Growing Olives

Latest Update 4th March 2017.

Olive Tree
  • Olive trees grow well in Melbourne's climate with its hot dry summers, much like those parts of Africa and the Mediterranean basin where they originated.
  • They are long lived with some examples still growing after many hundreds of years.  They are small trees even when fully grown (8-15 metres) but respond well to careful pruning to control their size.    
  • Olive oil is our preferred culinary oil, but I don't grow enough olives on our single tree to make it ourselves.  We buy extra virgin olive oil for its health benefits and great flavour instead.  We do harvest green olives and cure them in brine to be used on salads and in snacks.
  • The tree is comfortable living in one of my drip irrigated fruit and herb beds, but the rich fertile soil is not ideal for olive production.  Although fruit quality is good, I suspect our harvest will always be modest.
  • My olive tree has been free from pests so far (about 5 years) and is easy to grow requiring no more than a light pruning once a year and monthly foliar sprays of aerated compost tea.  The whole bed in which it is grown is kept fertile with an annual top dressing of thermal compost. 
Details.
  • Binomial Name:                                       Olea europaea.
  • Family Group:                                          Oleaceae.
  • Variety                                                     Frantoio ???
  • Garden bed type:                                      Drip line irrigated bed.
  • Recommended soil pH:                             7.0 - 8.0.
  • Plant Spacings (centres):                          3000mm.
  • Good Companions:                                   Citrus, Rosemary, Tansy, Lavender.
  • Climate:                                                   Warm Temperate.
  • Geographic Hemisphere:                           Southern. 
Nutrition.
Growing Conditions.
  • Prefers hot dry conditions once established. 
  • Minimise soil disturbances to maintain a natural soil structure. 
  • Do not allow the soil to dry out completely.
  • Do not allow the soil to get too wet in winter.  You need free draining soil to grow Olives.
Feed the Soil 
  • In September each year remove old mulch, dead leaves and fallen branches from the soil surrounding your Olive tree.  Dispose of them in your compost heap. 
  • Apply a 60mm top dressing of thermal compost and cover it with fresh straw mulch.
  • Keep the mulch clear of the tree's trunk to prevent collar rot.
Growing Instructions
  • Spray the tree's foliage with aerated compost tea every month.
  • Lightly prune olive trees after harvest in autumn.  Trim back current years growth by half and keep the top centre of the plant open to let in as much light as possible.  This encourages the tree to fruit well every year and keep the fruit within easy reach for harvesting.
  • Remove any diseased or damaged branches.
Harvesting and Storage
  • Pick olives when they are ripe in Autumn.  I usually pick the whole crop when the last of them have started to change colour from green to black.
  • To cure olives and remove the bitter flavour, follow these instructions.
  • Make up some brine using 1/4 cup of salt to each litre of water.
  • Cut a deep slit in each olive with a sharp knife and place them in a 5 litre food quality bucket.
  • Cover with brine and put a plate on top to keep them submerged.  
  • Leave them for a week and drain off the brine.  Rinse the olives, replace with fresh brine and leave for another week.
  • Do this for 3 weeks and then taste the olives.
  • If they are still too sour, repeat the process, checking the taste of the olives every week until they are OK.
  • Bottle them in fresh brine, cover with about 5mm of extra virgin olive oil to protect them and store them until required.
  • If you leave your olives on the tree until they are black, they will cure a lot quicker.
  • Here is an alternative from Nadine in Athens. 
Organic Pest Control.
  • Greenhouse whitefly.  
    • Monthly foliar sprays of aerated compost tea toughens foliage against whitefly damage. 
    • Control any serious infestations by spray your crop thoroughly with organic horticultural oil (Eco-oil in Australia) as early in their life cycle as possible.  
    • Spray again in a few days to ensure second generation whitefly do not survive.
  • General.
    • My olive tree has been pest free since I planted it 5 years ago.  Even the whitefly who visit the tree from surrounding plants when they emerge in spring, do not seem to cause any damage on the olive's tough foliage.
    • Regular applications of aerated compost tea boost the natural defences of olives by colonising the leaf surfaces with beneficial microbes.  They defend the plant against airborne pests and diseases.
    • Similarly, proper soil preparation including regular applications of home made compost boosts the community of beneficial microbes, which defend the tree's roots against plant pathogens.