Watering Redwoods
By Jackie Woods UCCE Master Gardener
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
Sequoia sempervirens, also known as Coastal redwood or California redwood is a much beloved, magnificent evergreen with an average lifespan of 500-700 years (can live up to 2000 years) and can grow as tall as 360 feet. These 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.
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, thus creating stability for these tall beauties. They thrive in a moist environment and get approximately 40% of their water intake via coastal fog. The natural habitat for these trees receives 50-100 inches of rain annually, including fog, and neutral, well-draining soil. When planted in areas where rainfall falls below normal, trees will show signs of stress such as wilting or drooping leaves, brown leaves throughout and they'll shedding 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 18-24 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 3-4 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.