Willow Glen, California Since 1992
Gardening
Trumpet vines are vigorous climbers on fences, trellises and trees. They are currently blooming with a profusion of orange-red flowers. Photograph by Shari Kaplan By Tony Tomeo Unlike most deciduous tree species that defoliate in autumn, Privet (the terrier) defoliates much of his coat prior to the warm weather of summer. I manage my beard in a similar manner, permitting it to return each October and removing it by April. I would prefer to wear the beard throughout the year but have found by wearing it two months late this year why beards should be used as annuals and why terriers are deciduous. Heat, low humidity, increased sun exposure and potentially dry soil associated with summer weather may be detrimental to many species. Protection from extremes may be necessary, just as protection from frost is necessary for a few species during winter. Each of these factors rarely cause problems alone, but may be very detrimental in conjunction with any of the others. Many species may be damaged by foliar or cambial scald if too exposed or if surrounded by reflective surfaces such as light-colored walls, pavement, roofs or windows. Understory species (those that would naturally grow under a foliar canopy of larger species) such as Japanese maples, rhododendrons and ferns are easily damaged by foliar scald. Similarly, species that exhibit thin bark that would be shaded in natural circumstances, such as cherries, apples and maples, may be damaged by cambial scald if stems are too exposed. Scald is more severe among specimens or parts of such specimens that have recently become more exposed than they have been previously. For example, a Japanese maple that had been grown within a partly shaded environment would be very susceptible to foliar scald if relocated into an exposed area. Likewise, cherry trees are very easily damaged by cambial scald if pruning exposes stems that would otherwise be shaded. Roots may be scalded or "cooked" within certain containers if too exposed. Black vinyl containers used for nursery production are not suitable for use in the garden unless contained within a larger container or otherwise shaded. If exposed, the black vinyl becomes very warm and transfers the heat directly to the root system, cooking roots in direct proximity. Most clay containers are well insulated, but can accumulate enough warmth to enhance proliferation of fungal rot organisms. Larger containers may be shaded by sprawling species that hang out over the edges of the containers if space allows. Irrigation must, of course, be modified to accommodate for warmer and dryer weather. Evapotranspiration (evaporation of moisture from foliar surfaces) is enhanced by heat and low humidity, particularly if air circulation is augmented by a breeze. Those of us who dry the laundry out on a line are perhaps more aware that the weather conditions more conducive to an expeditious "dry cycle" are less favorable for negligent irrigation. It is generally best to increase the duration, more than the frequency, of irrigation whenever possible. Frequent irrigation promotes root growth near the surface, where it is more susceptible to environmental discomforts. Irrigation that is both frequent and generous will also inhibit growth of deeper roots and may promote rot within larger root systems. Lawn, groundcovers and shallowly rooted species that require very frequent irrigation should not be so generously irrigated that lower strata containing root systems of more substantial species are constantly saturated. Desiccation of the soil surface between irrigation deprives fibrous surface roots of moisture necessary to replace that lost to evapotranspiration. This is why soil should be well-drained but exhibit adequate moisture retention. Mulching helps to insulate the surface of the soil as well as to retain some of the moisture that would otherwise evaporate. Flower of the Week: Blood-red trumpet vine Clusters of four-inch-long, trumpet-shaped flowers extend from the foliar mass of the blood-red trumpet vine, Distictis buccinatoria, during warm weather from late spring to early autumn - the same time frame in which terriers are somewhat defoliated. Sporadic floral clusters may also appear in winter if the weather is unseasonably warm. Flowers are typically orange-red with yellow throats; they later fade to slightly purplish-red. The pinnately compound, glossy leaves are typically composed of a mere pair of oblong leaflets approximately three inches in length. Young specimens respond appreciatively to regular irrigation and fertilization until established. Horticulturist Tony Tomeo can be contacted at 408-358-2574 or at LGHORTICULTURE@aol.com. |
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