The Chelsea Chop

Despite its name, the Chelsea Chop isn’t the latest trend in hair styling although trimming the unruly and the straggly certainly is involved. It is a very simple and straightforward method of cutting back herbaceous* plants which, for some reason, terrifies even the most confident of gardeners.

Sedums (foreground) growing at Lytes Cary Manor

The only skills required are courage and the knowledge of exactly when to carry out the chop. The latter is simple to calculate and is hinted at by the title of the deed – the week of the Chelsea Flower Show or thereabouts. This year, there have been two hiccups in using this rule: firstly, the show has been moved to autumn because of Covid restrictions and secondly, because spring has been so slow in coming that plants are behind with their growth. As a general rule of thumb, the time for cutting is around the third week of May.

The flat flowerheads of sedum are made up of hundreds of tiny star-like florets

Beloved by bees and butterflies, Sedum – also known as Ice Plants on account of their fleshy, cool-to-the-touch leaves – are the ideal candidate for the chop and one of the most satisfying to do. Inevitably, when left to their own devices, the large, flat flowerheads are too weighty for their stems and they topple over to sprawl across the ground and spoiling an otherwise impressive display.

Sedum, the Ice Plant, frequently collapses & looks ugly just as it flowers

To make the chop all that has to be done is to cut through every growing stem, thereby reducing the plant’s overall height by half to one-third. Clear away the prunings (which can be added to the compost heap) so as not to attract slugs. There, I told you it was simple!

Sedum given the chop. Don’t forget to pick up all the prunings!

Although the method sounds and looks drastic the plants quickly recover and make new growth. The end result will be a plant that doesn’t collapse and doesn’t require staking. Admittedly, the flowerheads will be smaller than before but they produce so many more than they would have done left unpruned that the effect is in no way diminished.

Numerous flowerheads appearing on the now tight growth of Sedum two months after the Chelsea Chop

This simple pruning technique can be used on a number of other plants too in exactly the same way. The taller achillea, phlox, campanula, asters (michaelmas daisies) and rudbeckias are all good candidates. I have heard of its use on echinacea (cone flower), penstemon and helenium but, in my experience, these are trouble-free plants anyway, so why bother? The secret to good, stress-free gardening practice is to find the balance of what suits you and what suits the plant. The Chelsea Chop on sedum in May prevents an awful lot of stress later in the year!

top left – clockwise: achillea, campanula, aster, rudbeckia. They can all be given the Chelsea Chop

*herbaceous – a non-woody plant that dies back and becomes dormant in winter to regrow each spring