Laidback gardening with Robert Kourik
Many people start pruning after the beginning of the year. Now is one of the times to prune, especially deciduous trees and shrubs. But a combination of summer and winter pruning may be the best for any rangy plants.
A native forest doesn’t prune itself, so sometimes we should likewise refrain, depending on circumstances. I shear my lavender heavily and religiously each year to encourage new growth. I prune my fruit trees every summer (and sometimes in the winter). I shape — not shear — Jerusalem sage ( Phlomis fruticosa) once a year, otherwise it will take up ever-increasing space in the garden. All too often we prune more than we need to, and heavily clipped trees and shrubs can look ridiculous or horrifying to a sustainable gardener.
Limbs do fall in the forest, from trees that happened to grow with a weakness. We should always prune a young tree if it needs some judicious snipping to help it get off to a sturdy start. One example is the included (invaginated) bark on the trunk of a tree. When two trunks share the same spot, the two shoots compete for tissue. The trunk cannot share its circumference in this situation, so one of the shoots will inevitably fall off or weaken. Pruning off one of the parallel shoots when the tree is very young provides a strong start for a tree that may never have to be pruned again.
I’ve made thousands of cuts on my own trees, and the properly made cuts have callused over quite nicely. But I’ve seen so many young tree trunks damaged by sunburn that I want to remind you to use paint (50 percent water and 50 percent interior or exterior latex-only paint) to cover the entire trunk up past the first few limbs on the very day the tree is planted.
Also, trees that are radically pruned — summer or winter — may need paint applied to the tops of newly exposed limbs. The need to paint can be avoided simply by making judicious thinning cuts over the course of several years.
While a proper pruning cut doesn’t need paint to form a healthy callus, some plants (such as tropical and subtropical fruit trees like avocado and citrus) are extra-sensitive to sunburn. A quick coat of the 50/50 paint-and-water mixture may prevent sun damage.
If dormant (winter through early spring) pruning for limiting size is needed, the timing of growth suppression can be useful. A timehonored tradition (especially in Europe) holds that the removal of foliage during the growing season reduces the amount of leaves available to make food for storage in the tree or shrub’s mass. This reduction in food has a gentle debilitating effect on the subsequent spring’s growth, which amounts to a mild form of dwarfing. Under this theory, more ambitious (“harder”) summer pruning equals more control over growth. Winter pruning usually stimulates growth and causes more shoots to sprout.
If the plant in question isn’t very vigorous and is somewhat small to begin with, then one pruning a year might be enough to limit its height. This single pruning could be done in winter, spring, or summer. When trying to restrain a vigorous tree or shrub, pruning is best done in winter, spring, and summer. Pruning all season long is best for controlling overgrown trees and shrubs.
Robert Kourik is the author of the new book, Sustainable Food Gardens (Metamorphic Press, 2022). To see the other 17 gardening books he has written, visit: robertkourik.com.