Shirley Walker of the Eden Project explains how to grow an olive tree and bring a touch of Mediterranean magic to your garden
Shirley says: My love affair with the olive began many years ago on the Ionian island of Paxos. I was captivated by this ancient and beautiful tree, brought to the island by the Venetians in the 15th century.
The history of the olive, however, stretches back much further and it was one of the most powerful symbols of the Ancient World.
Indeed, the olive has been a part of everyday life in the Eastern Mediterranean since the beginnings of civilisation more than 6,000 years ago. It began life as a sprawling, spiny shrub in the Levant (present day Syria and Lebanon).
Thousands of years of selection and breeding have turned it into the productive tree we know today.
The olive is now an integral part of the Mediterranean landscape and the most important economic plant in the region, with 800 million trees in cultivation.
In spring the silvery canopy is covered in tiny flowers, like scattered stars. The swaying branches protect a wealth of spring bulbs and wildflowers beneath then, like cyclamen, poppies, field marigolds, purple viper’s bugloss and tassel hyacinths. During long, hot Mediterranean summer the trees become heavy with fruit, ripening from green to black as the winter approaches.
Olive trees are extremely tough and can withstand searing heat, drought, fire and freezing temperatures.
I really admire mediterranean plants because they have adapted over thousands of years to cope with extreme climatic conditions. They can handle poor soils with ease and also cope well with the effects of fire, which can be an all-too-common occurrence in such tinder-dry conditions.
Many Mediterranean plants, including the olive, have the capacity to regenerate from the base when damaged by fire – that’s how the olive came by its name ‘tree of eternity’. Our olive grove in the Mediterranean Biome here at the Eden Project contains some old, gnarled specimens but these are mere juveniles compared with some you find – carbon dating of specimens in Lebanon has revealed trees several thousand years old. I find it amazing that these trees have been producing fruit and giving oil since Biblical times.
This wonderful, evergreen tree will add a touch of the Mediterranean to any garden. Olive trees are becoming increasingly popular in milder parts of the UK.
When I’m working in the Mediterranean Biome, visitors frequently ask me how they should care for their young olive trees.
The answer is that olives can thrive in containers or in a sunny, well-drained spot in the garden.
When you buy your tree, pot it on into a larger pot, preferably terracotta rather than plastic, and use a loam-based compost like a John Innes no. 3. Add 20% horticultural grit to improve the drainage.
Place in a sunny position, keep the soil moist during the growing season and feed with a balanced liquid fertiliser once a month. In winter you can reduce watering but don’t allow the compost to dry out completely.
If your tree is going directly into the ground, plant in spring, after the risk of frost has passed, but before the end of June to give it plenty of time to establish before winter.
Olives grow very slowly so don’t require much pruning when young. Container-grown plants tend to grow more quickly, so if the canopy becomes dense, remove some of the branches to let more light into the centre. Keep an eye on the shape of the tree and remove any dead or diseased wood. Olive trees flower and fruit on one-year-old wood.
Trees should begin producing fruit at about three to five years old. Most olive varieties are self-fertile but they are wind pollinated, so will need to be outdoors when in flower. We use a leaf-blower to pollinate our olive trees in the Biome!
Olives need a two-month cold spell in winter, and fluctuating day/night temperatures to initiate flowering and fruiting. So keep container-grown trees in an unheated conservatory or greenhouse over winter, with plenty of light.
Some cultivars do better outdoors in the UK than others. I recommend Arbequina, a small tree from Catalonia in northern Spain, with weeping branches, ideal for small gardens. For larger gardens, Cipressino is a vigorous tree with an upright growth, originating in Puglia, Italy. Its name comes from its similarity to the Italian cypress.
Leccino comes from Tuscany, Italy and is a popular variety with open, pendulous branches. It is easy to grow and will tolerate a wide range of temperatures. Picual, originating in Andalusia, Spain is an extremely hardy and vigorous tree requiring regular pruning and finally, Pendolino is a small, compact, weeping form with architectural appeal from Tuscany. It will need a pollinator to provide fruit as unlike most olives, this one is self-sterile.