Northern California 1

BY JEFF COX / Kenwood, California, USDA Zone 9

Places to Visit

Take a world botanical tourin one place. The San Francisco Botanical Garden at Strybing Arboretum features 7,500 kinds of plants from all around the world, all growing on 55 acres of Golden Gate Park. There’s a world-class horticultural library there, too. Visit virtually at or physically at Ninth Avenue and Lincoln Way, San Francisco.

That Lucky Fog

Mark Twain famously said, “The coldest winter I ever spent was one summer in San Francisco.”

He made the quip because of the unique climate that makes the 500-mile stretch of coast from Big Sur in central California to southern Oregon a gardener’s paradise.

Here’s what happens: the water along this coast is a steady 50°F year-round. That’s far too cold for swimming or surfing without a wet suit. When warm air hits cold water, dense fog occurs. Just 30 to 50 miles inland, summer temperatures can reach well over 100 by mid-afternoon. Rising hot inland air pulls the coast’s cold fog through the Golden Gate and over the coastal hills, pouring it down the hillsides in torrents.

When I first moved to coastal California, I thought the fog was simply a nuisance. But as I began to garden in this climate, and became aware of the fog’s rhythms and consequences, my understanding of its benefits grew. The more I knew about it, the more I developed a great affection for this phenomenon.

Fog is mist, and I watched my ornamentals and vegetables respond to their natural nightly misting with brighter flower colors, thriftier growth, and that wordless joy that plants communicate when they are happy with their spot. Plants nearest the ocean, where fog is densest and wettest, explode with exuberant growth. Visit the seaside town of Mendocino some day—you’ll marvel at the gardens.

But happy plants marked just the beginning of my appreciation of the fog. On a purely personal level, I came to look forward, each hot summer day, to the fog’s natural air conditioning. It cooled the evenings so beautifully. And I discovered that this is one reason for the world-class wine grapes that grow in the belt where the fog encroaches on the land: Sonoma County, the Napa Valley, and regions to the north and south. A summer full of hot, sunny days creates the sugars and grape flavors that yeast converts into wine. Meanwhile, nights of cooling fog allow the development of the crisp acids that make great wines so food friendly.

And I learned that the region’s awesome redwood trees—the tallest trees on the planet—owe their existence to the fog. It seldom, if ever, rains in summer in the fog belt, but a friend told me that he placed a rain gauge under the canopy of a redwood forest in August and collected eight inches of precipitation. The voluminous needles of the redwood trees comb the fog, collecting the mist, combining it into droplets that fall and water these giant trees. The taller the tree, the more water it can collect and drop to its roots. That’s why redwood trees are so tall—some as tall as 40-story buildings. Redwood roots are very wide but very shallow, because that light “rain” under the canopy doesn’t penetrate far into the soil.

A map of redwood territory is nearly identical to a map showing where ocean fog spreads inland. Like those old trees, c I’ve learned to love it. H


Hokonechloa macro ‘Aureola’

Japanese forest grass (Hakonechloa macra Aureola’) grows to about 18 inches in pretty masses of gracefully arched bamboolike green leaves with gold stripes. Plant it with Alchemilla mollis and set a few pots of yellow-orange tulips among them for a bright spring show in the woodland garden. Sources, page 70.

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