While they may not be blooming yet, spring flowering shrubs will soon be blooming. Most shrubs begin the process of producing new flower buds shortly after the current years blooms fade. You don’t want to prune them before bloom or you will lose the flowers. But be ready to prune soon after they stop flowering if you need to shape them or lower the height. Pruning may also create more vigorous blooming next year in some species.
Some flowering shrubs may not need much pruning at all. Others need pruning to keep the flower show at its best. Some shrubs simply get too large for their location if they are never pruned and need to be kept within a reasonable size. Spring flowering shrubs include forsythia, lilacs, spirea, azaleas, rhododendrons, flowering quince, some forms of dogwood and willow, Witch or winter hazel, Abelia, Oregon grape holly, Daphne, Pierus, Kerria, Beauty Bush, heaths and heathers.
Some early flowering shrubs such as bush cherries, service berries, hollies, and certain dogwoods that are prized for the colorful fruit they produce should not be pruned if you want that color show. The flowers can’t produce fruit if they are pruned off. However you may need to take off some height or width and sacrifice some fruit.
Making the cut
Make every pruning cut just above a node for the best appearance and health of the plant. A node is a joint on a stem where you see a leaf or bud. That’s the only place new growth can occur. Plants vary in how far apart these nodes are on a stem. If you make your cut too far above a node you will have little dead stubs on the end of branches for a long time. Cut on a slant just above a node and the stems will quickly be hidden by new growth.
Begin your pruning within a month after bloom has ended. Start by removing any dead branches, broken branches or branches that seriously offend, such as those sticking into paths or blocking windows. Then step back and evaluate the shape of the shrub. In most cases flowering shrubs look best when allowed to have a natural form and are not trimmed into hedges or balls. If the shrub has a naturally arching form, such as spirea, try to maintain that shape.
It’s best not to remove more than a third of the shrub when pruning. Prune back the height to about a foot below your desired height and cut back the width if needed. While pruning cut off any seed pods or dead flower clusters. Unless you want to try and grow some new shrubs from seed these seeds detract from the shrubs looks and also divert energy into seed production that could go into new flower buds.
Some shrub specific pruning tips
Abelia should have about 1/3 of its older stems removed to the ground each year as well as shaping if needed. Service berry ( Amellanchier) doesn’t have to be pruned but if it’s too large it can be heavily pruned back without much effect. Flowering Quince can have all the second year stems removed each spring after flowering to keep the plant smaller. Dogwoods don’t have to be pruned but can be shaped or reduced in size by careful pruning after flowering. Daphne is usually just shaped a little.
Witch hazel is just lightly pruned to reduce size and improve its shape if necessary. Kerria needs 1/3 of the stems cut back to ground level each year after flowering. Every third year Oregon Grape Holly should have the oldest woody stems removed to ground level. Pieris should be trimmed and shaped lightly as needed.
Forsythia should have 1/3 of the oldest, thickest stems removed each year. Thin out thickets of it and shorten if desired. If you have old, very large and thick stemmed plants you can take the whole mess down to the ground and it will rejuvenate, but it may not bloom well for a few years. Wait to trim forsythia kept as a hedge until it has flowered.
Lilacs require some additional pruning care. In order to keep lilac borer under control some older, woody barked stems need to be removed each year. This pruning is best done in winter when the plants are dormant. Remove about a third of the oldest woody stems each year if there are many. Space the stems you leave so that they don’t touch. Keep lilac suckers which come up around the plant pruned out except for one or two. You can prune for height and width right after bloom. If lilacs are seriously overgrown they can be thinned out and cut right to the ground. It will take several years before you will get blooms again after this.
Rhododendrons and azaleas rarely need much pruning in Michigan and other really cold areas. You can reduce the size if needed, don’t take off too much of the plant in any year if you want to have blooms the next year. If you do have old, very large plants they can be cut back severely to a foot or so above ground but they will probably not bloom for years afterward. Make sure to leave a couple of nodes or leaf buds on each stem that is left.
Shrubs that flower all season or in late summer and fall are best pruned when dormant.
Flowering shrubs are great investments for your landscape. They require less care, on average, than perennials or other flowers and can be selected to attract birds and other wildlife. If you visit one of Michigan’s many nurseries or garden shops you will find a wide variety of flowering shrubs available for purchase. Why not add something new this spring?
Here are some additional articles you may want to read.
Making a woodland garden.
Great native shrubs
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