Olive Care Guide


Round-headed, sub-tropical evergreen tree that needs mild winters. Grows about 20 tall outside in Zones 8-9. Possible origin Mediterranean region, cultivated since 3000 B.C. Can grow in greenhouse or pot cultivation. The fruit can be pressed for oil or cured.  The olive tree lives longer than any other cultivated fruit tree, with the exception of the mango.

In character the olive tree is round-headed and bears numerous branches which bend downwards and give it a thick bushy appearance. With very old trees the trunk, especially near the base, gives the impression of a group of trunks. It's leaves are evergreen and leathery, and have a dusty, ash-like appearance. under natural conditions the tree grows to about 30'.

With the loquat, feijoa, and citrange the olive tree can withstand lower temperatures than any of the other cultivated evergreen fruit trees. A healthy, well-nourished tree will make a fairly good recovery even though it's wood may have suffered considerable frost damage, but it has greater difficulty in doing so when it's resistance has been lowered by heavy fruit-bearing in the previous season. In general a temperature below 14 degrees F (-10C) my cause considerable injury to a mature tree but (with the exception of juvenile trees) a temperature of 16 degrees F (-9C) will normally cause no harm. The flowers and young shoots are, of course, tender but the tree blossoms in summer so that no damage is done to these.

The olive is more resistant to transplanting than most other evergreen trees. Although the tree will be seen growing and bearing it's fruit on poor, shallow soil-and doing this better than most other fruit trees-it will in fact produce much more fruit when grown in a good soil. A good sandy loam should, therefore, be provided and it should be allowed to occupy a sunny position either in a large pot or in the greenhouse border.

After the first year, four or five shoots on the stem should be selected and the others removed. The elected shoots should be cut back to 6" and the following year the shoots which grow from these are again thinned out and a few selected and cut back. This is done for 3 years and results in a young tree with a spreading head and branches arranged symmetrically. In succeeding years all that needs to be done is to thin out crossing branches and allow as much light as possible to get to all parts of the tree. To stop the tree from getting too big the branches may be shortened.

Olive trees require a cool period during the winter to stimulate or induce good flowering. Temperatures should be allowed to fall below 40*F (4*C).

The creamy white flowers appear i early summer and are borne i short panicles i the axils of the leaves. The flowers are either perfect (containing both female & male part) or male only (containing only male pollen-producing parts). The pollen, normally shed plentifully, is carried by the wind and pollination is effected by this means. During the blossoming period some humidity is required to encourage a good set of fruit.

Although the olive tree does bear fruit quite well in areas where the annual rainfall is low it will, other factors being equal, produce far better crops where the rainfall is adequate. Therefore, when the tree is grown in a pot it should never be neglected so that it suffers a shortage of water. Also if the temperature in the greenhouse is high and the air dry, this may cause excessive falling of immature fruit.

In a warm sunny climate the oil content and weight tends to be at it's maximum 6-8 months after blossom time, but the fruits can be allowed to remain on the tree much longer than that if they are to be used for oil. As they ripen their color changes from green to straw color to rosy pink, to red, to black.

When the fruits are used for oil they should have turned black before they are harvested.

For pickling the fruits may be gathered whilst they are still green, but this must be done carefully to avoid bruising. All raw olives have a bitter taste which is removed quite easily by placing them in a solution of 2 oz sodium hydroxide per gallon of water and leaving them in this until their color begins to change. They should then be put into fresh water daily for 2 or 3 days to remove the salt solution. After this they are put into brine.

Source: Simmons, 'Growing Unusual Fruits'

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