Everlasting Redwoods

By Bill Klausing
Sonoma County Master Gardener

Sequoia sempervirens, one of the iconic state trees of California, has traveled quite a journey through history to arrive here in Sonoma County. The Latin translation for sempervirens is ‘everlasting’, and it remains one of the oldest tree species on the planet. Fossilized remains show that over five million years ago this tree existed on multiple continents. Today is it isolated here in the coastal Pacific fog belt of North America, from the southern boundary of Monterey County to just 15 miles north of the CA/OR border. Of the estimated 2.1 million acres of old growth forest that existed at the time of the arrival of European settlers to California, approximately 95% have been harvested for lumber. An old growth forest of Sequoia sempervirens contains the greatest concentration of biomass of any acreage on earth. Though a few specimens of this species are thought to be nearly 2000 years old, the average life span of the redwood is about 500 years. It is amazing that only about eight generations of trees have lived here in our current old growth redwood forests, as it is believed that it was only about 4,000 years ago that these giants established themselves on the west coast of North America. Sequoia sempervirens have always been very susceptible to climate change; as the planet has warmed in recent centuries, the natural occurrence of redwood forests has been shifting northward along the coast, following the cooler coastal fog belt. It seems, though, that the topography in Oregon has prevented their further migration northward.

Sequoia sempervirens has developed quite an intimate relationship with the moist coastal fog of summertime and its associated drip. In fact, the presence of fog is much more important to the existing redwood forests than the actual annual rainfall. This fog allows the soil to remain moist during the dry summer months, and the increased humidity significantly decreases the water loss from transpiration of the tree and accordingly, its water demands are greatly decreased. There are 41 documented redwoods greater than 300 ‘ tall; one of those is located here in Sonoma County’s Armstrong Woods. Several more can be viewed in Montgomery Woods just west of Ukiah. In such tall trees a secondary ecosystem evolves high in the canopy; the details of this ecosystem are just beginning to be understood. Sequoia semperivens is a dominating tree, providing deep shade and limited opportunity for growth on the forest floor. Here in Sonoma County, the undergrowth of a redwood grove may include the following trees: Douglas fir, tan oak, California bay and Pacific madrone. A carpet of ferns, sorrel, and trillium also often blankets the soil. This biomass and its resultant decay is very important as the rich alluvial soils cannot provide all of the nutrients needed for the redwoods survival.

After learning the history and cultural requirements of this coastal icon, I am always given a moment of pause when I see 5’ tall Sequoia sempervirens in five gallon containers for sale by the dozens at one of the local big box stores. It is the rare homeowner, indeed, who has the space for what this small specimen will become in relatively short order. And there is an even smaller likelihood that the purchaser can provide the ecosystem that these trees crave and need to flourish: within an entire grove of its kind, located in the fog belt! So, small suburban lots are not the landscape of choice for this ancient giant. You can see what happened to the redwood pictured here. It clearly has been there for a number of years, but keeps getting lopped at the top because of its location under utility wires.

Even most commercial plantings of S. sempervirens in Sonoma County have been ill placed. They are either planted with little regard to their size even 10 years out or planted in parts of the County that are too hot and dry in summer. The cruelest treatment meted out to these beauties is along 101 between Santa Rosa and Petaluma. One has only to drive along that stretch and see the struggling specimens along the highway, barely surviving, to understand that they are left with not a shred of the majesty they deserve.

If you are interested in learning more about our coastal redwood, Humboldt State has a great website with many links for further information, including nonprofit organizations working tirelessly to protect the natural environs of Sequoia sempervirens.

Should you want an evergreen conifer of your own, there are many better choices for the home landscape. If you have your heart set on a redwood, you might try Metasequoia glyptostroboides, or dawn redwood. This cousin of S. sempervirens, though still a very large tree, does not have the same oversized qualities. The Metasequoia is native to China, is deciduous, and culturally mimics a bald cypress. There are varieties, such as ‘Miss Grace’, that are dwarf forms and are quite lovely and graceful. There are also any number of dwarf spruce, fir or pine varieties that grow to only 30-40’ tall at maturity, and can exist more happily in hotter summer weather. All evergreen conifers will need some supplemental summer water here in Sonoma County; although once established and if well mulched they are not water hogs. So leave the redwoods to the forests and visit them there to see them as they are intended to grow. As the TV advertisement says ‘don’t try this at home!

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