As roses, camellias, crabapples, grevilleas and a host of other flowering plants finish their spring flush, you may be wondering what should be pruned now and what should be left? Here’s a guide to when to prune common garden plants, and how hard.
The rule of thumb with most flowering plants is to prune soon after their flowers or fruit have finished, removing no more than one-third of the canopy for shrubs, and only 10 per cent for large trees (if you choose to prune your trees). Scheduling pruning in this way allows adequate time for new growth to mature before next season’s flowering. If you prune too late, the plants may produce fewer or no flower buds.
Winter-to-spring-flowering shrubs, such as lilac, camellia, azalea, rhododendron, maybush and forsythia, can be pruned now. Natives such as tea-tree can be given a light prune to shape after flowering. So can bottlebrush and grevillea, which can be given a harder prune if required.
Evergreen spring-flowering trees, such as evergreen magnolias, are best pruned lightly as soon as the petals fall and before the new flush of growth. Some spring-flowering trees, such as jacaranda, are best left alone, as they send up ugly water shoots when pruned.
Flowering deciduous trees, including cherry, plum and crabapple, are best pruned soon after their flower show has finished if they are ornamental varieties, or after harvest if they are grown for fruit. The only pruning required for apple trees in spring and summer is to control excessive growth or to remove branches growing inwards. Their formative pruning is best done in late winter when you can see the branch structure more clearly.
Roses that flower once, such as banksia roses and ‘Albertine’, can be pruned after the spring flush. Repeat-flowering roses just need a light trim to remove any spent flowers and encourage more blooms.
Herbs such as rosemary, thyme, lavender and oregano can be pruned now if they are looking straggly and unkempt. They won’t reshoot from bare wood, so don’t prune them hard. Always leave a reasonable amount of foliage below the cut.
As you go about your pruning, take the opportunity to remove dead, diseased and damaged material. This helps to maintain both the appearance and health of any plant. Also, it’s good practice to fertilise and water plants after pruning to support them as they respond with new growth.
Learn more about how to care for flowering plants, including daisies and Japanese windflowers, in the November 2020 issue of ABC Gardening Australia magazine, out now.