What is the Chelsea Chop? EYNTK about this pruning method

echinacea purpurea, purple coneflower
What exactly is the Chelsea Chop? Bildagentur-online - Getty Images

The Chelsea Chop involves pruning herbaceous perennials to delay flowering; a process that coincides with the Chelsea Flower Show.

The cut-back is usually performed in the garden in late May (around the time of RHS Chelsea) or early June, and the general rule is: the closer to flowering time you prune, the greater the delay in flowering. Although bear in mind, the degree of cutting back is specific to each species.

The Chelsea Chop is a simple technique – traditionally employed by plantsmen in a bid to freshen up tired plants and catch late season sales – and doing so helps to control the size, shape and flowering time of certain summer-flowering plants. The process encourages bushier, stronger and more floriferous plants later in summer.

Garden writer and Gardeners' World presenter Monty Don sums it up perfectly on his blog: 'The Chelsea Chop (so called because it is done any time in the weeks around Chelsea Flower Show which has traditionally, in pre-covid days, been in the third week of May) is a way of extending the flowering season of late-flowering herbaceous perennials such as heleniums, sedums, lysimachia or solidago (Golden Rod). If you have several clumps of these plants then cut one of them about half way up the existing growth. If you have just one big clump then reduce just one third of the plant in this way. The result will be that the pruned section will produce side shoots bearing extra flowers which will bloom a few weeks later than the uncut growth and extend the display into autumn.'

solidago canadensis canadian goldenrod yellow summer flowers medicinal plant
SolidagoAlatielin - Getty Images

So essentially, by carrying out the Chelsea Chop on your plants, you'll encourage the production of more flowers and will end up with a neat and tidy flower border.

How to do the Chelsea Chop

Leading gardening charity, The Royal Horticultral Society, explain...

1. Clumps of perennials can be chopped back by one third to a half using shears or secateurs. This will delay the flowering until later in the summer and keep plants shorter and more compact.

2. If you have several clumps of one plant, try cutting back a few, but leaving others, as this will prolong the overall flowering time.

3. Another method is to cut half the stems back at the front of the clump – this will extend the season of flowering rather than delay it.

sedum autumn joy 'herbstfreude'
HerbstfreudeAlpamayoPhoto - Getty Images

'Some herbaceous perennials can be cut down by as much as half with positive results,' say the RHS. 'The plants are not so tall and leggy; they need less staking and the flowers are smaller but more numerous.'

This happens because the removal of the top shoots enables the side shoots to branch out and bear extra flowers, which then bloom a few weeks later, extending the display into autumn.

After you've pruned the plants, remember to thoroughly water afterwards.

The Chelsea Chop: plants to prune

There are certain plants that respond well to the Chelsea chop. These are...

  • Anthemis tinctoria

  • Echinacea purpurea

  • Helenium

  • Phlox paniculata

  • Sedum (upright, strong-growing forms such as 'Herbstfreude')

  • Solidago (Goldenrods)

helenium autumnale 'western mixture'
HeleniumTonyBaggett - Getty Images

If you need more advice, watch the RHS' video on carrying out the Chelsea Chop.

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