Growing Olives in Southeast Queensland

Growing olives trees for fruit production in southeast Queensland can be a challenge but with a good understanding of the trees cultural requirements and careful variety selection quality yields can be obtained.

Throughout the world, the major olive growing regions are almost exclusively found in Mediterranean type climates that are characterised by a winter rainfall pattern, mild winter temperatures and hot dry summers. A Mediterranean climate is one that resembles those of the lands bordering the Mediterranean Sea. These climates generally occur on the western coasts of continental landmasses, roughly between the latitudes of 30° and 45° north and south of the equator.

In southeast Queensland we have a subtropical climate of warm winters with a summer rainfall pattern and high summer humidity. Although distinctly different to the Mediterranean climatic, as long as some basic requirements are met such as good soil drainage and adequate pest management, olive trees will generally grow well in region. Fruit yield, however, can be inconsistent unless a suitable variety is selected and steps are taken to manage the flowering and fruit set processes.

Variety selection

Some winter chilling is required for flower initiation. In general, growing many of the traditional olive varieties in areas that rarely frost during winter can be a fruitless exercise as there may not be enough winter chilling for the flower initiation processes to take place. Some of the more recently introduced varieties into Australia, however, are more adaptable to warmer climates and will fruit well under the prevailing conditions.

Arbequina Varieties which have shown to be the more consistent in their bearing habits in warmer climates include: Arbequina, Manzanillo Arecuzzo and Koroneiki.  Of these, Arbequina would be the standout as the most reliable bearer in warm climates. It is self-pollinating and bears when it is very young.  In a warm winter variety trial in southeast QLD, Arbequina produced an remarkable average yield of 18kg per tree after 3 yrs.

We suggest that growers who intend to plant olives in a warm climate, outside of the traditional climatic zones should regard the initial planting as a trial and not a commercial venture until varietal performance is proven.

Cross-pollination
Although most olive varieties are self-fertile to some extent, research has shown that cross-pollination improves the fruit set of most varieties especially when the environment conditions are not optimal.  Generally having two or three different varieties growing in close proximity (30m) will facilitate adequate cross-pollination.  Arbequina, Arecuzzo and Manzanillo are some of the main varieties used for cross-pollination in QLD. If a tree flowers well in the spring and does not set any fruit it may be good indication that cross-pollination is required.

Soil Moisture and Irrigation
Adequate soil moisture throughout winter and spring is essential to ensure good flowering and fruit set. In olive trees, the process of flower initiation and development starts in late autumn and continues through the winter. Under winter drought conditions, this process is disrupted, resulting in either poor flowering or an excess of malfunctioning flowers that prematurely drop without setting fruit.

If rainfall is inadequate, it critical that supplementary irrigation is applied throughout winter and spring. Conserving soil moisture by spreading mulch and managing grass and weeds around the trees is also important. Young olives trees are poor competitors. Weeds and grass in the root zone of the tree will stunt growth and out-compete the tree for water and nutrients.

Nutrition
Adequate levels of nutrients especially nitrogen and boron are required for optimal flowering and fruit set. A leaf analysis taken in mid summer will give a good indication of the trees nutritional status and fertiliser requirements. Generally olives require either manure or other fertiliser on an annual basis for good fruit set. Splitting fertiliser applications throughout spring (60%) summer (30%) and autumn (10%) is recommended for granular NPK fertilisers. Manure is best applied as mulch once a year in late summer or autumn. The benefits of applying fertiliser will be limited unless there is adequate soil moisture for nutrient uptake by the tree.

Applying boron and calcium to the trees as a foliar spray before bud burst will help to meets the trees requirements of these nutrients and can improve pollination and fruit set.

Keep in mind that although the olive is a hardy and adaptable tree with the ability to withstand harsh summers, severe drought and poor soils, without adequate cultural care tree performance and fruit yield will be poor.  Neglected  trees, however, can be rejuvenated and brought into production with severe pruning and ongoing management practices.

Comments 22

  1. Your page is very helpful thank you , But it does not tell me the time of the year the fruit is good to pick in south queensland ; Sunshine coast region Ex: April , May or later Winter month for exemple ?.
    thank you Ch

    1. Post
      Author

      Olives in South East Queensland start to reach black ripening around late Feb/ March depending on the variety. Harvest for green ripe olives is usually around a month earlier. A general rule of thumb is once a few of the green olives on the tree start to get a purplish blush the olives are ready to pick for green olive pickling. For black ripe, pickling it is best to wait until most of the olives have starting to turn black but don’t leave it too long as they can start to get a bit soft and drop of the tree.

  2. your site is very helpful, just wondering if you know what cultivar the Helena variety is from that I have seen in a few nurseries?
    I have 1 peciul, 3x Helenas and another 4 which I think are different varieties. when purchased they just had olive tree on the tag- no variety written on it.
    thanks,
    JB

    1. Post
      Author

      Hi Jennifer,
      We found in our olive variety trial where we compared the performance of 70 varieties of olives that the selection we collected from St Helena island was identical to the Italian variety Frantoio.

    1. Post
      Author

      Hi John,
      Generally, mid-season varieties will be ready to harvest in Brisbane in March. Early season varieties may be Feb. If harvesting green ripe, harvest time would be a few weeks earlier.

  3. I’ve got several olive trees on Macleay island. They are very tall and overgrown and I want to prune them to reduce height and produce more olives.
    Can I safely prune the trees in January or should I wait till the cooler weather? What is the best month to prune?

    1. Post
      Author

      Hi Dave,
      Olive trees can be pruned any time of the year but there is a high risk of trunk sunburn if mature trees are pruned back hard in summer. Sunburn can be prevented by painting the trees with white wash,… see our blog on sunburn in olives . In general the best time to prune olives trees back hard is in Autumn or Winter.

    1. Post
      Author
  4. Great site. I have a tough spot in a western facing position where I need a tree I can keep to 4m . It must have a single trunk and be evergreen. As I already grow a large number of fruit trees on my suburban block (orange, mandarin, lime, custard apple, jaboticabi, guava, cherry guava) I am wondering if I could grow an olive, or if I will live to curse myself? The comments suggest St Helena grow huge here in Brisbane. Is there another cultivar that would be better for me in terms of height? Alison

    1. Post
      Author

      Hi Alison,
      If left unpruned most olive varieties will grow to around 6 to 9 metres tall with a spread of around 5m. In olive groves and backyards, however, trees are usually kept to a height of around 3.5 to 4.5m with annual pruning. This makes the trees easier to manage and means you don’t have to use a ladder when harvesting.

      With regular pruning the tree would not get too tall but olive trees can also be cut back very hard if you want to rejuvenate a tree that was allowed to get too big.

      St Helena is derived from the Italian variety Frantoio and it is a vigorous fast growing variety in warm climates. For a smaller growing tree with less vigour I would plant Arbequina or Manzanillo

    1. Post
      Author

      Hi Jasmine,
      The main characteristics used to identify olive varieties are leaf size/shape, fruit size/shape and seed shape. Visit the Australis Plants website to see images of most of the olive varieties grown in Australia

  5. What variety of Olive tree grows the largest fruit ? I live in Tweed Heads QLD/NSW border
    Thank you Gabby

    1. Post
      Author

      Hi Gabby,
      The olive variety that produces the largest fruit is the Italian variety Oliva di Cerignola (Bella di Cerignola). However, it is known in Australia mainly as “Jumbo Kalamata”….it is not related to the Greek Kalamata variety. The fruit is very impressive and weighs around 12-15 grams. The trees are very difficult to propagate making them hard to find in nurseries.

      Other large fruiting olive varieties suitable for Tweed Heads include Californian Queen( UC13A6), Barouni, Hojiblanco, Kolossus Kalamata and Manzanillo.

  6. I have a few olive trees should I cut all the thick branches going up the centre to keep them under control or would I loose too many olives

    1. Post
      Author

      Hi Steve,
      Productive olive trees are best kept to a height of around 3-5m. This makes it easier to harvest the fruit and manage any pest and diseases. Removing the upright centre branches is the best way to reduce the height of the tree and it is an essential practice in commercial olive groves. It is best if you prune the vertical branch at its base where it joins the main trunk rather than just pruning flat across the top of the canopy….this will prevent unwanted regrowth occurring at the top of the tree. Although some olives are produced on the vertical branches, the bulk of the olives are produced on the periphery of the canopy on the end third of horizontal branches. Rather than reducing yield, you will find in the long term that yield will increase as the tree’s energy will be transferred to the more productive horizontal branches. Some growers combine height pruning with harvesting by removing the tall vertical branches at harvest time and picking the fruit from the branches on the ground.

      Cheers

      Dr Greg O’Sullivan

  7. I live in Brisbane and would like to start growing an olive tree(s), however the soil on my block is poor. Very rocky.
    Which soil type do Olives prefer?

    1. Post
      Author

      Olive trees prefer well-drained, fertile soils with a neutral to alkaline pH around 7-8. They will survive exceptionally well in poor, shallow, low nutrient soils but growth will be limited. It is best to improve poor soils by adding manure, lime and compost. If the topsoil is shallow or poorly drained build a mound by importing quality sandy loam soil, add manure and lime and plant the tree on the mound.

      Cheers
      Dr Greg O’Sullivan

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