When to prune what

Winter, and why it is the default

Late fall through late winter is the main pruning season for large hardwoods in the Piedmont, and there are four separate reasons for that, all of which point the same way.

The canopy is off, so the structure is visible. From the ground and from inside the tree you can see which limbs are crossing, which unions are tight, where the deadwood is, and how the weight is distributed. In August, none of that is visible from anywhere.

The tree is dormant, so it is not spending stored energy on new growth while it is being cut. Wound closure begins as soon as it wakes up in spring, which means the cut spends the shortest possible time open.

The ground is often firmer than it is in a wet spring, which matters when a bucket truck or a chipper has to cross a lawn. And insect activity is at its lowest, which reduces the chance of attracting anything to fresh wounds.

Practically, that covers oaks, maples, tulip poplar, sweetgum, hickory, elm, and essentially every large shade tree in a Winston-Salem yard.

Spring-flowering trees, after the flowers

Dogwood, redbud, flowering cherry, and other spring bloomers set the buds for next spring's flowers during the preceding summer. Prune them in winter and you cut off the flowers before they open. Prune them in the few weeks right after they finish blooming and you get a full season of growth to set new buds, so nothing is lost.

The same logic runs the other way for summer-flowering plants, which flower on the current year's growth and are therefore pruned in late winter before growth starts. Crape myrtle sits in that category, and it is also the species most routinely butchered in this region by being cut back to knuckled stubs every year. That is topping under another name, and it produces the same weakly attached regrowth on a smaller scale.

The spring flush, and why to stay out of it

There is a window in early to mid spring when a tree is pushing all of its stored energy into new leaves and shoots. Heavy pruning during that burst takes away the growth the tree has just spent its reserves producing, which is the worst possible timing from the tree's point of view. Light clearance work is fine. A major reduction is not.

Summer, and the drought question

Summer pruning is not forbidden and is sometimes the only practical option, particularly for clearance work that cannot wait. What to avoid is heavy pruning on a tree that is already under drought stress, which in a dry Piedmont August is a real consideration. A tree with browning leaf margins in late summer is either short of water or dealing with bacterial leaf scorch, and neither is a good moment to take a quarter of its canopy off.

One genuine advantage of summer work: defects are easier to spot on a tree in leaf when the problem is physiological rather than structural. Deadwood is obvious in July because it is the part with no leaves on it.

Jobs with no season

• Deadwood. It is already dead. Remove it whenever it is found.
• Hangers and broken limbs. After any storm, immediately. A limb lodged in a canopy is the most commonly overlooked hazard on a property.
• Anything over a walkway, drive, or roof that has become a genuine problem. Safety outranks physiology.
• Storm cleanup. Obviously.

How much to take at once

Less than most people expect. A healthy mature hardwood can generally handle losing a modest proportion of its live canopy in a single season. An older tree, a stressed tree, or one that has recently been through construction damage handles considerably less. Deadwood does not count against that budget, since it is no longer contributing anything.

A quote proposing to take half the crown off a mature oak is worth a conversation before the work rather than after, because that is not pruning, it is a slow-motion removal.

The one thing never worth doing

Topping. Cutting large limbs back to stubs, with no regard for where a lateral branch is, removes the leaf area a tree lives on and forces a dense flush of fast shoots from the cut ends. Those shoots attach to the outside of the stub rather than being integrated into the wood, so they are far weaker than the branches they replaced. Within a few years the tree is the same height with worse structure and a decaying stub in the middle of it. Every arboricultural organisation in the country says the same thing about it, and the reason it keeps happening is that it looks decisive. Reduction pruning, cutting back to a lateral branch big enough to take over as the new leader, achieves the actual goal without any of that.