Olea europaea ‘Swan Hill’
From the Mediterranean. Along with palms, citrus, and eucalyptus, olives are regional trademarks along avenues and in gardens of California and southern Arizona. The trees’ beauty has been appreciated in those areas since they were introduced to mission gardens for the oil their fruit produces.
Willowlike foliage is a soft gray-green that goes well with most colors. Smooth gray trunks and branches become gnarled and picturesque in age. Trees grow slowly, typically to 25–30 ft. high and as wide; however, young ones put on height (if not substance) fairly fast.
Begin training early. For a single trunk, prune out or shorten side branches below the point where you want branching to begin; cut off basal suckers. For multiple trunks, stake lower branches or basal suckers to continue growth at desired angles. Large old trees can (with reasonable care) be boxed and transplanted with near certainty of survival.
Olive trees look best when grown in deep, rich soil, but they will also grow in shallow, alkaline, or stony soil and with little fertilizer. They thrive in areas with hot, dry summers but also perform adequately in coastal areas. They take temperatures down to 15°F/–9°C.
Olives withstand heavy pruning. Thinning each year shows off branch pattern and eliminates some flowering/fruiting wood, reducing the fruit crop—which can be a nuisance in ornamental plantings.
On fruiting varieties, olives ripen and drop late in the year. Without processing, the olives are inedible, and they can stain paving and harm lawns if not removed. In addition to pruning, reduce crop by spraying with fruit-control hormones when tiny white flowers appear. Or spread a tarpaulin at dropping time, knock off all fruit, and dispose of it. So-called fruitless varieties are not always reliably barren.
Leaves are deep green. Bears little or no pollen—a boon to allergy sufferers—and no fruit. Grows to 25 ft. high and wide.
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