OLIVE TREES - (Back)

BACKGROUND

Olives are hardy outside only in the mildest situations, the most famous being the one in the Chelsea Physic Garden which ripens fruit from time to time.
Otherwise they will grow well in tubs and can be trained to any desired shape.
In spring they cover themselves with tiny yellow flowers which are highly fragrant, followed by fruit which ripen black. Their silver grey foliage provides a distinct Mediterranean atmosphere.

The olive requires a long, hot growing season to properly ripen the fruit, no late spring frosts to kill the blossoms and sufficient winter chill to ensure fruit set. The tree may be grown as an ornamental where winter temperatures do not drop below 12° F. Green fruit is damaged at about 28°f, but ripe fruit will withstand somewhat lower temperatures. Hot, dry winds may be harmful during the period when the flowers are open and the young fruits are setting. The trees survive and fruit well even with considerable neglect. Olives can also be grown in a large container.

The olive is an evergreen tree growing to 10-12ft in a container. The attractive, gnarled branching is also quite distinctive. Olives are long-lived with a life expectancy of 500 years.
The small, fragrant, cream-colored flowers grow on a long stem arising from the leaf axils. The flowers are largely wind pollinated with most olive varieties being self-fertile, although fruit set is improved by cross pollination with other varieties. The olive fruit is a green drupe, becoming generally blackish-purple when fully ripe. A few varieties are green when ripe. The cultivars vary in size, shape, oil-content and flavour. Thinning the crop will give larger fruit size. This should be done as soon as possible after fruit set.

THE CULTIVATION OF OLIVE TREES

The olive tree legend found its roots in Greek mythology. When Greeks were looking for a God to protect their town, Athena, the Goddess of Wisdom, made an olive tree grow from the ground to gain their favour. So pleased by this everlasting tree which provided food and oil, they called their new capital Athens. The Olive tree now signifies peace, wisdom, eternity and continual rebirth.

Olives will grow well on almost any well-drained soil up to pH 8.5.

Winter - Keep frost free, and the lower the temperature of the greenhouse the less water the plant will require.  Lightly prune any ungainly branches.  Check the stems and leaves for any scale insects.  Clean off with soapy water if necessary.

Spring - Repot if required into a pot which is two sizes larger - or if a mature plant remove from pot and gently tease off some of the soil and repot back with fresh compost - using John Innes No 2 with extra bark if required to improve drainage.

Summer - Stand outside for most of the summer, and feed weekly with a balanced fertiliser.  Prune the
tree to keep a good shape, and pinch back the young shoots after about 4 - 5 leaves.  Severe pruning of plants that have been neglected or allowed to grow out of shape can be done in June.  Regular checks should be made for the appearance of scale insects.  Our olives are self-fertile but it does help if when the tiny flowers appear to lightly shake the plant or brush the flowers with a soft brush or rabbits tail.

Fruit. Olives are NOT edible straight off the tree.

To pickle them take 2lb green or black olives, 4 oz of salt, 1 lemon quartered. 1 teaspoon of dried oregano, 1 tablespoon of chopped fresh thyme, 1 garlic clove halved.
Prick the olives and put into a plastic container and cover with cold water, leaving them to soak for a week, but changing the water every other day.  Drain.  Make up a brine with the salt and 4 pints of water.  Cover the olives with the brine and add the rest of the ingredients.  Leave for 2 weeks, they are then ready for use.

PRUNING OLIVE TREES

A subject deeply complicated by the mists of time and, no doubt, by suspicious growers trying to protect their secrets.

An Olive tree when mature is a very forgiving plant and may be pruned to within an inch of its life but a young tree cannot accept any bar the mildest of pruning. Many young trees are imported as small, tight headed standards, very heavily pruned, these can take years to establish and shape before you will get them to crop successfully.

So, to begin with the ideal tree to plant is a young, straight stemmed example 4-5ft in height, with a few feather branches forming at around 3 or 4 ft.
Plant in the normal manner with a deeply dug hole and well drained fertile soil.
Very little pruning should be done in the next 3-4 years. At most take out the tip to encourage the side branches and then wait until the tree is established successfully.

Now you have a tree 4yrs older, with lots of vigorous young growth and it will need a good thinning and opening up. Some say you need to allow enough space for a bird to fly through it, but which bird, a Sparrow or a Pheasant?  The best way to look at it is to follow the glass or goblet shape, imagine a glass that is like an old, wide Champagne glass, not a modern flute. 
Start by looking for 3 to 5 scaffold branches to form the main arms, those coming out side ways at a low angle are ideal, aim to get the angle between each of them at around 90 degrees. These will then give you an approximate ‘X’ shape when looked at from below, and form the basis on which the tree will shape itself for the future.The next job is to remove any crossing or damaged branches then look at your tree again,(from below), and whilst you are looking at it from that angle -( lie down on the grass !) check to see if you can clearly see the sky, that gives the best view as to how much wood may need removing to open up the tree.
Your aim is to leave a single up and out shoot on the top of each of your main arms. That is three or four on the ideal tree. All the other verticals should be removed. The problem is to distinguish the verticals, some go straight up, that is clear and simple. Others go out at forty-five degrees. These are laterals that will bend down under the weight of olives and produce abundant crops. In between there are all sorts of angles that you will need to make a judgement about whether to remove or leave.
Having removed the verticals which will be mostly around the top of the tree, you need to thin the hanging branches that have become weak. These will be towards the inside of the tree and it is often better to tackle them from inside the skirt of the tree. The growth of this fruiting wood is the mirror image of the upward growth. Whereas the upward growth was moderated into a zigzag path of out before up, the fruiting wood zigzags down. By cutting off the last zig or zag you will allow new lateral shoots above to replace the tired wood. Again judgement plays an important role. The dead wood on the inside is obviously pruned off. The vigorous laterals on the outside will produce abundant fruit. In between you must decide which should come off as weak and which are worth leaving for another season.

Light air and sun are needed to keep the tree disease free and to let the sun ripen the wood well enough to crop the following year. It is worth noting now that an Olive will only fruit on wood once , young vigorous wood is always needed to replace the old .
Plenty of water and feed to keep the tree cropping well into its dotage.

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