Quick Qu estions
Is it essential to deadhead daffodils? David Hume, Colchester If convenient and you have the time it saves the plants wasting energy on seed production but it’s not really of any great consequence. Much more important is leaving the foliage for at least six weeks after flowering so the bulbs build up resources for next year but don’t tie it in knots. Should I prune clematis hard back in spring? Paul Stout, Devizes The only clematis that need to be cut back to within 30-60cm (12-24in) of the ground are those that flower after midsummer. Evergreen clematis, such as
C. armandii, need just a light prune to remove winter damage. Reduce stems of other clematis by half, and they’ll still flower before the end of the season. What is the cause of corky growths on the stems of my cacti? Helen Kitching, Rochdale This is corky scab and is usually the result of physiological problems associated with poor growing conditions. Re-pot affected plants in spring with fresh cactus compost and put plants in good light. In warmer months water and feed to encourage strong growth. Cut back badly damaged plants to 10cm (4in) and re-pot. How can I recognise hellebore black death? Jane Collins, by email Older foliage on hellebores typically shows damage from fungal leaf spots, comprising circular areas of brown or dead tissue. Simply prune off old leaves, ideally early in the new year, before the fresh foliage shows. Black death virus spread by aphids is far more serious and shows as areas of black tissue following the leaf veins, often with severe distortion of both new leaves and flowers. Dig up and destroy infected plants.