The Dry Garden: Best time to prune trees? Not now
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If there’s a tough instruction to follow in spring, it’s to relax. Don’t trim your trees, hedges or shrubs. Don’t paint the house. Greet sunshine by sitting back. The lazier you are, the more likely you are to hear the telltale cheep-cheep-cheep of baby birds, because spring is the high point of bird nesting season.
I say “high point” because California has a long nesting season. Hummingbirds have been broody since January and will remain so for some time. Think of them when you tell your gardener to leave the hedges, camellias and hibiscuses alone. Bushtits, swallows, wrens, woodpeckers, phoebes and finches are either sitting on eggs or constructing nests. Think of them, then put off termite work, gutter repair and tree thinning. The best months for tree work are August through December.
There is no one place to look for nests. L.A.’s birds might make a home beneath our eaves, employ hollowed-out spaces in rotten wood, weave baskets in high boughs or suspend sock-like structures tightly among the leaves at the tips of dangling tree limbs. What most nests have in common is near invisibility. Given the heavy predation of eggs and chicks by squirrels and other predators, the ability to camouflage a nest can be key to survival.
The idea that we can keep pruning, if we’re careful, is wishful thinking. When arborists or tree trimmers tell you it’s OK to prune in April, May or June because they will keep an eye out for nests, the blunt translation is: “Forget the birds, give us the work.” Although rules exist that require tree workers to stop cutting when active nests are discovered, a nest revealed is a nest imperiled.
In short, only one valid excuse exists for spring or early summer pruning: a danger in which a potentially falling tree threatens life or property.
So that unpruned gardens do not become overgrown during nesting season, control the irrigation. It is no exaggeration to say that year-round sprinklers drive year-round saws here in Los Angeles. For trees and shrubs, water deeply and occasionally, say once a month, to avoid the stress of drought. If you are forcing new growth after a spring flush, it’s a safe bet that you are overwatering.
This may seem a long way to go to protect birds, but consider the benefits. No other animal does the kind of job that birds do controlling insects. No pesticide matches their safety for humans. If your hibiscus has whitefly, it’s probably because constant pruning keeps out the flocks of bushtits that would have devoured the insects. If unwelcome caterpillars are wreaking havoc on your vegetables, rethink letting the garden crews with buzz saws evict the finches that would otherwise have eaten the pests. If rats appear on your telephone wires at night, you don’t need poison. You need a hawk.
Years ago, in a bid to stop the routine destruction of nesting grounds in Southern California, the Los Angeles Audubon Society produced the Guide to Bird-Friendly Tree and Shrub Trimming and Removal. Online versions are available in Spanish and English.
It’s a worthy document. After digesting its import, if you still want to work in the garden in late spring and early summer, there’s plenty to do, such as creating and managing a vegetable garden or ground-level hardscaping. As you yank winter vegetables to make way for summer crops, the birds you will have spared may be your tomato’s best line of defense against cutworms. -- Emily Green
Green’s column on low-water gardening appears here on Fridays. For an easy way to follow reporting from her and others, join our Facebook page dedicated to gardening in the West.
Photo, top: Feeding time for hummingbird chicks. Credit: George Wilhelm / Los Angeles Times
Photo, bottom: Feeding time for vireo chicks. Credit: Ricardo DeAratanha / Los Angeles Times