Control the timing and size of your flowers
Gardening’s full of oddly-named techniques, and to the beginner, none more so than the Chelsea Chop, which sounds like an English martial art. However, it’s an easy way to get more flowers later in the summer and control the size of your herbaceous perennials (the plants my mam said ‘come back every year’).
It’s called the Chelsea Chop because it is usually carried out around the same time as the RHS Chelsea Flower Show – the end of May and the beginning of June. Being a pruning method, all you’ll need is a sharp pair of secateurs or hedge trimmers.
Most late-flowering herbaceous perennials are suitable, including:
- Anthemis tinctoria
- Echinacea
- Helenium
- Phlox
- Rudbeckia
- Tall Sedums like Herbstfreude
- Solidago and
- Helianthus.
Here’s how Birmingham Botanical Gardens’ borders look in September:
The basic rule of the Chelsea Chop
Many other late summer and autumn-flowering perennials can be cut back now. The basic rule of thumb is the closer to the flowering time you prune, the greater the delay in blooming.
Some herbaceous perennials can be cut back by as much as half:
- The plants are shorter and stockier
- They need less staking
- Flowers are smaller, later, but more plentiful
By chopping plants back and removing the top shoots, the side shoots branch out, making the plants bushier. As long as plants are fed and watered regularly, beds and borders will look tidier and fuller with more flowers. Below is how the Helmsley Walled Garden in North Yorkshire looks in late summer and early autumn. These pictures were taken in September.
How to do the Chelsea Chop
- Displays of herbaceous perennials can be cut back by one-third to a half using hedge trimmers or secateurs. This will delay flowering in the whole clump.
- If you have several patches of one plant, you can cut back a few and leave others, which will prolong the overall flowering period.
- Another way to extend the flowering season is by cutting back half the stems at the front of the clump.
- Warning: if you see flower buds already formed on a plant, the likelihood is that if you cut them off, you’ll lose that year’s flowers. Unlike repeat-flowering plants like roses, most herbaceous perennials have a one-off flowering time.
For more information on herbaceous perennials, visit the Hardy Plant Society’s website at www.hardy-plant.org.uk.
