If you’re getting stir crazy and you just have to do something in the garden, I have a job for you! Gather your cutting tools and go out to shear your herbaceous (non-woody) perennials and prune your deciduous woody shrubs. Don’t worry, i’ll tell you how. A couple weeks back I wrote about pruning fruit trees. Like pruning fruit trees, an early spring ornamental shrub pruning can satisfy the itch to spend time in the garden when you can’t dig or plant yet, (or there is still 2 feet of snow on the ground).
Pictured below, hedge clippers are for giving haircuts to your herbaceous perennials, or for selectively shearing off leggy shoots on your woody shrubs to keep them neat during the growing season. (I discuss why toward the bottom of this post, with the illustration showing Conventional Shearing vs Sustainable Pruning.) Shearing herbaceous perennials is pretty straightforward. Its like giving a buzz cut to the plant. At the end of the growing season, or before the start of the new one, shear all the remaining stems back to the base of the plant, to allow new leaves and stems to poke through.
Pruning your beloved shrubs takes some bravery. Many people are intimidated by this chore, thinking that cutting = killing. Not so! It is quite the opposite for most woody shrubs. Prepare to be shocked!
When exactly do you prune any given flowering shrub? A good rule of thumb is: allow 3 months between pruning and the flowering time of the plant. The dormant winter months don’t count. So, a March or early April pruning allows enough time for a summer-flowering shrub like Hydrangea to set new flower buds. You can prune spring bloomers like Forsythia, Rhododendron and Lilac right after they flower, and they’ll have enough time to set new buds and flower the following spring.
How much are you supposed to cut off the plant? This photo shows a Spirea shrub in the process of being cut (“stooled”) all the way to the ground using hand pruners. See the pale beige-ish round stem ends by the blade? The stems are now about 3 inches long. Are you shocked yet?
Look how nicely this Rosa rugosa recovered. This photo was taken later in the season when I stool-pruned in early spring. Stooling means cutting all the stems back to 3-6″ above the base, before the shrubs leaf out. The response will be a spray-like fountain of new growth full of flowers.
The following deciduous shrubs can be pruned (stooled) anytime from late March to about the 2nd week of April, without sacrificing this year’s blooms.
Barberry (grown for foliage)
Buddliea aka Butterfly Bush
Burning Bush (grown for foliage)
Caryopteris aka Blue Beard
Cornus stolonifera (aka Redtwig Dogwood-grown for its bright red stems in winter)
Cotinus aka Smokebush
*Hydrangea paniculata (the “cone shaped” flowering type)
To prune Hydrangea paniculata and Rosa rugosa, which all flower in mid to late Summer, first cut out the oldest (thickest) stems, dead stems and crossing stems all the way to the ground, then cut back the remaining ones to between 12-18″ from the base, leaving at least 2 pairs of buds on each stem remaining. The result will surely look like you’ve killed it and its never coming back. Don’t despair! Your shrubs will reward you with renewed vigor, glossy new leaves and flowering buds.
*A note about Hydrangea macrophylla- (aka Mop head or Lace cap Hydrangeas and the blue- flowering varieties) These flower on 2 year old wood, so you have to prune differently. Rather than pruning all the stems back to 2 sets of beds, prune only those that are weak, damaged or still have old flowers attached to them all the way to the ground. Shorten the remaining young (1 year old) stems back to about 2 feet.
Conventional Shearing vs Sustainable Pruning: Whatever you do, resist the urge to shear the outermost growth of your shrubs. All this does is promote twiggier branch ends, which result in light not reaching the center of the plant, which eventually = plant death. So leave the shears sheathed and sharpen your loppers and pruners instead! See pic below for the difference between shearing branch ends, and pruning them.
Along with pruning, I like to sprinkle a balanced fertilizer around the base of the plant at pruning time to stimulate growth of flower buds. Go the extra mile and give your plants a top dressing of home made compost too, to enrich and condition the soil to benefit all the micro organisms living in the soil.
What are you pruning now? Do tell!
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