The garden has burst into bloom. In May and at the beginning of June the flowering shrubs, many with only a hint of green for leaves, bloom. Forsythia with their yellow flowers stand out among the whites and pinks of Nanking cherries and double-flowering plums, and the whites, pinks, and purples of lilacs. Forsythias are some of the earliest blooming shrubs. Haskaps are also an early blooming shrub with yellow flowers, but their blooms are much paler than those of a forsythia. Haskap blooms are often hidden under the plant’s leaves as the leaf is more fully formed when the plant blooms and the flowers hang down. Ninebark, dogwood, and cherry shrubs also bloom in spring. The list goes on.
While dead and damaged branches can be removed at any time, pruning for shape or rejuvenation should happen after the shrub has stopped flowering and the blooms are beginning to fade. This usually happens in June.
It is important to remove unwanted branches just after the blooms fade and before the shrub starts putting energy into fruit production to have that energy directed to new growth and bud setting for next year. Yes, the buds for flowers and leaves start to form a year in advance. Pruning later can still benefit the shrub by improving air circulation, but what is removed will not be replaced. Lilacs, a great plant for Calgary gardens, bloom from late May to mid-June. The pruning rule holds for lilacs, too. Prune them after the flowers fade. Some gardeners like to deadhead the spent blossoms, which can make the shrub look tidier, but it is not necessary.
While some gardeners think it enhances next year’s blooms, a visit to an abandoned homestead with lilac shrubs planted long before the home was abandoned, will show that lilac will still bloom prolifically without being deadheaded. So, if you have the time and can reach the ends of the branches, go ahead and deadhead your lilac, just don’t feel it’s a required garden task. Shrub lilacs can be shaped into tidy multi-stem plants or hedges. Miss Kim lilacs, with their smaller flowers and leaves, are often used for low hedges. Pruning for these features should be done shortly after flowering. This will allow time for the plant to put on new growth and form buds before fall. Pruning suckers out should wait until fall so that the pruning doesn’t encourage new suckers to form.
We may not think that conifers need pruning but if you want to ensure that the conifer has a full look or want to manage its size, then they should be pruned in June. It is often recommended to use candling techniques to manage the size of Mugo pines. What that means is the candle, the new growth, is broken or snipped off at a third or half its length. Also remember, if you purchase a plant labelled as dwarf, it means it is smaller than typical for the species. Read the tag for the mature size to determine how big it will grow—dwarf can still be too big for the space you want it to live in. While size can be managed with pruning, it is always best to read plant tags and select shrubs with a mature size that suits your yard.
Except for woody plants that have a spring sap run, birch for example, most shrubs can be pruned year-round, but there are tradeoffs. You will forfeit some of next year’s flowers and fruit on spring blooming shrubs if they are pruned later in the year. To learn more about gardening in the Calgary area visit www.calhort.org.
