Rose and dahlia care
Ruth shows how to keep these popular plants healthy
ROSE and dahlias are late summer garden stalwarts and with the right care, most of them will flower until autumn. The exception is rambling roses that flower in one burst and then form their hips. All you need to do to them now is remove any dead and diseased wood back to healthy growth, deadhead, leaving some hips for the birds and winter colour if you wish, and tie the stems back to keep them orderly.
As with all roses, keep an eye out for black spot and cut away and dispose of any infected material. Do not add it to the compost heap as the spores will thrive in the damp, warm environment and go on to contaminate elsewhere. While you are deadheading and removing any plant material affected by blackspot, also look for pests. Aphids will suck sap from tender young shoots and buds, weakening the plant and potentially spreading disease. If groups are small, wipe them off with your hands or leave them for natural predators (birds and the larvae of ladybirds, lacewings and hoverflies), otherwise treat with an organic spray if there is a large infestation. Organic pest sprays include Bug Clear Gun for Fruit & Veg, Westland Bug Stop and Neudorff Bug Free Bug and Larvae Killer.
Large rose sawfly is another problem. Adults lay their eggs in soft young stems and the yellow and black larvae emerge, splitting the stem, to feast on leaves.
The damage is unsightly rather than devastating to the plant, so it is best to either pick off the grubs by hand or leave them for the birds and other predators.