Weekend Work: Time to slash back early flowering herbaceous plants

What to do

Some early flowering herbaceous plants such as the oriental poppy can be slashed back to the ground now that their performance is over. The perennial cornflower Centaurea montana can also be cut back after the first flush of flowers.

New dahlia plants should be in the ground now, well protected against slugs. Thin out the growths of established plants, leaving perhaps four or five main stems to grow on; tie them to strong stakes.

Stop chrysanthemums set out last month and guard against aphid attacks.

Take out the dead flowers from lilac bushes and prune out some of the scraggier growths. Grey-leaved brachyglottis (senecio) is coming into flower now. If you grow it for the leaf rather than the flower, cut out the flower heads now.

Nip flower buds off herbs to prolong leaf production. Basil can be kept in pots on a windowsill. Feed regularly with a liquid feed high in nitrogen.

What to see

Great Dixter is holding a Great British Insect Day today (10am-1pm) with a talk on bumblebees by Dr Nikki Gammans, and information about insect-friendly plants from Professor Francis Ratnieks of Sussex University. The free event will be held in the Dixter Farm Education Rm, Great Dixter, Northiam, Rye, East Sussex TN31 6PH. To reserve a place, call 01797 254046 or e-mail education@greatdixter.co.uk