Garden Detective

Will pruning stop falling branches?

Garden Detective: Coastal redwood trees naturally grow close together. That helps support branches, say tree experts. Thinning branches may actually do more harm than good.
Garden Detective: Coastal redwood trees naturally grow close together. That helps support branches, say tree experts. Thinning branches may actually do more harm than good. pkitagaki@sacbee.com

Experts tackle readers’ garden questions.

Q: During high winds, one large branch broke loose from way on top one of our redwood trees. The tree company who cleaned up the broken branch said we planted the trees too close together and the wind cannot get through and that is what causes the branches to break. They said we need to “ladder” the trees, that is to take out certain branches up and down the tree, which would give the wind room to blow through and not break any more branches. This will cost $300 per tree. Could you please advise us if this is necessary?

Betty Romeo, Fair Oaks

Sacramento County Master Gardener Catherine Barkett: “Laddering is not a recognized horticultural term and removing healthy branches of a tree to ‘thin it out’ is not recommended for redwoods,” said Pam Bone, landscape horticulturalist and former coordinator of the Sacramento Master Gardener Program. In fact, it might do more harm than good.

While some trees, including many fruit trees, benefit from frequent pruning, redwoods generally thrive without pruning. Of course, dead, broken or diseased branches on any tree should be removed. Occasionally, a healthy branch that is growing too close to power lines or a roof may need to be pruned. And redwoods do occasionally drop branches on their own. In fact, “they are very good at self-pruning,” Bone said.

Every time a living branch is cut on a tree, a wound remains. Fungi, bacteria and insects can enter that wound and jeopardize the health of the tree. Wounds are the starting point in a living tree for wood decay, and wound decay can cause structural problems.

Needles of the redwood contain chlorophyll, and branches are full of these needles. Photosynthesis, the process by which plants convert water and carbon dioxide into carbohydrates for fuel, occurs in the presence of light and chlorophyll. When limbs are removed, a lot of needles are lost where photosynthesis would have occurred.

In addition, removing too many healthy branches on a tree may cause the remaining limbs to break. Branches on a redwood support each other in the wind, notes arborist and certified forester Ray Moritz. When space is created between branches, the remaining branches may be pushed too far by a strong wind and therefore could snap.

For information on how and when to prune trees, visit the University of California (UC) Agriculture and Natural Resources website at cagardenweb.ucanr.edu.

In the case of a big pruning project, find information on hiring a certified arborist from the Sacramento Tree Foundation at www.sactree.com/hire.

Catherine Barkett is a UC Cooperative Extension Master Gardener for Sacramento County.

Garden questions?

Questions are answered by master gardeners at the UC Cooperative Extension services in Sacramento and Placer counties. Send questions to Garden Detective, P.O. Box 15779, Sacramento, CA 95852. Send email to h&g@sacbee.com. Please put “Garden Detective” in the subject field and include your postal address. To contact UC Extension directly, call:

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