After a shrub or small tree leafs out in spring, you may notice that the ends of some of the branches have died back. This can be the result of an unusually harsh winter, a lack of moisture, or of transplant shock if the plant has been moved recently. (In the case of the plant shown above, Styrax japonica ‘Carillon’, transplant shock was the culprit.) Although the dead growth is alarming, it doesn’t usually mean the death knell for your plant: if you carefully prune away the dead growth and remedy the conditions that produced it in the first place, all should be well. (If the problem continues, the cause may be a fungal or bacterial disease, in which case you should try to identify the pathogen through your cooperative extension service or a local botanical garden and take appropriate action.) Before you start, arm yourself with a pair of good, sharp secateurs and loppers. If any of the branches are thicker than an inch in diameter, you’ll need a pruning saw as well. If you have a choice, use bypass rather than anvil-type pruners— the latter tend to crush stems (which will then heal slowly and invite disease) rather than making a clean cut.
1. Trim back the dead growth.
Use secateurs to remove the smallest twigs, up to one-half inch in diameter. Cut back to healthy growth. Use loppers for branches between one-half and an inch in diameter. For even larger branches, use a pruning saw and cut back to the collar"-the swollen ridge of bark near the base of the branch. Do not cut the branch flush with the trunk, but do not leave an unsightly stub, either. If the plant’s growth is congested, you can also take the opportunity to do some cosmetic pruning to clarify its shape and open up the crown to light and air.
2. Keep the plant stress-free. When you’ve finished pruning. feed the plant lightly with a balanced granular fertilizer by scratching it into the soil around the trunk, and keep it well watered throughout the summer. If you suspect that the damage was caused by winter cold, you can protect the plant with burlap in late fall, but it might be easier simply to replace the plant with one better able to endure the winter lows in your area.