It’s the season of dead-heading, snipping back spent clusters of rose flowers to a decent bud. Most varieties will flower again, many of the old ones not. Leave alone varieties that make good hips, such as Rosa glauca and moyesii, rugosa.

The flowered pink pokers of Persicaria bistorta ‘Superba’ can be snipped off at the base, then a second flush will follow.

Euphorbia robbiae’ is a tower of strength in dry shade under trees, opening its lime-green towers in spring. But now those spent stems need cutting off at the base, leaving the younger stems to build up to flower next spring.

Wear gloves: some people are allergic to milky euphorbia sap and it stains the skin brown.

The perennial cornflower Centaurea montana will have laid down its stems (probably mildewed) and given up. Cut them back to the crown and a fresh canopy of foliage will appear.

As mint comes up to flower, cut back the stems by half to keep fresh new shoots available.

Chives have finished flowering and the tufty heads turned brown. Either snip them off (laborious) or shear the whole plant to the ground. They will reclothe themselves in no time. In that leafless condition they can be divided — just the thing for making an edging beside a cottage garden path.

The season for phlox and eupatorium flowers is much shortened by drying out. See that they do not lack for water in dry spells.

New lawns grown from seed are strong enough now to take a dose of selective weedkiller where they are being overwhelmed by broad-leaved weeds.

Capsid bugs can destroy the flowers on phygelius and fuchsias; look out for shrivelling, aborting shoots and tiny holes in the newest leaves.

The control is bifenthrin.

Explore Gardens

• Hampton Court Palace Flower Show

• Chelsea Flower Show

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