Eleanor Clarke
GARDEN DESIGN
The Chelsea Chop: What, Why, and How
If you’ve spent any time in gardening circles, you may have heard the phrase “The Chelsea Chop” bandied about – and no, it’s not the name of a new hair trend. It’s a clever technique used by gardeners to rein in unruly perennials, prolong flowering, and encourage bushier, healthier plants. The timing? You guessed it, right around the time of the RHS Chelsea Flower Show, hence the name.
Let’s break down the what, why, and how of this brilliant bit of horticultural know-how.
What is the Chelsea Chop?
The Chelsea Chop is a method of pruning herbaceous perennials in late May (often the last week), just as they’re entering a growth spurt. The idea is to literally chop back some or all of the new growth, reducing the plant’s overall height and encouraging more compact, bushy growth.
You can chop back by about a third to a half, either across the whole plant or selectively on a few stems. It might feel a bit brutal at first, but don’t panic. The plants are perfectly capable of bouncing back stronger and better.
Why do it?
There are several great reasons to try the Chelsea Chop:
- Prolong flowering – Cutting back delays the bloom, giving you colour well into summer and early autumn.
- Avoid floppiness – Plants that tend to flop or collapse under their own weight are more likely to stay upright and tidy.
- Encourage bushier growth – The chop can help prevent legginess and encourage more flower-bearing stems.
- Stagger blooms – If you selectively chop some stems and leave others, you can create a lovely, layered flowering effect.
Echinacea and achillea
When should you do it?
The clue is in the name – aim to do it around the time of the Chelsea Flower Show, which typically takes place late May. That said, you can get away with it in early June if needed. Just make sure the plants have put on enough spring growth to make the cut worthwhile.
Top Tip: Always use clean, sharp secateurs or shears. Blunt blades can damage stems, leaving plants vulnerable to disease. Give your tools a quick clean with soapy water or a bit of disinfectant before you begin, your plants will thank you.
Which plants respond best?
The Chelsea Chop works wonders on certain perennials, particularly those that have a tendency to get leggy or bloom all at once. Some popular candidates include:
- Sedum (Hylotelephium) – Helps prevent flopping and encourages more upright blooms.
- Nepeta (Catmint) – Chopping back keeps it bushy and stops it from sprawling.
- Echinacea (Coneflower) – Delays flowering and encourages a neater shape.
- Phlox paniculata – Reduces height and gives staggered blooms.
- Helianthus (Perennial sunflower) – Encourages branching and more flower heads.
- Rudbeckia – More compact, and longer-lasting flowers.
- Achillea (Yarrow) – More floriferous and less top-heavy.
Top tip: You don’t need to chop the whole plant. Try cutting back only the front or outer stems to enjoy a tiered flowering display later in the season.
Sedum benefits from the Chelsea Chop
Plants to avoid chopping
Not all perennials are up for a haircut. Avoid doing the Chelsea Chop on:
- Plants that flower early in the season (e.g. Iris, Peonies, Aquilegia) – they’ll have already flowered or be well on their way.
- Biennials or annuals – they won’t recover in time to bloom.
- Woody shrubs – this technique is for herbaceous perennials only.
- Slow-growing or delicate perennials – they may not bounce back in time for summer.
Aquilegia is on the avoid list
Final thoughts
The Chelsea Chop is one of those low-effort, high-reward gardening techniques that can make a big difference to how your summer borders perform. It’s quick, it’s free, and it’s a brilliant way to keep things looking polished well into the warmer months.
Just remember: clean and sharp tools are your best friends. A tidy cut makes for a happy plant – and a flourishing summer display.
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