OLIVE BONSAI

The Olive Bonsai: The Immortal King of the Mediterranean

The Olive (Olea europaea) is not just a tree, it is a living monument. In bonsai it stands for strength, survival and austere beauty. It is perhaps the species most loved by Italian bonsai growers for its incredible longevity and resilience. What makes the Olive a masterpiece is its bark, which becomes rugged and sculptural, the wood that, as it dies, creates natural silvery jin and shari (deadwood), and its ability to reduce leaf size drastically with the right cultivation.

Origin & species

Native to the Mediterranean basin, the Olive is an evergreen plant.
In bonsai two main types are distinguished:
Cultivated olive: the one we get oil from. It has larger, more rounded leaves.
Wild olive (Olea europaea sylvestris): this is the wild form. It is the favourite of bonsai growers because it has naturally tiny leaves, short internodes and develops much more twisted trunks, rich in deadwood (sabamiki), than the cultivated variety.

Exposure and microclimate

The Olive demands full sun.
Do not be afraid to expose it to direct sunlight even in August (except for very small pots). Sun is the only way to obtain small, compact leaves and short internodes. It loves wind and open air. If kept in the shade or indoors, it weakens quickly, the branches stretch out and it becomes easy prey for scale insects.

Watering

Although in nature it is drought resistant, in a pot it needs a regular but controlled water supply.
Let the soil mix dry out well between one watering and the next. The Olive fears waterlogging more than thirst: permanently soaked soil leads to root rot. However, in summer, when it is in full sun, it drinks a great deal and must be watered generously.

Water quality

It is a tough, tolerant plant. It accepts tap water even if hard, being used to the basic, rocky soils of the Mediterranean. There is no need to acidify the water.

Substrate

Drainage must be perfect. The Olive likes stony, airy soils.

Recommended mix: 60% pumice (essential for the Olive), 30% akadama (or lapillus) and 10% general purpose soil mix.
Pumice is the secret ingredient for Olives: it holds the right amount of moisture without suffocating the roots and releases useful trace elements.

Repotting

Carried out in spring (March-April), when the plant starts to move its buds.
The Olive is very robust: it takes even drastic root pruning well (often necessary on collected specimens, or yamadori). Repot mature specimens every 3-4 years. Use pots that are not too deep, to emphasise the base of the trunk (nebari).

Fertilizing

Fertilize from spring to autumn with solid slow-release organic fertilizer.
If you are working on fine ramification and want small leaves, do not overdo the nitrogen. Suspend fertilizing in the hottest months (July-August) and in winter.

Flowering and fruiting

It flowers in spring with clusters of small white/yellowish flowers, followed by olives in autumn.
The flowers are borne on the previous year's branches. If you prune everything in winter, you will have no flowers. Bear in mind that ripening olives takes a lot of energy: on a bonsai in training it is better to remove them.

Structural pruning

Large cuts are made in late winter. Olive wood is extremely hard.
It is essential to use sharp tools and to cover the cuts with cut paste, even though the Olive tends to compartmentalise well. Often useless branches are not cut away completely, but stripped of their bark to create jin (dead branches), which add age to the plant.

Maintenance pruning

During the growing season the Olive produces long, vigorous shoots that must be shortened to keep the shape of the canopy. Always cut leaving a couple of leaves; the Olive buds back very well, even from old wood.

Pinching

To thicken the foliage pads, the soft shoots are pinched back when they have produced 4-5 pairs of leaves, reducing them to 1-2 pairs. This operation is carried out throughout spring and summer.

Wiring & bending

Be careful: Olive branches become stiff and brittle very early.
Wiring is done on young branches. To bend old, thick branches wire is not enough and you risk breaking them: use guy wires and proceed in stages, lowering the branch a little at a time over the months.

Diseases and pests

Scale insect (half peppercorn scale): enemy number 1 of the Olive. It creates dark shields on the branches.
Peacock eye (Cycloconium): a fungus that creates round spots ("eyes") on the leaves, making them yellow and drop. It is prevented with copper-based products and by placing the plant in sun and open air.
Sooty mould: black film on the leaves, a consequence of the honeydew produced by scale insects.

Winter & protection

In the South and in coastal areas it lives outdoors all year round without problems.
In the North, although hardy, the roots in the pot can suffer if the root ball freezes completely for days. Protect the pot with horticultural fleece or put it in a bright cold greenhouse if temperatures drop steadily below -4°/-5°C.

Yearly calendar

January-February: deadwood work (jin/shari), structural pruning.
March-April: repotting, preventive copper treatments.
May-June: pinching, fertilizing, full sun.
July-August: careful watering, rest.
September-October: autumn fertilizing (PK), cleaning.
November-December: winter protection (in the North), lime sulphur on the deadwood.

Useful products for this bonsai

Frequently asked questions about Olive bonsai

Why is my Olive dropping its leaves, and why do they have round spots?
It is peacock eye (Cycloconium oleaginum), a very common fungus when there is stagnant humidity. Treat with copper-based products and move the plant immediately to a more ventilated and sunny spot.

Can I keep it indoors as decoration?
The Olive suffers greatly indoors. It needs the cycle of the seasons and, above all, an amount of direct light that no lamp or window can match. If you keep it indoors it will survive for a while, but it will lose its leaves and weaken until it dies.

How do you bleach the deadwood?
The characteristic white part of olive bonsai (jin and shari) is obtained by brushing the dead wood (clean and dry) with jin liquid (lime sulphur, calcium polysulphide). This treatment bleaches the wood and protects it from rot. It should be done 1-2 times a year, preferably in summer under the sun.