Cutting back after flowering

Removing spent stems tidies the border and stops the plant wasting energy on old growth and unwanted seed. On many perennials a hard cut back to the low leaves prompts a fresh basal flush of foliage and often a second show of flowers later in the season. Clearing collapsed growth also improves air flow, reduces cover for slugs and disease, and lets you mulch the crown for feeding and frost protection.

When

Cut individual stems back as soon as they finish flowering through summer. For early perennials such as hardy geraniums and delphiniums, cut them right down once the first flush fades to trigger fresh growth. Do the main tidy-up either in autumn, when growth flops and browns, or leave it until late winter or early spring (February to March) if you want to keep seed heads for the birds and winter shape. Wait until spring frosts have passed before cutting anything slightly tender.

How

Use clean secateurs or shears, or a knife for tough clumps. For a plant that has just gone over, cut the flowered stems down close to the crown or to any fresh low leaves pushing up at the base. For hardy annuals such as ammi and forget-me-not that have set seed and collapsed, simply pull or cut the whole plant away at ground level. In autumn, cut the dead top growth back close to the dormant base and clear it away, keeping any diseased material out of the compost. If you leave it until spring, cut more carefully to just above the new shoots or a healthy bud so you do not slice off emerging growth. Rake off the debris and top the plant with a mulch of compost or well-rotted manure.

Notes

It covers a wide range of soft-stemmed plants - ammi, forget-me-not, fritillary and most border perennials - so the detail varies. Hardy annuals like ammi and forget-me-not are one-and-done, so pull the whole plant once it flowers and seeds; true perennials like hardy geraniums respond to a hard cut back with a second flush; and leaving seed heads over winter helps wildlife but at the cost of a tidy border. The Chelsea chop (cutting some perennials back in late May) is a separate, earlier technique and not the same as this after-flowering cut back.