Plant experts Matthew Biggs and John Hoyland explain what the Chelsea chop is, how to do it, and which plants to try it on.
Many plants need cutting back at points during the year, or deadheading as their flowers fade. But some plants benefit from a different technique, too – the Chelsea Chop.
What is the Chelsea chop?
For many years British nursery owners and gardeners have cut down late-summer flowering perennials in May before they flower in order to produce a more compact plant. Sedums, helianthus (perennial sunflower) and rudbeckias are notorious for flopping over in late summer. Cutting back their stems by two thirds in May produces plants that are more compact, do not slump and do not need staking. This tried-and-tested technique has become known as the Chelsea Chop.
The American garden writer Tracy DiSabato-Aust has described pruning a wide range of perennials in a similar way, to produce shorter or later-flowering plants. Many British gardeners are experimenting with her ideas to see how they adapt to our conditions.
Doing the Chelsea chop means that flowers are smaller and later, but greater in number. It’s a useful way of extending the flowering season.
When to do the Chelsea Chop
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As its name suggests, it’s something you should do around the time of the RHS Chelsea Flower Show, from late May to early June.
How to do the Chelsea Chop
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Cut back the stems of herbaceous perennials by a third to a half using shears or secateurs (secateurs are more precise).
Pruning closer to the flowering time increases the delay in flowering, as regrowth takes longer. If you have several clumps of one cultivar, cut each group back to varying degrees. If you only have a single drift then cut those at the front back harder than those at the back. Then deadhead to produce more flowers.
Which plants to Chelsea chop
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- Anthemis
- Achillea
- Asters
- Campanula
- Echinacea
- Helenium
- Helianthus (perennial sunflower)
- Nepeta
- Phlox
- Penstemon
- Sedum
- Solidago