In the Garden: A time for trimming
Tuesday, June 26, 2012View full version
Do you have a lilac that only blooms up by the roofline? Was that forsythia a mass of yellow joy a few springs ago but now has only a few weak, yellow blooms? Has your rhodie gotten too big and forgotten how to bloom? All of these garden woes can be corrected with pruning these multi-stemmed shrubs.
Use the correct, sharp, clean tool. Use pruners for cuts one half inch or less. Bypass pruners allow you to cut closer to a trunk or main stem; anvil pruners are easier to use but cut by smashing the plant tissue.
For stems one half inch to one inch thick, use loppers. For stems over 1 inch thick, use a pruning saw that is thin and slightly curved to fit into tight spaces. Forcing a tool not designed for the diameter of the stem causes serious stem tearing and damage and can hurt your hands. Have all three tools with you before you start cutting.
Cuts are made at a slight angle — about 20 degrees — so water doesn’t sit on the cut and rot the stem. If the cut is too slanted, the cut cannot heal. Cut about one-quarter inch above the bud you want to grow into a lateral branch. Longer stubs invite disease and insect damage to the plant.
June is the last time to prune spring flowering shrubs because they begin to form next year’s blooms by the beginning of July. As a general rule, native bushes such as serviceberry, chokecherry or elderberry are not pruned. But the methods below will work to limit the size of these plants.
Pruning is not whacking away at the branches that are too long and in the wrong place.
The first step in any pruning job is to take out the broken, spindly, diseased or rubbing stems.
When only the ends of the branches are cut back, the pruning technique is called heading back. This technique is used to keep a shrub dense and compact — not necessarily made into a little ball (this method is called shearing). Make cuts of different lengths to retain the shrub’s natural look. This pruning is done annually immediately after a shrub has flowered. Only a few inches of plant material is removed to maintain a shrub’s particular size.
Deadheading last spring’s flowers is a type of heading back that promotes lateral branches that flower. So deadhead for aesthetics and also for next year’s flower production. Do not head back native plants; it will just make them mad and eager to get even.
So, you have been meaning to cut back that shrub, but there are so many other things to do and the loppers have gone missing. Now after a few years of neglect, the plant must be pruned differently to restore it.
Let’s talk about that lilac that blooms so high you can’t see or smell the flowers. What is to be done? It will take three years, but then you will have a totally new plant that you can head back annually. The technique is called thinning.
There are two types of cuts made on the oldest stem (the bark is gray and perhaps a bit raggedy looking).
1. Cut one third of the oldest stems to about 4 inches high. This forces the plant to produce lots of new growth at the lower part of the plant to fill in the “blank” part of the stems.
2. Cut one-third of the oldest canes to the ground. This promotes new stems from the roots of the plant. Thinning lets more light into the plant and that promotes more blooms.
The forsythia that has lost its glamour can be restored with a technique called rejuvenating. This method takes courage, and you may want to enlist the help of a trusted gardening friend to do the deed. Take a saw and cut the entire plant to the ground. Go inside and have a cup of tea. The plant will recover — this season — and likely will be filled with blooms next year. This works really well in early spring to keep buddleia under control. Use this technique as a final solution because some shrubs will pout for a year before they think about blooming again.
A WSU Master Gardeners of Chelan County column appears regularly in the Home, Garden section. Bonnie Orr is one of five columnists featured.