We’ve all seen bad pruning jobs: the hedge with the big bare spot; the shrub that now resembles a Charlie Brown Christmas tree; the Camellia that never blooms, because each year it is pruned heavily in the fall late on a Sunday morning before the football game starts. Pruning is tempting yet taunting. Avoid a bad haircut; know your plant, and prune with a plan.
First off, if you don’t know what kind of plant you’ve got, don’t prune it. Get your plant identified; right now may be the wrong time of the year to prune it. Take a sample of your plant to an independent garden center to have it identified.
Most reasons for pruning fall into three groups: (1) removing dead growth, (2) controlling overall size or shape, and (3) pruning to increase flower and/or fruit production. Boredom should not be a reason to prune.
1) Begin pruning by removing any dead stems and leaves; this can be done any time of the year. It is best to prune deciduous trees and shrubs while dormant and the leaves are gone. If you’re unsure whether stems are dead, gently scrape the bark of a small stem with your fingernail or knife. If it’s green just under the bark, it’s still alive.
2) When pruning to control a plant’s size or shape, we must have a size or shape already in mind, before we begin to prune. Some older shrubs or hedges (e.g. Eugenia, Lantana) are bare in the central part of the plant. If heavily pruned, the bare center is exposed and may not leaf out right away. A hedge that has not been pruned for a few years, may end up looking pretty bad after a hard pruning.
For more formal pruning, step back and look at the plant between cuts. The plant appears much different up close versus from 20 feet away. Ask yourself which one branch or part of the plant is too big or “in the wrong place“; then prune just that one branch or part of the plant. Step back, ask yourself the question again, and repeat the process. I find this a helpful structured method to slowly change the shape or reduce the size of a plant.
3) Pruning to increase flower production begins with knowing when a plant flowers, and how the plant grows and flowers; that is, does it bloom on new growth or does it bloom on last year’s growth. One rule of thumb is to prune right after flowering, except fruit trees – see below.
Plants that bloom on last year’s growth, like Camellias should be pruned right after all the flowers have fallen off. Pruning in fall removes the flowers buds for the next year. Plants that bloom on new growth, however, like Buddleia, Hibiscus, or Caryopteris, can be shaped or pruned to size in spring as new growth begins. They also may be pruned after blooming.
Small, evergreen, flowering plants like Lavender, Germander, and Heather/Heath should be pruned each year after blooming to maximize flower production for the following year, and to maintain a neat, tidy shape.
The timing rule of pruning after flowering, however, does not apply to fruit trees. Here it is especially important to know your plant. Different fruit trees and berries are pruned differently depending on their growth character. While we lack space to fully cover fruit tree pruning, try to understand the goal or plan for pruning your particular fruit producing plants. It’s not always obvious how to correctly prune them, but knowing specific and planned pruning techniques will greatly increase your fruit production.
For more information, try books like:
Pruning Made Easy, Lewis Hill
How to Prune Fruit Trees and Roses, R. Sandford Martin & Ken Andersen
Know your plant, prune with a plan, and make sure you’re having fun!