth.

As the main, towering spikes of hollyhocks, foxgloves and delphiniums fade, they will all send up a later flush of follow-on flower spikes if the old spike is chopped off just above the developing sideshoots. This also helps curtail over-enthusiastic self-seeding.

2 Bedding unleashed

Packs of bedding plants on sale now have been tailored for maximum wow-appeal. This is why many of them, such as French and African marigolds, often reach their “point of sale” with a lone single flower atop each plant. Below this you’ll find embryonic shoots and flower buds, filled with pent-up potential, ready to be unleashed. Pretty it may be, but that first bragging flower which lures you to the checkout needs nipping out. Freed from its dominance, the young plant will branch and spread, producing plenty of shoots and copious flowers.

3 Cut-and-come-again

Pots of “salad leaves” can give two, three or even more succulent pickings, but there’s a simple knack needed to achieve non-stop cropping. When the leaves are 2-4in (5-10cm) tall, gather a bunch in your hand and use scissors to behead the young plants to a half-inch (13mm) above the base of the leaves (never cut below them). This cleanly removes the young salad, but leaves the growing point of each plant intact to resprout. Do the same with pea shoots and you’ll enjoy them for weeks on end.

4 Chop and mulch

As my new beds take shape, I dig or disturb them less and less. Growing living “green manures” suits my digging-averse approach. Research has shown that the brassica rape (the one that turning entire fields yellow around now) is one of the best green manures for boosting soil’s organic matter content, so I’m using it to build up a narrow strip of indifferent soil.

After sowing it late last summer, I recently reached for my shears to chop it down, into small pieces, before covering it with a mulch of leaf mould.

Both the leafy tops and the fibrous roots will rot down and be incorporated by earthworms. Most green manures can be treated similarly.

5 Short back and sides

Aubretia is a plant you can take your frustrations out on – and it’ll pay dividends. These tumbling cushions from the cabbage family will be starting to look pretty scrappy by now, so it’s time to go a-shearing. Chopping back all the flowered shoots removes the faded flowers and promotes fresh new growth that’ll flower prolifically next spring. Treat perennial alyssums in the same way, and keep your shears at the ready and give lavender a similar once-over when flowering’s over – but don’t cut back into old, brown shoots.

6 Off with their heads

One vegetable which responds exceptionally well to being chopped off is calabrese/broccoli. Once the main head has formed, cut it cleanly away, but don’t be in a hurry to pull the plants up. Removing the main head triggers the growth of sideshoots, each producing a mini head of tightly-clustered flower buds. Pick these and even more small heads follow. Then some more.

I’ve had great success with the broccoli/kale hybrid Brokali F1 ‘Apollo’, with its thick, juicy stems. It’s easy to raise from seed, quick-growing and responds well to regular cutting.

7 The “Hampton Court chop”

My astrantias are looking pretty shabby and flowered-out by the time of the Hampton Court Palace Flower Show, in mid-July. Nepetas, hardy geraniums and many other perennials will be flagging by then, too. To trigger a flush of new growth and perhaps a late burst of blooms, cut plants back, almost to ground level, using secateurs or shears. A high-phosphate liquid feed (tomato food is fine) will give them a tonic and you’ll get fresher, neater plants to tide you into autumn.

8 When not to chop

The mild winter has left most of my pot marigolds (calendula) unscathed. They’ve undergone a resurgence in the last month, turning from clumps of brown, tattered twigs into bright green mounds bursting with flowers.

Coinciding with the first determined outings by nest-seeking bumblebees, and nectar-craving hoverflies, their timing is impeccable. The best bit is they’re flowering weeks ahead of fresh-sown plants, and any outdoor self-seeders. It could all have been quite different; scratching the stems to reveal green signs of life saved them from the secateurs.

9 Nettles: chop and brew

Now’s an ideal time to make your own all-round plant food from perennial stinging nettles. I have several clumps dotted around and they’re a forest of sappy green (and very stingy) 3ft (90cm) tall shoots. Cut now, well before they flower and set seed, chopped up into a bucket and drowned in water, they’ll rot down and produce a useful home-made (and pungent) liquid plant food in 2-4 weeks time. Filter it through some old garden fleece, then dilute one part nettle brew to 10 parts water. I use it as a weekly tonic for most plants, mixing it with a proprietary organic-based feed for strong growers. You can brew up a fresh batch when the shoots regrow.

1 Chop nettles down using shears or secateurs (wear tough gloves).

2 Cut the stems (and any roots) into 4in (10cm) lengths.

3 Firm down the chopped stems and cover with water.

4 Use a brick to weigh down the shoots as they decay.

The Chelsea ‘Chop’

Chelsea week is the one time of the year that gardening dominates the airwaves and takes centre stage in the public’s mind which is slightly curious because as any “real” gardener knows gardens are an all year round obsession that occupies one’s thoughts and efforts for 52 weeks of the year . It is that constant input and long term commitment that really produces the results and offers the rewards. I am therefore a little ambivalent about the razzamatazz of theatrical horticultural perfection, seemingly achieved in an instant, that Chelsea and other shows purvey to a ravening public desperate to be told that you can buy a perfect garden in the same way you can buy a perfect interior if you throw enough money at it. Having said that the whole show is a triumphant tour de force demonstrating huge skill and dedication from all involved in its presentation and I was oohing and aahing along with everyone else as I wandered round, just don’t mistake it for the real thing!

So fantasy aside what have we been up to at West Dean Gardens over the last few weeks? Well Chelsea has given its name to more than the Show as we now also have the eponymous “Chelsea chop”. No, this is not a karate move or a particularly succulent cut of lamb but a simple device used to reduce the bulk of and delay the flowering of a wide range of herbaceous plants such as sedums, geraniums, acanthus etc. Like most things horticultural it is not an exact operation in either its execution or timing and is dependent on a number of variables including the nature of the plant, the effect desired and the season that year. Thus this year is “early” so the Chelsea chop was in fact happening a couple of weeks prior to the event, nonetheless the name is a useful aide memoire. One of the plants that we “chop” annually are the larger Sedums such as “Autumn Joy” as left to their own devices their crowns tend to overextend themselves and then flop out from the centre as the flower heads develop. By cutting the developing crown back to about 3″ at about the middle of May they will remain much more compact and self-supporting. It’s as simple as that and well worth experimenting with anything that tends to flop in your conditions, plants are generally forgiving and rarely die because of an ill-advised intervention on the part of the gardener. However if you really want the low down on the subject there is no better guide than Tracy Di Sabato’s book “The Well-Tended Perennial Garden”, which although written for the USA market is still an exemplary guide.

That aside May is undoubtedly the “crunch” month when everything needs doing at once and even the best organised gardener begins to doubt whether everything will all get done in the right time frame. This has been a particularly balmy spring but mild temperatures, reasonable sunshine and regular showers mean that the grass is growing apace and our usual weekly cut is barely enough to stay on top of the growth, waiting until your lawn looks like a silage crop is not a good policy, once a week is! With the risk of frost past we are furiously trying to get all of our annual displays and half hardy perennial material out of the frames where they have been hardening off and into the ground. This has the added benefit of reducing the amount of time spent watering pots! Under glass many hours are being spent pruning, tieing in and deflowering the grape vines. Experience has taught us that time invested now pays huge dividends. By getting the fruit bearing framework properly trained at this stage you can then afford to be a little more relaxed when they start fruiting and reduce their growth rate. Early investment of time nearly always pays dividends in the garden.

But despite the pressure don’t forget to look up and smell the flowers! Good luck!!

Jim Buckland
Gardens Manager

What Is The Chelsea Chop: When To Chelsea Chop Prune

What is the Chelsea chop? Even with three guesses, you might not get close. The Chelsea chop pruning method is a way to extend your perennial plants’ flower production and keep them looking neater to boot. Read on to learn more about the Chelsea chop pruning method and when to Chelsea chop prune.

Chelsea Chop Pruning Method

It’s named after that huge UK plant event – the Chelsea Flower Show – that takes place at the end of May. Just so, anyone wanting to try the Chelsea chop for plants should get the pruners out and ready as May comes to a close.

The Chelsea chop for plants involves cutting back by half the stems of tall perennials that bloom later in summer. Simply get out your pruners, sterilize them in a mixture of denatured alcohol and water, and clip back every stem.

The Chelsea chop pruning method removes all the buds on the top of the plant that would have opened relatively quickly. That means that the side shoots have an opportunity to branch out. Generally, the top buds produce hormones that inhibit the side shoots from growing and blooming.

Chopping off the top half of each stalk also means that the newly-shortened plant stems won’t get floppy as they blossom. You’ll get more blossoms, albeit smaller ones, and the plant will flower later in the season.

When to Chelsea Chop Prune?

If you want to know when to Chelsea chop prune, do it in the end of May. You may be able to do the same thing in June if you live in a more northerly area.

If you balk at the idea of cutting back all the shoots for fear of losing the current year’s flowers, cut them back selectively. For example, cut the front ones back but leave the back ones, so you’ll get quick flowers on last-year’s tall stalks, then later blossoms on this year’s shorter stalks in the front. Another option is to cut every third stem off by half. This works well with plants like sneezeweed or herbaceous phlox.

Plants Suitable for the Chelsea Chop

Not every plant does well with this pruning method. Species that bloom early in summer might not bloom at all if you chop them back. Some plants suitable for the Chelsea chop are:

  • Golden marguerite (Anthemis tinctoria syn. Cota tinctoria)
  • Purple coneflower (Echinacea purpurea)
  • Sneezeweed (Helenium)
  • Garden phlox (Phlox paniculata)
  • Goldenrod (Solidago)

What’s the Deal with the Chelsea Chop?

Pretty much any gardening book that’s worth its salt mentions the Chelsea Chop—but most do only that. The introduction of the concept is usually followed by some variation of this sentence: “Cut the plants back by a third or half to delay bloom and limit size.” But the how, why, and what are rarely discussed. The Chelsea Chop can be used to great effect if you’re trying to create peak season combinations. It often allows you to ensure that plants which don’t normally bloom in tandem with each other reach their peak at a similar time. There are several other benefits too, as well as some drawbacks.

This article first appeared as a sidebar in the article Peak Season Combos in Fine Gardening Issue #188

What is it?

The Chelsea Chop is a method of pruning that limits the size, controls the flowering season, and often decreases the flopping of a number of herbaceous perennials.

When do I do it?

The Chelsea Chop got its name from the famous garden show that takes place in England in late May— which is historically when the pruning method should be used. However, depending on where you live in the country, the chopping is best done in late spring or early summer, or when the plant has a fairly substantial amount of vegetative growth.

What is the upside?

Typically plants aren’t as tall or leggy, so they may not need to be staked or supported. The flowers may be smaller but in many cases are more numerous. This happens because the removal of the top shoots enables the side shoots to branch out more.

Are there drawbacks?

You can’t do the chop on all summer-blooming plants— for instance, woody subshrubs don’t respond well. Also, if your spring has been particularly dry, performing such a drastic pruning may do more harm than good to your plants, sending them into a shock that they may not recover from.

What plants are ideal candidates?

Many summer- and autumn-flowering perennials, such as these, are perfect for the Chelsea Chop.

Left: Aster; Center: Penstemon; Right: Black-eyed Susan. Photos: (left), Carol Collins; (center and right), Michelle Gervais

How do I do it?

There are two ways to do this simple pruning.

Illustrations: Conor Kovatch

Method 1

Chop back clumps of perennials by one-third to one-half using shears. This will delay the flowering until later in summer and keep plants shorter and more compact.

Method 2

Cut only half the stems back on a plant, which will extend the season of flowering rather than delay it.

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