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Prune wisteria and climbing shrubs such as Pyracantha after flowering.
Hebes and lavenders can be given a light prune after flowering.
Rambling roses can be pruned now, once they have finished flowering.
Give hedges a final trim over now. They will only grow a little before cold weather stops growth.
Get in qualified tree surgeons to remove large shrubs and trees that were casualties of winter waterlogging and summer drought. Remove stumps wherever possible, as rots could spread to other plants.
Continue to deadhead shrubs, such as roses, to extend flowering into early autumn. Spindly specimens that have lost leaves can be cut back a little further when deadheading, to encourage new growth.
Thoroughly soak drought-stressed plants and shrubs, especially newly planted ones. Use grey, recycled or stored rain water wherever possible.
Keep early-flowering shrubs such as Camellia and Rhododendron well watered during dry periods to ensure good flower bud initiation.
Semi-ripe cuttings can still be taken to propagate many common garden shrubs (e.g. box, Ceanothus, lavender).
Rhododendrons, azaleas and Clematis can be propagated by layering.
Brown patches, needle loss and sooty mould on spruce (Picea) trees are evidence of green spruce aphid damage earlier in the year.
Mid to late August is a good time of the year to apply biological controls for vine weevil. Grubs will be starting to hatch and soil temperatures are now suitable for the nematodes to be effective. Target vulnerable plants such as Rhododendron, Camellia and containerised plants including fuchsias.
Black spot on roses is very common at this time of year, and spraying will no longer be effective. Clear fallen leaves and burn them to prevent spread.
Powdery mildew can be a problem in dry summers.
Leaf drop, disfigured and damaged leaves can be a symptom of weather damage.
trees and shrubs
Things to do in the garden this month
Trees and shrubs
Greenhouse, conservatory and houseplants
The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.