The border year

A border changes through the year, and a few jobs at the right time keep it looking its best. In this lesson: staking, deadheading, the Chelsea chop, tidying for winter, and dividing perennials.

Tall perennials with big flowers often flop after rain or wind, so stake them early in spring, before they need it. Twiggy pea sticks pushed in around a clump, or metal grow-through supports, work far better than tying a plant to a cane after it has fallen. Plants grow up through them, and the supports are soon hidden by leaves.

At the end of May, around the Chelsea Flower Show, cut back some late-flowering perennials, such as sedums, heleniums, phlox and echinaceas, by up to half. They grow back shorter and bushier, need less staking, and give more, smaller flowers a little later. Cut just the front of a clump, and you spread the flowering over a longer season.

In autumn, cut back perennials that collapse into mush, and anything diseased. But leave plants with good seedheads and grasses until late winter or early spring. They look beautiful with frost on them, feed birds, and shelter insects through the winter. Cut everything down before the new growth starts in spring.

Every few years, clump-forming perennials get crowded, with a dead centre and fewer flowers. Divide summer-flowering ones in spring or autumn. Lift the clump with a fork, then pull it apart by hand, prise it with two forks back to back, or cut tough crowns with a spade. Replant the young outer pieces, with three to five healthy shoots each, at the same depth, and water them in.