When To Prune — And When Not To: A Seasonal Guide

I know it seems a little late to talk about pruning, but this is actually a great time to prepare a pruning schedule for your garden! Pruning is an important part of caring for a garden or landscape, but planning when to do it is even more critical.

First, let me say I’m a huge proponent of picking plants that are the appropriate size for your space—so they don’t require heavy “pruning” in the traditional sense. That said, a once-a-year pruning regimen is still valuable because most plants thrive with some healthy, selective maintenance cuts that rejuvenate and revitalize them.

There are several key reasons one might prune a tree or shrub:

• Removing dead, damaged, or diseased limbs, branches, and twigs.
• Increasing plant vigor or reducing plant vigor.
• Shaping and maintaining structure.

Since my goal is to prune my plants no more than once a year, the key is knowing what type of pruning each needs—and therefore when to do it.

Late Spring

We’re into May now, so let’s talk about late-spring pruning. The plants you’ll prune at this time are generally early spring bloomers—especially evergreens—that have just finished flowering. Azaleas, loropetalums, rhododendrons, and camellias (to name a few) can be pruned now. Pruning these spring bloomers in late spring can even encourage another flush of flowers in the fall, especially in the case of azaleas. This pruning falls mainly into the shaping and maintenance category, while also increasing plant vigor as the evergreen pushes new growth and sets buds that will power next season’s blooms.

Summer

As we move into summer, pruning is generally not recommended. Plants are in full active growth, working hard at transpiration and respiration. However, there are important exceptions: Cleaning out dead limbs or otherwise compromised branches that would hinder the plant's growth and performance. This limits disease spread and allows more light into the canopy to encourage healthy new growth.  

The other exception for allowing summer pruning is to reduce the vigor of a plant.  This is a rare situation, and one that hearkens all the way back to dendrology theory in my college Arboriculture class(!). The theoretical situation we discussed was this: If you have an extremely overgrown (apricot) tree with crossing limbs and an inordinate amount of immature fruit production that is putting significant strain on the already poor structure of the tree’s branching system, you may prune the tree back by ⅓ of its total canopy in a single growing season.  This will decrease the vigor of the tree to more manageable output, though I recommend doing it only once before returning to a regular, lighter annual pruning schedule for optimal fruit production.

Fall

Fall is a great time to prune as an investment in future health and vigor. I generally don’t recommend heavy canopy cleaning at this time, since falling leaves make it harder to spot weak or non-vigorous branches. However, it’s an excellent window for pruning fruit trees and shrubs for better future crops, as well as for shaping, grooming, and maintaining ornamentals. You can also prune many evergreens in fall—just be careful with spring-flowering types that bloom on old wood so you don’t remove next year’s flower buds.

Pruning is generally not recommended in winter. It triggers a response in the plant to push new growth, but heading into extreme temperatures can cause significant dieback behind the cuts. It also takes time for these pruning cuts to heal, and if they are done at a time when growth processes are slowed way down, you risk longer vulnerability to disease, pests, and weather damage.  

Early Spring

Finally, early spring can be another excellent time to prune. As xylem and phloem processes ramp up for a burst of new growth, you can harness that energy to direct where you want that new growth to go!  Fruit trees especially benefit from thoughtful spring pruning. Stone fruits do well with “open-canopy” pruning that removes interior branches to let light reach the center. Central-leader trees (apples, pears, cherries, etc.) benefit from maintaining a strong central leader with well-spaced scaffolding branches that support fruit weight while still allowing good light penetration.

In addition to fruiting plants, species that bloom on new wood (such as panicle hydrangeas, many roses, and butterfly bushes) respond well to early-spring pruning. A healthy removal of about one-third of the old growth is usually ideal. And don’t forget herbaceous perennials! Once new growth appears, you can cut back last year’s stems and spent flower heads—but consider leaving some out a bit longer. Many beneficial insects and pollinators rely on those old stems for shelter during winter, so wait until the weather warms enough for them to emerge.

Once you’ve assessed your plants and decided what type of pruning each needs, you can create a personalized yearly timeline. I highly recommend keeping a gardening journal that becomes your own living almanac. Over time, it will serve as a thorough guide to your garden’s needs, with dates, seasons, and reminders mapped out—plus notes on what crops and flowers to look forward to as the seasons change.  It's a great gift to give to your future garden!