Los Gatos Weekly-Times | 0234

August 21, 2002 Los Gatos, California Since 1881

Photograph by Shari Kaplan

The most striking attribute of the smoke tree is the profusion of 'smoke' its flowers produce during bloom. Smoke trees commonly grow with multiple trunks.

Location is everything when selecting trees for planting

By Tony Tomeo

I was aware that the easement directly below the utility lines was not an appropriate location for the six Lombardy poplars I installed there many years ago. I only did so because I knew I could control them by annual pollarding at about the same height as the telephone lines. Unlike proper pollarding, which allows some of the growth of the previous season to remain, I would prune back to the same "knuckles" every year. This procedure would allow the wounds to compartmentalize (heal) rapidly as new growth emerged on the same knuckles in spring, protecting the main trunks from decay. I could then eventually cut the trees into firewood as adjacent trees crowded them.

I unfortunately did not consider the efficiency of the crews who come to perform line clearance pruning. By attending the most recent of these performances, I was able to instruct them not to remove the knuckles as they had done so often before. I could then dress the wounds by removing stubs from the knuckles the following winter. This year, however, the crews came later than scheduled and I was unable to attend when I received the phone call that the dreaded orange truck was out front. I would have gladly explained that I did not want the knuckles removed, but when I returned the call, the crew was gone—with the upper two-thirds of two of the trees and the upper half of the others, knuckles and all.

This is only one example of why "location is everything." Large trees are simply not appropriate for easements under utility lines. Likewise, trees that typically exhibit voracious roots are not appropriate near pavement. Crape myrtle and purple-leaf plum are just not proportionate to the interchange of highways 17 and 85. Poison oak should not be used as a formally sheared hedge around a cutting garden. The list goes on. However, every species has its place—except perhaps poison oak.

Trees or informal hedges for utility line easements should not grow so high that they will require regular pruning to maintain clearance. Because most easements are at the rear of urban gardens, most garden enthusiasts prefer evergreen species that will screen an unwanted view. This consideration is neglected more often than one would expect. Deciduous species are often selected for this application during summer, when they perform quite nicely, but may disappoint as they defoliate in autumn.

Conversely, trees intended to provide shade during the summer should, in most situations, do the opposite in winter. Deciduous shade trees are very useful for keeping homes and offices cooler during warm weather but allowing sunlight through to warm the same buildings after the trees have defoliated. Evergreen trees are just as effective at cooling but continue to block sunlight when it would be appreciated.

Trees, as well as all other species used in landscaping and gardening, should be proportionate to their respective sites. Many trees simply grow too large for small areas. However, "micro-trees" are not necessarily always appropriate to every situation either. Crape myrtle, purple-leaf plum and Australian willow have recently been used perhaps too much because they so rarely cause any problems. In my opinion, they are just too puny for midsized gardens until they are very mature.

I would rather compromise with something like a red oak and contend with the associated minor problems later if it would be more proportionate. I say "compromise" because I would actually prefer a silver maple, but am aware that it is more voracious, does not live as long and would consequently not be as appropriate.

Tree of the Week: Smoke tree

Smoke tree, Cotinus coggygria (also known as Rhus cotinus), is actually related to poison oak (Rhus diversiloba). It forms a low, compact tree with multiple trunks, and may eventually grow to about 20 feet tall and wide. The round, bluish leaflets of the pinnately compound leaves are about two inches wide and exhibit autumn colors of yellow or orange.

Pale lavender "smoke" appears among large clusters of elongated stems of abscising sterile flowers. Bloom is more impressive among slightly stressed specimens grown in inferior or rocky soil. Drainage must be excellent if irrigation is regular. Full sun exposure is preferred. The cultivar "Purpureus" exhibits darker smoke and purple foliage that fades to green through summer. "Royal Purple" is purple through summer.

Horticulturist Tony Tomeo can be contacted at 408-358-2574 or at LGHORTICULTURE@aol.com.