In the garden, it's useful to know where any particular species originated from or how it is adapted to its particular lifestyle. With this information, the various preferences of each species may be accommodated more efficiently. For example, blue oaks will be happiest in a dry, rocky area outside of the irrigated garden.

Most species commonly available are well adapted to the climate and soil of the Santa Clara Valley. Those that are not so adapted are simply not marketed here. This is why weeping fig is grown as a houseplant, but is not available as landscape material here like it is in Los Angeles.

Of course, many more species can grow in the Santa Clara Valley than in most other climates of North America.

However, summers may occasionally be too cool for some or too warm and dry for others. Winters may likewise occasionally be too cool for some or too mild for others. For example, tropical hibiscus may be damaged by frost, but winter weather may not be cold enough to initiate spring bloom of some bulbs.

Many native species are better adapted to endemic climate and soil than any exotic species, but consequently cannot tolerate regular irrigation as well as exotic species because irrigation provides so much more moisture than seasonal rain.

Many species have adapted to more than merely endemic soil and climate, such as grazing wildlife or frequent fires. In fact, most native species are adapted to occasional brush fires by producing seed that is dispersed only as the parent plant succumbs to fire.

The Monterey pine is designed to burn hot and fast, to completely kill competing species, so that Monterey pine seedlings have an advantage as they emerge.

The California fan palm also eliminates the competition as it burns, but is designed to survive the fire. Both the giant sequoia and coast redwood are designed to be resistant to fire damage.

Tree of the Week: "Big tree" (giant sequoia)

Local arborist Michael Hart returned from Long Island to escape the snow and cold weather, but then promptly indulged in a road trip to snowy Sequoia National Park to visit the "big trees," Sequoiadendron giganteum, also known as giant sequoias. He sent this photograph of himself with the General Sherman Tree to his colleagues in New York. Older cities in the East may have larger urban trees, but the biggest tree, and in fact the largest species ever, is native to the western Sierra Nevada Mountains between Placer and Tulare counties.

Although shorter than the related coast redwood, General Sherman—the tallest of the big trees—is 275 feet tall, with a trunk diameter of 35 feet! The trunk does not taper much and has an estimated volume of approximately 52,500 cubit feet and weighs approximately 1,385 tons! Most garden enthusiasts will not likely be acquainted with any recently planted tree long enough to see it become as large. General Sherman has been growing for approximately 2,500 years.

The dense foliage is somewhat gray and prickly because it is composed of small foliar scales with sharp tips. Small branchlets are mostly covered with these overlapping scales. The reddish-brown cones are larger than those of the coast redwood, but are rare among young trees. Healthy trees may grow as much as 3 feet every year. Irrigation of established trees should be infrequent but generous, and soil should drain well.

This species actually prefers colder climates and is more popular in the Northwest than it is here in the Santa Clara Valley. In fact, Forest Grove in Oregon was named for its grove of big trees, which was planted by the original settler. The cultivar "Pendulum" cannot support its own trunk or stems, but can be staked and is an interesting oddity.

Horticulturist Tony Tomeo can be contacted at 408.358.2574 or at LGHORTICULTURE@aol.com.