Gardeners, sharpen your clippers!
In the Valley, early February is an excellent time to prune nearly all woody shrubs and trees. Ideally, pruning is done immediately prior to the onset of a plant’s growth cycle. If a plant is pruned at the beginning or in the middle of a dormant period, it may go into a debilitating funk from which it will never recover.
Only last fall, in our neighborhood library’s landscape, sturdy shrubs such as India hawthorn (Rhapiolepsis indica) and mock orange (Pittosporum Tobira) were radically cut back. Several of these shrubs, although in good health at the time of pruning, have yet to show new growth and are probably dead.
India hawthorn and mock orange, like most of the shrubs in our gardens, are evergreen and reasonably drought tolerant. Being evergreen means that they are covered with leaves year around, even if they experience leaf fall on a continuous basis, a little at a time. Yet radical pruning can be a fatal shock to such a plant’s system, especially when done at the onset of dormancy.
While evergreens do not experience the deep dormancy of deciduous plants, evergreens undergo a period of semi-dormancy, sometimes called quiescence, when they put on new growth reluctantly, if at all. The small amount of growth exhibited by evergreens during their quiescent period may be suppressed by radical pruning which, in removing most of the plant’s leaves, eliminates the plant’s ability to photosynthesize and manufacture sugar, its source of energy and nutrition.
To be safe when pruning a shrub or tree, never remove more than one- third of the leaves in a single pruning. Unprofessional tree trimmers may remove up to 90 percent of a tree’s leaves and still the tree grows flushes of new shoots and leaves that appear to be the picture of health. Yet such rampant new growth on an overpruned tree has two liabilities: First, this new growth will be excessively succulent and nitrogen-rich, making it attractive to insect pests; second, the new growth will be structurally weak, developing into many attenuated, closely spaced, brittle branches having little wind resistance.
The only trees and shrubs you would not prune at this time of year are those that bloom in February, March or April. Most azaleas and camellias, for example, are either flowering now or will soon be in flower. Prune them as soon as they stop blooming.
When pruning back low-growing, mounding or herbaceous shrubs such as the many flowering sages (salvias), dusty millers, lavender santolinas, helichrysums, thymes and marguerite daisies, the age of the plant will determine the amount of pruning that may safely be done. Bear in mind that most of these popular shrubs will look good in the garden for three to five years before they will largely lose their aesthetic appeal.
–Norm Carney e-mailed as follows: “A gardening friend from Thailand ate an orange from my garden and said it was sour. He suggested sprinkling a little salt around the tree’s root zone as a way of sweetening the fruit. What do you think?”
I have never seen evidence that salt applied to the soil or, for that matter, any other cultural practice, can affect the taste of fruit on a tree. There is a widespread notion that the amount of water applied to the soil around a fruit tree affects the sweetness of the fruit, but this seems to be nothing more than an old wives’ tale. At the same time, it is true that certain varieties of fruit do not sweeten in certain climates. It is a fact, for instance, that many varieties of citrus grown in tropical Asia are sweeter than citrus grown in California. This probably has to do with the greater number of sunlight hours throughout the year – and proportionately greater photosynthesis and sugar production – associated with the tropics. Closer to home, varieties of grapefruit that are quite sweet when grown in the Arizona desert may taste rather bland when grown here in the Valley.
Gardeners, sharpen your clippers!