Redwood Trees

by Denise Levine, U. C. Master Gardener

Anyone who has stood in the cool shade of a redwood grove, head thrown back to catch a glimpse of the tops of the fringed circle, knows the mystery and comfort these beautiful trees share with us. But how many of us have noticed the incredible wonder of what is at our feet in the redwood forest? Ferns grow out of fallen trees, and violets and iris peek quietly out of shady nooks.

Here in Napa County, even some of us in town are lucky enough to share our yards with redwood trees. Redwood Road boasts mature redwoods in backyards just a few blocks from the freeway. But for those who love to garden, redwoods pose special challenges.

Redwood trees have shallow, aggressive root systems that can raise havoc with house foundations, sidewalks or lawn. Almost anytime improvements compete with redwood tree roots, the roots will win.

In town, perhaps the kindest setting for a redwood tree is the middle of a lawn. Redwood trees will be happy with the regular watering the lawn gets, but will still need to be watered deeply once a week and perhaps more in extremely hot weather.

Many plants can't tolerate the deep shade under a redwood or can't compete with the tree's aggressive, shallow roots. Others dislike the acid soil that results from the thick mulch of redwood needles. So what will thrive? Here we can take a lesson from the forest.

In my college days, I tromped around the redwood forests of Northern California. Redwood sorrel that looked like a leprechaun's dream of four-leaf clovers gone mad covered the forest floor. Sword ferns and wild ginger poked through here and there, and my favorite little flower, nodding white trilliums, were the best reward for paying attention on my walks.

Redwood sorrel (Oxalis oregana), redwood violets (Viola sempervirens) or darling little wild strawberries are all native groundcovers that thrive in the moist humus of decomposing redwood needles. Western sword fern (Polystichum munitum), trilliums (Chloropetalum or T. ovatum) and bleeding heart (Dicentra formosa) can thrive in shade. Wild ginger, white fairy lantern, checkered lily, California fawn lily and pink star tulip are native bulbs and plants that grow under redwoods and lead me to wonder if perhaps Shakespeare composed A Midsummer Nights Dream deep in the magic of a redwood glade.

Shade gardening with natives brings a subtle palette of plants into the garden. But subtle does not mean dull, as anyone who has ever marveled at the intricate sophistication of a checkered lily can tell you.

Just remember that redwoods love moisture. While some locations provide enough fog and dew on summer mornings to keep a redwood happy, in warmer, dryer areas where they might be more stressed, you can string misters up the trees and through the grove to simulate the moist, cool conditions redwood trees crave.

Growing California Native Plants by Marjorie G Schmidt (University of California Press) has an extensive list of plants that share the same cultural requirements as redwoods. Schmidt also lists sources for Native California seeds, bulbs and plants.