Whenever I hear a complaint about trees, I am reminded of our precarious relationship with them.
As part of our immediate environment, we demand that trees should be as close to us as is physically possible, but then we become terribly agitated when a tree branch brushes against our window and keeps us awake at night.
We insist on living in back-to-nature settings where brushfires are common, yet tearfully bemoan our fate when surrounding trees, acting as torches, set our houses ablaze.
We love the shade that trees provide, but then complain that these same trees are a messy nuisance because of their sticky flowers, sidewalk-staining fruit, or excessive pods or leaf litter, to say nothing of their allergenic pollen.
Whenever I am asked how often a certain type of tree should be pruned, I am tempted to say “never.” In their habitats or natural surroundings, trees are never pruned and they survive just fine. The most ancient sequoia trees are more than 2,000 years old and olive trees may live for more than 3,000 years, while certain bristlecone pines (Pinus longaeva) dwelling in the White Mountains of California above Death Valley have endured for more than four and a half millennia.
Whatever you say about pruning, it is both an invigorating and a debilitating procedure. Pruning is essential in orchard management because its primary purpose is to promote growth of vigorous shoots with lots of flower buds that will turn into fruit. Yet any procedure that artificially pushes new growth is debilitating, too. A peach tree that is never pruned will be healthier, long term, than a regularly pruned tree. Yet to maximize peach production, significant annual pruning is required.
Those shade and ornamental trees that surround our living and working spaces require regular pruning for one reason only: They are nearly always subjected to adverse growing conditions where they simply do not have enough room to reach their mature size. If you can find a tree that is perfectly suited to a particular site, you will never need to prune it. This means it will have enough room to grow to its mature dimensions without interference from nearby structures.
In an urban environment, we are clearly talking about a very limited number of trees, none of which grow more than 20 feet tall. Examples would include Japanese maple (Acer palmatum), western redbud (Cercis occidentalis), red birch (Betula occidentalis), palo verde (Parkinsonia spp.), Mediterranean fan palm (Chamaerops humilis), Chinese fringe tree (Chionanthus retusus), mayten (Maytenus boaria) and plumeria, as well as several magnolia cultivars such as ‘Little Gem.’
Trees native to dry Mediterranean climates like our own, such as those that are indigenous to Australia and South Africa, should not be watered during the summer. When summer watering is excessive, these trees are prone to breakage. Leaves soak up more water than they can comfortably hold, the trees become top heavy, and large limbs break off or the entire tree may split down the middle. During the summer, never park under a eucalyptus tree that is growing in a lawn. The daily irrigation needed to keep the lawn green could result in dropping eucalyptus branches.
Coral trees (Erythrina spp.) are more prone to breakage than any other tree genus that grows in Southern California. Where coral trees are concerned, not only must you abstain from summer watering, but you really should prune them once a year, as soon as their brilliant flowering display, in orange or scarlet, comes to an end. Mature coral trees that miss a single annual pruning are highly likely to split down to the base if their trunks, whereupon they must be removed.
Roberts, who lives in North Hollywood, sent photos of a cape honeysuckle (Tecoma capensis) and a cereus cactus. His honeysuckle not only serves as a delightful snack for hummingbirds, but does a wonderful job of erosion control as well. Cape honeysuckle is a stand-alone species since it would only smother plants in its vicinity. Do not incorporate it into a garden design, but rather make it into an impermeable flowering hedge or screen, or just let it ramble over a slope. It tops out at a height of around 8 feet and will die back in a frost but should recover the following spring. Its serrated leaves are an incredibly lush tropical green and the curved orange-red trumpets which are its flowers will be highly visible throughout summer and into fall. It becomes increasingly drought-tolerant as it matures.
Peruvian apple or apple cactus (Cereus peruvianus) is as trouble-free as cape honeysuckle. Native to South America and sometimes referred to as night-blooming cereus, the flowers of this blue, columnar cactus are fragrant and its fruit is edible. In recent years, Israel and other nations with arid climates and limited water supplies have begun growing apple cactus on a commercial scale and exporting its fruit.