That certainly was an interesting internship, because each of the arborists, who happened to be from various regions, wanted to share his experience. Green days involved lessons on trees of Hawaii and Southern California, and trees of Central California were discussed on yellow days. Red days were reserved for English trees. Blue days were concerned with trees of coastal New England, but trees of Appalachian New England were discussed on orange days.

I enjoyed each of the colors, but orange days were my favorite and educated me about, among many other things, protection of trees from severe weather. Weather in the Santa Clara Valley is fortunately not as fierce as it is in Appalachia, but many species that happen to be popular here are sensitive to even the mildly cold winter weather. Of course, the best way to avoid frost damage is to limit selection of species to those that will tolerate local winter weather, but this can be a bit too restrictive for many garden enthusiasts.

Some tender or even tropical species may be adequately protected within the shelter of lanais or porches. Some may be grown in pots in "marginal" areas if moved to safer locations prior to frost. Greenhouses provide ideal protection, but a sunny area in a garage may be a convenient refuge for sensitive plants during the coldest winter weather.

Areas that are below eaves are usually safe enough for marginally tender species, because radiation of heat away from the plants is somewhat inhibited. Exterior walls, particularly those that are exposed to sunlight from the south or west, radiate very minor amounts of heat energy at night, but this likewise helps protect against freezing. Stucco seems to retain heat into the night better than wood siding, and of course, dark paint more efficiently absorbs heat energy. Walls that are not insulated unfortunately necessitate undue consumption of heating fuel, but more effectively share heat from within.

Sensitive plants that are too exposed will otherwise require the protection of those unsightly "tents" the neighbors complain about. These tents can be as simple as tarps draped over stakes that are arranged outside the dripline of the "victim" and are sufficiently high to suspend the tarp away from foliage. Larger tents will require the additional support of cross members or cords between the stakes or other sturdy features in the landscape. If something freezes, don't prune it! Removal of damaged foliage not only deprives the specimen of protection from later frost, but also stimulates premature foliar growth that will be even more susceptible to frost. Likewise, fertilizer applied late may stimulate fresh growth, which is not as resilient as foliage that naturally slows in late summer.

Tree of the Week: English yew

The various cultivars of English yew, Taxus baccata, were a common topic on my red days and are much more popular than the "straight species." The cultivars are more compact and densely foliated, but each exhibits distinctive structure; some also exhibit variation of foliar color. The straight species grows slowly but may eventually be as high as 30 feet with a low and broad, but perhaps relatively sparsely foliated, canopy.

English yew is a conifer, but does not bear cones. Female specimens instead produce small, red fruit that contain only one seed. This fruit and seed is toxic, so it should not be permitted to accumulate where puppies or toddlers might find it. Individual needles are approximately an inch long and dark green. English yew grows well in partial shade or full sun exposure, but foliage may burn if too exposed during warm weather.

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