Learning to tell is useful to you as a gardener because it extends your work season. Spring and summer are the book-listed best times to prune most plants, but these seasons are also busy with other work. Anything you can do on a comfortable day in winter, like pruning for structure or removing bad wood, gives you that much more time to do other jobs. Here are a few ways to tell if a particular branch is alive or dead. At first, you might find you need to go up for a close examination, but over time you’ll start to get a sense, even from a distance, that a section of wood on your plant doesn’t look right, and is probably dead.
Easily Spottable Signs
The first thing to learn to do is how you can tell dead wood at a distance, as you walk through your garden. These signs will let you assess the situation for follow-up work without spending a lot of time on telling for sure.
Leafless while other branches have green leaves. This is pretty obvious and is a quick and easy sign of death in spring and summer. Clinging dead leaves while other branches are bare. If your plant is deciduous it should be dropping its leaves in fall. Dead branches will not drop their leaves when they should; instead, the leaves will often hang on for months into the winter. Sometimes the fat blade of the leaf will be ripped off by winter wind, but the leaf stem will keep sticking to its node. These are all signs that the branch has died. Be careful, though: these are not good signs of death on oaks, beeches, and any sapling tree, all of which can normally hold leaves late. Bark has mostly fallen off, exposing smooth wood underneath. Old bark will naturally fall off a branch over time, but on healthy wood, this is replaced by new layers of bark. If on an old branch you see large areas of smooth wood, it’s a warning sign. Large fungus. If you have shelf fungus, wood conchs, or other kinds visibly infecting a section of wood, chances are that everything from that point and upwards along the branch is dead or at least weak and dying fast. Fungus in combination with other signs helps you be sure.
Checking to Be Sure
In cases of doubt, it is best to get up close to the branch and perform one or more simple, but decisive tests before you cut, especially if the branch is a major one that you’d like to keep if it’s alive. In cases where you can’t get close, such as a high branch in a tree, you might have to use binoculars or a pole saw to help you.
Scrape lightly and look for green. Just beneath the outer layer of every branch and twig is the cambium, a thin green layer. It is green in every season, even winter, but it turns brown when the plant dies. This is the most decisive way to test young wood, with an outer layer thin enough for you to scratch with pruners, a knife, or your fingernail on the youngest wood. On old branches with thick bark, you may need to slowly use a saw or another method of checking the wood.Shake the branch. A slender (roughly under a half inch in diameter) living branch should be flexible, bendable without cracking. Dead wood will snap. It will also often feel lighter, drier and hollower. Walking past shrubs with gloves shaking suspicious branches is a great way to quickly find dead wood.Look for buds. Early spring when the buds begin to swell and break is a great time for this sign. If a node on the branch contains even one firm or swelling bud, the branch is still alive. If all the nodes are bare of buds or have only dry buds that collapse when squeezed between your fingers, the branch is dead.Look at the branch collar. The branch collar is the ring that completely encircles the base of a branch, just above where it attaches to its parent branch or the trunk. The collar will usually be slightly raised or swollen looking. When the branch dies, the collar at its base begins, year by year, trying to engulf and swallow the dead branch. If you see a roll of wood that seems to be creeping up your branch, that branch has probably been dead a while and should be cut off just above the collar.
