By Joan Weed, Contributor
As thoughts of the next gardening season are already coming to mind, I am reminded that we are approaching a good time for an important garden chore. You might think it’s something to do in a greenhouse or under lights in the basement, but no, this chore should and must be done outdoors.
March is the ideal time to prune trees and shrubs. This is when their skeletons and indeed “bones” are best noticed. The plants are still dormant and a few of the days are benign enough to venture outside for some bracing exercise. Tools for the job include secateurs, loppers and a handsaw. The diameter of the branches will help you choose the correct implement.
I recently had some professional tree surgeons take care of some dangerous, dangling limbs and also remove some pine trees. I would not have tried this on my own. For safety’s sake, it’s wise to choose the professionals for some jobs. Young trees or understory trees can be handled by backyard gardeners pretty easily.
One should be bold when it comes to pruning some shrubs. In our 20-plus years living here, our forsythia grove has been taken completely down to the ground at least twice. It returns in a few years, afresh with new growth. In between, I try to trim any extra-long branches to maintain shape while trying to keep a natural look. Lilacs are another stand-by that benefit from regular maintenance. The rule of thumb is to remove one third of the oldest trunks each year at ground level. Lilacs spring back with vigorous new growth after this treatment. In fact, after the ’98 Ice Storm, one of our lilacs was flattened completely by a fallen tree. I thought it was a goner. After cleanup it sent out new growth—and you would be hard-pressed to notice it had been a victim.
Viburnum carlesii, or Korean Spice Bush, needs regular trimming. Azaleas also need to be kept in proportion with your garden design. Yews are another variety that can grow out of hand easily. Of these three and many others, one must be careful not to trim only new surface growth (unless you are aiming at topiary).
Reach into the plant and trim where the branch originates. If one trims only the surface growth you will end up with a green shell and no growth in the middle of the shrub. Search for crossing branches or branches aiming toward the center of the plant. Cut cleanly but leave a small collar of the limb in place (about 1/2 inch). Of course, any dead or diseased branches are noticeable now too. Good time to remove them.
You might notice young whips growing among your lilacs or alongside fruit trees. In the case of lilacs, you’ll want to leave a few select healthy ones to replace what you have removed. Alongside trees, trim the competing whips to the ground. Hollies and shrub roses have similar pruning needs. Look for outward facing nubs on the stem you are working on and cut at an angle about 1/4 inch above the nub. Imagine where you’d like to see a new branch form and grow.
Another kind of pruning is called coppicing. This is where you take a plant to the ground by trimming. I have done it successfully with cotinus, red-twigged dogwood and the aforementioned forsythia.
It is important to know which shrubs can take a complete trim and which it is wiser to leave except for dead branches. The best way to learn is by attending a class or reading a book on the subject (with good diagrams) or studying other gardeners’ efforts. For example, rhododendrons are only pruned for shape or to remove dead limbs.
I hope you’ll try to manage those overgrown specimens in your garden. Be brave! Most shrubs can take a good trim now and then.