Q: I love the look of redwood trees and would like to plant a few in my landscape. How much water do they really need?
Caralyn D., Paso Robles
A: Sequoia sempervirens, also known as coastal redwood or California redwood, is a much beloved, magnificent evergreen with an average lifespan of 500 to 700 years (it can live up to 2,000 years). It can grow up to 360 feet tall.
The trees are native to the California Coastal fog belt and the southwestern corner of coastal Oregon. Sempervirens are not drought tolerant; they easily show signs of stress when deprived of water. Simply put, these trees need moisture — and lots of it.
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Coastal redwoods have a root system consisting of shallow, wide-spreading lateral roots. In a forest of redwoods, the shallow roots intertwine with those of other redwoods, creating stability for these tall beauties.
They thrive in a moist environment and get about 40 percent of their water intake from coastal fog. The natural habitat for these trees receives 50 to 100 inches of rain annually, including fog, and well-draining soil.
When planted in areas where rainfall falls below normal, trees will show signs of stress such as wilting, drooping or brown leaves. They’ll also shed more leaves than normal. When trees are stressed, they become more susceptible to disease and insect infestation.
So how much moisture do they really need?
A good rule of thumb is to water long enough to reach a depth of 18 to 24 inches. Use a soaker hose or sprinklers at or around the drip line of the tree (outer edge of the branches) as this is where water uptake occurs.
For large established trees, water every 3 to 4 weeks in summer — more frequently during record high temperatures. Your redwood will tell you whether or not you’re watering enough. If it’s healthy and thriving, you’re doing a great job. Applying mulch out to the drip line will help retain moisture.
If you decide redwoods are not the tree for your drought-tolerant landscape, don’t be discouraged!
Digger pines, also known as gray pine or Pinus sabiniana and Tecate cypress (Cupressus forbesii) are two beautiful, drought-tolerant, evergreen alternatives.
Jackie Woods is a UCCE Master Gardener.
Got a gardening question?
In San Luis Obispo call 781-5939, Arroyo Grande, 473-7190 and Templeton, 434-4105. Visit us at http://ucanr.org/sites/mgslo/ or email us at firstname.lastname@example.org. Follow us on Instagram at slo_mgs and like us on Facebook. Informative garden workshops are held the third Saturday of every month, 10 a.m. to noon at 2156 Sierra Way, San Luis Obispo. Garden docents are available after the workshop until 1 p.m. To request a tour of the garden, call 781-5939.