Olive Trees – Varieties and Care

With so many Olive trees varieties available for sale in Australia we look at how to grow them

Olive trees are widely grown in Australia as a commercial crop for both fruit and olive oil. Olive trees make a great hardy tree for the home garden and many varieties can easily be grown in pots or containers.

Olives are traditionally from a Mediterranean climate, and they do perform well in these conditions. Basically dry warm to hot summers and wet winters. Olive trees do need a cold winter period to flower properly, as a guide a period of temperatures below 12C (53F), however, temperatures below 8C (46F)are not suitable.

In cold climates olive trees will still grow, however they will not produce good fruit and may need to be overwintered in a greenhouse.

How to grow Olive Trees – Basic Care

Olive Trees are perhaps the oldest cultivated tree in the world, with a history dating 100s of years to pre roman times.
These are a slow growing, long lived evergreen tree valued for their fruit and the olive oil produced from it. It is interesting to note that this is a tree that is now being used as an ornamental and as windbreaks, many vineyards now use olives as a boundary. Olive Trees were planted outside the Sydney Opera House some 50 years ago, they are still going strong.

Here’s a summary of how to care for olive trees so they thrive in a typical Australian garden (or suitably warm/ Mediterranean-style environment):

• Sunlight & Location: Plant in a spot with full sun — at least 6–8 hours direct light daily. Shelter young trees from strong winds if possible. 
• Soil: Use well-drained soil; olives do not like waterlogged ground. If soil tends to retain water, improve drainage (e.g. raised beds, sandy amendments). A neutral to slightly alkaline pH is often acceptable.
• Watering: Once established, olives are fairly drought-tolerant. However, during dry spells (especially summer) and during flowering and fruit-set, give deep, infrequent waterings rather than frequent shallow watering. Mulch around the base to retain moisture and suppress weeds.
• Fertilising: Before planting — mix in well-rotted manure or compost to enrich soil. Later on, a boost of fertiliser in spring helps support flowering & fruit set.
• Pruning: Light, regular pruning is best. Remove suckers at the base, downward-facing or crowded branches, and open up the canopy to promote air flow and light penetration. For fruit trees, prune after harvest rather than heavy pruning while fruiting. Avoid over-pruning, especially in older trees.
• Harvesting: Most olives are bitter straight from the tree — even when fully grown — so they need curing/pickling before eating. Depending on variety and intended use (table vs oil), you may pick at different stages (green → early, or fully dark for oil).
• Container planting (if limited space): Olives can be grown in pots — provided the pot is large with good drainage, and the tree receives enough sun and occasional watering. In pots, water needs are higher; in very cold or frost-prone zones, containers are more portable and easier to protect.

Pruning Olive Trees

For best fruit production, olive trees do need to be pruned, this is done from early on so that the tree grows into a form that is open, well shaped and easy to harvest.

1. First remove any suckers
2. Remove downward facing branches
3. Open the tree up so that fruit ripens more easily.
4. Try not to prune to hard with older trees.
5. Light regular pruning is best, so start early.

Olive trees prefer a cold winter and a hot dry summer, they do well in South Australia and Victoria. Olive trees need a well drained soil however they do appreciate watering during summer, soak once a month in dry periods, and fertilization will help promote growth. Olives prefer full sun and will grow well in pots. To promote increased fruit size olives can be ‘thinned’ on the tree. Olives are preserved by using salt, or a saline solution, olives ‘raw’ from the tree are bitter and inedible.

When planting out a young olive tree, dig in well rotted manure and remember to stake the plant, best time to plant is in autumn, although olive trees are hardy and can be planted throughout the year. If planting during warmer months remember to water on a regular basis.

Pests and Control Methods

Even though olives are relatively hardy, there are pests and diseases that commonly affect them — especially in wetter, humid, or coastal areas.

Common Pests & Diseases

• Scale insects — these can affect olives (and related trees), often appearing as small orange or pinkish dots beneath leaves. 
• Peacock spot (fungal disease) — causes blotches/sooty spots on leaves, often during wetter or cooler seasons. Leaves may blacken or drop. 
• Olive lace bug — an insect (native in Australia) that sucks sap from the underside of leaves; heavy infestation can defoliate the tree and even kill it.
• Olive fruit fly — can attack fruit, affecting yield and quality (particularly important for table-olive or oil production).
• Birds — once olives start ripening, birds may pick at fruit, reducing harvest.

Control Methods / Good Practices

• For scale insects: Regular inspection (especially underside of leaves). If found, treat with white-oil sprays or targeted insecticides that hinder reproduction.
• For fungal disease (Peacock spot): Spray with a copper-based fungicide (e.g. copper oxychloride) in late autumn (after harvest) to eliminate spores — repeat in early winter if necessary.
• For olive lace bug: Spray underside of leaves (e.g. with eco-oil or pyrethrum) when infestation appears.
• For fruit fly: Adopt integrated pest-management — encourage beneficial insects, maintain garden hygiene (remove fallen / rotting fruit), inspect fruit regularly; apply appropriate chemical or biological control if required.
• For bird predation: If harvesting for table olives or oil, consider netting or protective bird deterrents once fruit begins to ripen.

Harvesting Olives

Olives are an interesting fruit when it comes to harvest. As olives ripen and mature they change colour from green to black and can be harvested at a number of stages.

From fruit set in spring, until harvest can take 7 months.

Olives should be left on the tree until they reach full size.

• Green olives are the first stage and will be ready to pick when they give a creamy white juice if pressed or squeezed, they will still be firm. Green olives need to be cured before eating are often marinated. Eaten raw they are very bitter and inedible.
  
• Black olives are left on the tree until they turn s deep purple to black and usually marinated takes around 4 months after green olives are picked. Black olives are also cured before eating usually by lacing in a brine solution for from 3 months up to 2 years.

As olives ripen and darken they begin to produce the oil that is extracted by pressing

Best varieties for different Australian regions / climate zones 

Different cultivars of Olea europaea (olive) suit different climates / conditions, so your region can guide which variety to plant:

Different varieties of Olive Trees are recommended for producing Oil and For Eating (Table Varieties). Some, as marked with an * are regarded as multi purpose.

Olive Trees for Oil

Oil Trees for Table or eating

Where To Buy

BLERICK TREE FARM 
55 McDougal Rd Neerim South Victoria 3831 PH: (03) 56281507
Advanced ornamental trees and garden designs and concept plans. Direct to your property combined with specialist knowledge and outstanding service. 
www.blericktreefarm.com.au