Pruning is an art form. Unfortunately, many gardeners haven’t acquired the basics, let alone mastery. So, let’s start with the basics.
Understanding how to prune requires an understanding of how plants grow, plus a little plant taxonomy. Don’t panic… those of you who shy away from biological terms. This will be Pruning 101. Determining where and/or when to make a cut will help create the future shape of your plants. Some cuts are made near a growth bud. The subsequent growth varies, depending on the location of that bud. There are three bud types.
Terminal buds grow at the tip of a shoot (branch), and are what cause the branch to grow longer. There is a “messenger” chemical produced at the site of that bud, a hormone, that travels down the stem and tells other buds lower on the stem “Don’t you grow, I”m busy here making the branch longer!”
Lateral buds are located along the branch at leaf attachments. Their job is to produce sideways growth that makes the plant bushy. But remember, these buds will stay inactive as long as the terminal buds are busy adding length to the branch. They can be activated, though. If the terminal bud is cut off, there is less of that “messenger” chemical (hormone) and the lateral buds will come out of dormancy and begin to grow.
Latent buds are lying quietly and dormantly underneath the bark. If a branch is broken or cut off near a latent bud, another branch will grow.
There are four main types of pruning. (This is fun, isn’t it!)
Thinning, sometimes called ‘lacing,’ opens up a plant and stimulates the least amount of regrowth. These cuts direct growth, eliminate competing or old branches, and reduce the overall size of your plant. Thinning removes cross-branching to eliminate branch competition and allow for better air circulation. When thinning, you are removing an entire branch back to the ‘parent’ branch from which it grew; you are NOT cutting a branch mid-way down its length. This technique reduces the build of a plant without stimulating new growth.
Heading removes just parts of a branch, not the whole branch, as in thinning.These cuts can be made back at a bud, or to a twig that is too small to take over a terminal bud role. Heading stimulates the clustered growth of lateral buds just below the cut. Can you picture the result? It will make the plant more bushy. Initially, the plant will be smaller. However, that won’t last for long. That “chemical messenger” will initiate lots of new growth from the lateral buds in very short order. This technique will ruin the shape of a woody plant. Use this technique when your goal is to induce that vigorous branch growth… maybe in a bare spot on a tree, or to increase blooms on a rose bush, or rejuvenate old shrubs. Save it for those situations.
Shearing is an indiscriminate form of heading and does not involve cuts being made at a growing point (bud). It is indiscriminate cutting back to create a smooth surface (be it squared or rounded) on a plant (think ‘topiary’). Some plants lend themselves to shearing – such as abelia or boxwood. Other plants do not tolerate this type of pruning, and will become unhealthy over time.
Pinching is the removal of the terminal bud to stimulate lateral branching and increased flowering. This is commonly used with annuals and perennials. It can be done with your fingernails or dead-heading clippers.
So there you go. Your “Pruning 101” lesson. Most pruning in our gardens will be done in fall and winter. Proper pruning is essential in a good health plan for your plants.