The Midpeninsula's temperate weather serves as an ideal climate for all kinds of trees, natives and non-natives alike. But even in this moderate climate, temperatures do turn chillier in fall and winter, and when they do, that's the best time to take care of some routine maintenance to help trees stay healthy.
Deva Luna, a horticulturist and designer for Earthcare Landscaping, is teaching a pruning and propagating class for the city of Palo Alto on Nov. 23 offered through the Bay Area Water Supply and Conservation Agency. She will offer tips and tricks on how to properly maintain trees and how to make new plants from old (called propagation). In addition to helping homeowners learn how do it themselves, Luna also will talk about hiring an arborist and share with people how to tell if the arborist is doing a good job.
With this class, Luna aims to share her love for plants and teach others how to tend their gardens.
The right time to propagate varies from plant to plant, but for most perennials, fall is a good time because the weather is cooler and the plant shoots are firm, she said.
"First of all, it's fun working with plants and nature. Second, you can do it inexpensively and third, you would propagate when you have something special or unique you want to reproduce," Luna said.
Just as fall is a good time for new plants to take root, it's also an opportunity to prepare trees for the cold season and set them up for healthier growth in the spring. As trees begin to go dormant for the winter, pruning trees ahead of the storm season also prevents falling debris.
Luna said that pruning is useful in maintaining the landscape and functions as a way to control how things look.
"My theory is to try to make things look as natural as possible," Luna said.
She also said that without proper care, trees can cover windows, eaves and even go so far as to damage house foundations.
Luna said a good strategy is making choices early in a tree's life, noting the importance of shaping trees while keeping in mind how it will look in the future. In an ideal situation, a tree would need no pruning — best left alone — but for most people, pruning is a way to decrease the size of a tree. Taking a step back, it is just as important to plant the right tree for the given space as it is to maintain it.
"You shouldn't plant a redwood, the tallest tree in the world, near a powerline or too close to a house," Luna said.
Some trees need to be watered more often than others, or fertilized, or pruned. According to Luna, each tree is unique and should be researched to provide the best care.
"The very best thing for a tree is to understand what it needs," Luna said. "All trees are not the same and require different levels of attention."
Properly pruning any tree includes removing obvious problem areas, such as dead, diseased or broken branches, and making smart choices in where, how — and how much — you cut.
"It's important to properly treat trees," Leonardo Rivera, an arborist for over 11 years, said. "Otherwise you can jeopardize the structure of the tree and potentially (it will) fall over."
An arborist for over 11 years, Rivera is the district manager for the Davey Tree Expert Company in Menlo Park and assesses and maintains healthy trees in the Peninsula area.
"The best time to prune is before trees go dormant, between fall and winter," Rivera said. "Once the leaves fall, it's easier to assess the tree structure."
He said it is important to cut as little as possible, removing 20 to 25% of tree branches at most.
Focusing on the branches that need attention will prevent cutting too much, a common mistake.
"Think twice before every cut because once it's gone, its gone," Rivera said. "Think of how the tree will look with a cut and consider what other branches need to be pruned."
Remove branches that are poorly attached to the trunk. According to Rivera, branches with a strong attachment will have a ridge of raised bark where the branch meets the trunk, where branches that have weak attachments won't have that ridge and often grow at a sharp angle (due to bark growing into the area where the branch meets the trunk.)
Rivera suggested that homeowners consult a professional arborist if they're not comfortable pruning or do not have the proper tools, especially with mature trees and tall trees growing near power lines.
Tree topping, in which the top of a tree is cut off in an effort to control its size, is not a recommended practice. As Luna pointed out, tree topping can lead to health issues such as sun damage, nutrient stress, insect attacks and decay.
Luna also said there are aesthetic issues with tree topping: Improperly pruned trees are unattractive and don't look natural.
"Trees are a thing of beauty, of majesty, and should be properly treated," Luna said.
Tree care tips
Arborist Leonardo Rivera recommended three steps to help homeowners assess and care for their trees.
First, check the tree for signs of weak branches and disease, focusing on branch attachments, checking the foliage for insects (look for leaves that have been eaten), and looking for brown spots on the trunk, which could be a sign of fungal diseases.
Second, prune no more than 25% of the tree. In addition to dead or broken branches, remove any small, thin shoots on the branches (known as water sprouts) or that grow from the base of the trunk.
Rivera described a technique called the three-point cutting method. The first cut on a branch should be about 12 inches away from the trunk, on the underside of the branch, about a quarter of the way through. This is called an undercut, which prevents bark from peeling off and damaging the tree.
The second cut should be three to six inches away from the undercut and go all the way through the branch. The weight of the branch will cause it to snap where you made the undercut and fall away. Then make the last cut outside of the thickest part of the branch to remove the remaining stub and allow for proper healing.
"The last cut should not be flush, but still close to the trunk," Rivera said.
Third, fertilize the tree to provide it with enough nutrients to last through the winter, so it will have enough energy to put out healthy growth when spring arrives.
Luna's pruning class takes place Saturday, Nov. 23, from 9 a.m. to noon at Mitchell Park Library, 3700 Middlefield Road, Palo Alto. Register at bawsca.org/classes or call 650-349-3000 for more information.
If you'd like to learn more, call Davey Tree Care's Menlo Park office at 855-335-8307.