Pruning and Training
May is the time to cut back tender shrubs and sub-shrubs such as Penstemon, Caryopteris and Fuchsia after the danger of frost has passed. You can also trim any Evergreen hedges throughout the month. Late spring is a good time to coppice or pollard Eucalyptus and cut back young Mimosa Trees. You should now prune out any frost damage from affected evergreen shrubs.
Ensure newly planted trees and shrubs do not dry out. Water with rainwater or recycled water wherever possible.
Pests and Diseases
Viburnum beetle grubs start nibbling holes in the leaves this month, giving plants a tattered appearance.
Check roses for signs of blackspot (left), aphids and leaf-rolling sawfly damage.
Inspect sick looking box and holly trees for signs of blight.
Phytophthora root rots can cause die back on mature trees and shrubs. Wet winter weather followed by a hot spring and summer can encourage this problem on susceptible woody plants.
Caterpillars, aphids and other fly pests can all be problematic at this time of year. Early infestations can be managed by hand removal, but approved insecticides are necessary for more serious attacks.