Garden doctors: It’s pruning time in Sonoma County gardens

Q: Before I get out there and start pruning my shade trees, is there a difference in the way I should prune them, or should they be pruned in the same way? Any tips would be helpful. - Alan N. of Santa Rosa

A: Good question. You would do a little more pruning on a young shade tree than on a mature tree of the same kind.

First let’s start with pruning the young tree. Here are few pruning guidelines:

1. Cut back any limbs that extend beyond the natural shape (crown) of the tree. This may mean pruning it a few inches or a foot or more. Cut back to a side branch that is growing outwards.

2. Prune out any broken branches, any that criss-cross each other and those that are growing inwards towards the trunk.

3. If a competing branch is trying to outgrow the main (central) leader, prune it back to its origin. One central leader (central trunk) will be more structurally sound than two that compete with each other.

4. Remove any root suckers and sprouts coming from the base or from under the canopy.

Guidelines for pruning mature shade trees:

There’s a lot less pruning to do here because, when they were young, you did the necessary pruning to help them develop a nice framework.

1. Prune any branches that are rubbing against each other, leaving the one that is growing in the best direction and that will continue to maintain the tree’s natural shape.

2. Prune off dead or broken branches.

3. If necessary, for low growing branches that hit you in the head whenever you walk by or perhaps hit when you open the car door, prune them back to the point where you can still maintain the shape of the tree. If that’s not possible, prune them all the way back to the trunk.

4. Prune out any sprouts that grow vertically from the branches. These are usually called watersprouts and need to be removed. They will compete with the leader and have the potential to snap off in a strong wind. They also deter from the natural shape and beauty of the tree.

5. Prune out any suckers also growing from the base of the tree or around the base.

Be sure to use sharp, clean pruners to make clean cuts.

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Q: What does “chilling” mean in regards to fruit trees? - John R. of Santa Rosa

A: Chilling is a term used for the accumulated number of hours a particular variety of fruit tree (or bush) needs, below 45°F, to influence the bud break, fruit set and fruit development. The number of hours need not be continuous. Most varieties require between 200 and 1,000 chilling hours each winter to break their natural dormancy. Insufficient chilling due to mild winters may be the most limiting climatic factor for apples, apricots, cherries, nectarines and peaches.

Dana Lozano and Gwen Kilchherr are garden consultants. Send your gardening questions to pdgardendoctor@gmail.com. The Garden Doctors can answer questions only through their column, which appears twice a month in print and online at pressdemocrat.com.