Gardening: Growing Olives
Backyard olivista
The Western Cape’s Mediterranean-type climate is ideal for olive trees. Here’s how to grow your own. By Marion Whitehead
The evergreen olive has long been known as first among trees for the superior oil is fruits yield. The ancient Greeks smothered delicious dishes of Mediterranean vegetables in it, and used it in religious ceremonies. Today the rest of the world has caught on to the benefits of this healthy oil and connoisseurs of cold-pressed extra virgin olive oil talk about notes of flavours in much the same way as wine cognoscentis swirling a glass of their favourite tipple.
Choosing the right cultivar depends on what you want to do with it, says Carlo Costa, ARC-Infruitec’s senior horticultural researcher at Stellenbosch who wrote the handbook for olive growers. Most home gardens have space for no more than a couple of these large trees, so will be growing table olives by default. In South Africa, the most popular black table olives are Mission and Kalamata, while Manzanilla is preferred for green. Plant a Frantoio with them as it’s the most versatile cross-pollinator (most cultivars are self-sterile).
If you want to make your own olive oil, you’ll need space for 10 – 20 trees, planted four to five metres apart, to produce a minimum of 100kg of olives to take to one of the smaller mills. Frantoio is one of the top performing oil cultivars, says Carlo, who has a soft spot for this Italian variety as his grandfather selected for its oil and disease resistance in the early days of olive cultivation in South Africa.
When buying trees from a nursery, check that they are healthy and free of infestation of olive leaf spot, anthracnose, scale, tingid or any other pest, advises SA Olive, the industry association.
Olives are happiest in stony soils with a high gravel content – if drainage is not good, the tree will be prone to root diseases, so heavy clay soils are not suitable. Bob Hobson, farm manager at Morgenster, the estate that consistently wins international awards for its olive oil, recommends a pH of between 5.5 and 7 maximum. “Add agricultural lime if need be,” he advises.
Planting: Prepare a good one cubic metre hole as you would for any fruit tree, adding rock phosphate and compost. Volcanic rock dust or Talborne Organics’ Vita Grow are good multi-mineral boosters.
Protect the trunk from sunburn and rodents with a carton-foil tube and stake it loosely with twine to avoid wind damage.
Watering: Give young trees 15 to 20 litres of water a week during the first growing season. “It’s a myth olives don’t need water,” says Bob. “Once established, they can get by with very little water, but produce much better when irrigated regularly.”
Pruning: For the first few years, snip out only those branches which are in the way of others, or growing too near the ground. After that, select branches to form a semi-open vase shape, or go for a single main leader which is trained upright, with lateral branching encouraged so that a conical shape is achieved. “Don’t let the tree get too dense,” advises Carlo. “Keep it growing actively by pruning a bit every year.”
Pests: Our healthy climate is the main deterrent, but watch out for olive leaf spot in warm and moist conditions, warns Carlo. This fungal disease causes sooty spots and yellowing of leaves, later resulting in leaf drop and death of shoots. Spray in spring and autumn with a copper hydroxide fungicide that is safe for the environment, he advises.
Harvesting: Pick table olives by hand, making sure they are not damaged. Green table olives are made from unripe fruits, and are picked at the stage when they are a good size and have turned from bright green to yellow-green and begin to show a light pink blush. Black are made from ripe fruits which have turned completely black, but before they become overripe and soften. Olives are preserved in a salt brine after soaking to remove the bitterness and then normally undergo a slow fermentation process.
Oil olives can be stripped off the trees onto nets on the ground when most of the fruit on the tree is ripe. The oil content rises with colouring as fruit ripens, then remains relatively constant. Don’t delay harvesting or you’ll get lower oil quality. “Press within 12 hours on a cool day, or the fruit will oxidise,” advises Bob.
Olives bear biennially ie. a plentiful harvest one year is followed by a poor one the next. This can be offset somewhat by good feeding and watering, but don’t be surprised if your trees bear like crazy one year and act like lazy laggards the next.
For an olive processing recipe, see www.saolive.co.za.
This article first appeared in Landscape, Design & Garden
Olive cultivars
Mission
Hardy and adaptable, it originated in Spain and was taken to America by missionaries, hence its name. It’s good for black table olives and yields a fruity, peppery and slightly bitter oil with a thick, velvety texture and an almond aftertaste.
Kalamata
Greece’s principal table olive thanks to its size and fleshiness, it also yields good quality oil. Ideal as a black table olive, the tree is less adaptable than Mission.
Manzanilla
This Spanish cultivar is especially suited to green table olive production, has a low oil content and softens on ripening.
Frantoio
Originally from Italy, it is self-fertile and is used as a cross-pollinator for other cultivars, and produces high quality olive oil.