Olive tree, <em>Olea europaea</em>: planting, pruning

Description and botany

Emblem of Mediterranean landscapes, Olea europaea or common olive belongs to family Oleaceae like lilacs. Cultivated since time immemorial for its green or black fruits and for its oil, it occurs naturally in dry, rocky soils around Mediterranean basin, from Africa to central Asia, even in Australia. Genus includes about thirty species, among which Olea europæa is most widespread. Nearly 2,000 olive varieties are recorded; ‘Olivier Lucques’, ‘Aglandau’, ‘Bouteillan’, ‘Cailletier’ or ‘olive de Nice’, ‘Picholine’, most common in France, are among best-known cultivars.

Olive’s slow growth matches its exceptional longevity that can exceed 3,000 years! It shows a picturesque habit, upright with a rounded crown, spreading and becoming more pronounced with age. Olive takes on a characteristic distorted aspect with age, its bark grey and fissuring over time. It may assume varied silhouettes, with a single trunk or multiple trunks, branches erect or nearly pendulous depending on variety. Tree produces suckers, called “souquets”, at trunk base.

While it can reach 15 to 20 m in wild state, it generally does not exceed 2 to 10 m in height in cultivation.

Evergreen and leathery foliage covers branches clothed in peltate scales. Foliage renews constantly, leaves living about three years. Leaves are opposite, entire or irregularly dentate, ovate to elliptical, elongated with prominent midveins. Measuring 3 to 9 cm, they are glossy dark green or grey-green above, with a silvery, downy underside.

Olea europaea – botanical illustration

In spring, from April to June depending on climate, this bushy, bluish crown trembling in wind is covered with a discreet and fugacious white flowering. Countless small white or cream flowers 2 to 5 mm long, gathered in small clusters in leaf axils, open on previous year’s wood, adding to its charm. Tubular corolla formed of four rounded petals reveals yellow stamens laden with pollen that can be allergenic.

Although this flowering lasts only about a week, it is very nectariferous, attracting numerous pollinating insects such as bees.

Fruit set in olive occurs only in warm regions and only after 7 to 10 years of growing, although some varieties crop sooner. Tree can then fruit until around 150 years of age. Most olive trees are self-fertile, while others will require presence of another olive tree pollinator to fruit.

In summer, flowers then transform into fleshy drupes with a hard stone, 2 to 4 cm long — olives, first a lovely pale green, then purple and finally black at full ripeness. They are sometimes covered with a thick bloom, and taste so bitter that they are inedible raw. These lipid-rich fruits vary by variety: elongated, crescent-shaped and very smooth in ‘Lucques’, spherical or ovoid in others.

Depending on region, olive harvest takes place in autumn or winter. It takes about 4 to 6 kg of olives to obtain one litre of oil and to prepare them to remove all bitterness. Preparation methods are so laborious that it is far preferable to grow olive in garden only for its iconic Mediterranean beauty.

Common olive is planted across France but grown differently from region to region. From its Mediterranean origins it retains some chill-sensitivity preventing survival below about -10 to -12°C, sometimes down to -15°C in well-drained soil. Outdoor cultivation should therefore be reserved to the area called “olive zone”, in regions with mild winters and dry summers! North of Loire, it will acclimatise without problem in a large pot to be protected from severe cold during winter.

Olive requires a sunny position, sheltered from cold winds, and deep, well-drained soil, even stony or calcareous; it dislikes only waterlogged soils.

Flowering and fruiting of olive

With its twisted silhouette, common olive is a very ornamental tree that benefits from being planted in isolation. Essential in Mediterranean-inspired dry gardens, it can also be placed at centre of a border, as an avenue tree, or as a windbreak. In cold regions, in a large container, it brings an exotic note to terraces and balconies.

Its wood is so hard that it is highly prized in cabinetmaking, sculpture and for making kitchen utensils. Its oil ranks among best table oils and is also much valued in cosmetics. Olive leaves have medicinal properties — digestive, diuretic and antihypertensive.

Presence of olive dates back to time immemorial; this legendary tree is a symbol of peace. In ancient Greece, victors at the games were also crowned with olive branches representing strength and victory.

Main species and varieties

The genus comprises around thirty species of olive, the most widespread being Olea europaea. It includes many varieties. Those we offer are easy to grow, attractive and robust, within reach of all amateur gardeners.

Most popular

Olea europaea Stem - Olive

C'est l'Olivier typique au tronc noueux, et au feuillage argenté. Il évoque la chaleur et le soleil du Midi ! Peu rustique, vous pouvez l'adopter dans un grand bac dans les régions froides !

• Flowering time July
• Height at maturity 9 m

See the product sheet

Olive Tree - Olea europaea

C'est l'olivier emblématique des paysages méditerranéens au tronc noueux lorsqu'il prend de l'âge, couvert d'un feuillage gris-vert. Peu exigeant sur la nature du sol, quelque peu frileux, il résiste au gel modéré de l'ordre de -8 à -10°C, en sol drainé.

• Flowering time July
• Height at maturity 9 m

See the product sheet

Olea europaea Stem - Olive

Un petit arbre persistant au tronc torturé coiffé d'une couronne argentée. Nous vous le proposons sur tige, il s'installe en pleine terre comme en grand bac !

• Flowering time July
• Height at maturity 9 m

See the product sheet

Planting an olive tree

Where to plant an olive tree?

Olea europea or common olive is planted throughout France, but is grown differently depending on region. It is a relatively frost-sensitive tree, nevertheless capable of withstanding short frosts of around -10°C to -12°C, in well-drained soil.

It is easy to grow in regions with mild winters. In open ground, reserve it for Mediterranean climates, with hot, dry summers because it does not tolerate excess water. Elsewhere, grow it in a large pot, an orangery tub for example, and move it under cover to protect from frost in the cold season.

It requires a sunny spot sheltered from prevailing cold winds and draughts, particularly in less favourable regions.

Particularly suited to Mediterranean climate, it is very drought-resistant and undemanding regarding soil type: it will settle for ordinary, deep soil and is capable of prospering in poor, stony ground provided it is permeable and well drained. It dislikes heavy, waterlogged soils where water stands: it will naturally find its place on a large arid bank.

Easy to grow in a pot as well as in open ground, it gives gardens and terraces a Mediterranean feel. It can be placed in centre of a summer border, as an avenue tree or even in a windbreak hedge.

When to plant an olive tree?

Olive is best planted in late spring, once risk of frost has passed because young olive trees are particularly vulnerable to cold. Our container-grown plants can be planted all year round in regions with a very mild climate.

How to plant an olive tree?

Olive prefers well-drained ground. In open ground or in a pot, follow Ingrid’s advice to plant an olive correctly.

In open ground 

Space olive trees 6 to 8 m apart in all directions. If your soil retains moisture, do not hesitate to plant it on top of a mound, where water will not stand.

• Loosen soil well and dig a hole three times wider than the rootball
• Add a good layer of pozzolana, river sand or gravel to the bottom of the planting hole
• Use a stake to protect it from strong winds
• Backfill with potting compost and sand mixed with the excavated soil
• Keep the olive upright then fill in the hole
• Firm down with your foot then form a basin around the base
• Water well at planting then regularly in dry weather during first year after planting

In a pot 

Substrate must be very free-draining to avoid rot relating to root and stagnant moisture at the base of the Olive.

• In the bottom of a container at least 2 to 3 times larger than the volume of the rootball, spread a good layer of drainage material
• Plant in an equal-parts mix of potting compost and garden soil with a little sand added
• Use a stake suited to the size of your olive tree
• Water well at planting
• Move the pot under cover to protect from frost in autumn in cold regions

⇒ To find out more: Growing an olive in a pot

Growing an olive tree in a pot is entirely possible… makes a striking feature on a terrace!

When and how to sow olive seeds?

Les olive tree seeds are sown from March to June, be patient, germination is slow and somewhat erratic!

• Scarify seeds with a knife: nick the surface of seeds with a sharp knife, or scratch them with sandpaper to ease germination and water penetration
• Plant seeds in individual buckets
• Keep substrate moist, but not waterlogged during germination which takes several months
• Keep sowings warm at 20-25°C
• Pot on into larger pots following spring; wait one year before planting your young olive plants outdoors

Maintenance, pruning and care of olive trees

In open ground

Olive trees are easy to grow in favoured regions where frost is neither severe nor prolonged. They need regular watering during their first two years to establish well.
Once well established, they become increasingly drought-resistant. In summer, water once or twice a month, taking care not to waterlog the soil.

Add a little well‑rotted compost around the tree base in spring and autumn to encourage growth.

The top of young olive trees planted in open ground can be protected with a winter fleece during the first years before cold weather arrives to help them through the winter.

In pots

Water potted olive trees in pots very regularly, allowing the soil to dry between waterings and without letting water stand in the saucer.

In autumn or spring, repot every 2 or 3 years into a slightly larger container or simply replace surface soil with fresh potting compost.

Frost can kill it below about -10°C: in cold regions, store the pot from October to March in an unheated or lightly heated greenhouse or conservatory where temperature does not fall below 10°C, and return it outdoors as soon as temperatures rise.

Pruning of the olive tree

Pruning an olive tree is carried out in spring, from March to mid‑May. Pruning an olive grown for ornamental purposes is not demanding: it is light and helps maintain an attractive habit and strengthen the trunk.

Each year, carry out a spring clean‑up and a thinning prune by removing dead and tangled branches to open up the centre of the branches:

• Clear the trunk by removing the least vigorous branches
• Remove any suckers at the base of the trunk
• In the south, to encourage olive production, prune every 2 or 3 years because fruits appear on the previous year’s wood

⇒ Also read: Pruning the olive tree: regularity, methods and advice… Everything you need to know!

Pruning the olive tree

Possible diseases and pests

Olive tree is a resilient tree that can survive for centuries! However, although hardy, olive tree has a few well-known pests that are rarely fatal, mainly troublesome for fruit production. An infested olive tree is easy to treat.

Among its notorious enemies, the olive fruit fly is the most feared because it makes fruit unsuitable for consumption: a few pheromone traps and sprays of a clay-based solution can be enough. Olive thrips are small sucking flies that deform leaves and fruit but usually do not require treatment, black scale causes sooty mould on leaves; prevent with sprays of oil and black soap or, more simply, Bordeaux mixture in early spring.

Bark beetle and olive moth are more troublesome because they attack young shoots and flower buds: cut and burn affected branches as soon as they appear dry or diseased. Olive pyralid, a small moth, causes little damage.

If edges of young leaves are eaten in an arc, otiorhynchus weevil is devouring them!

On the disease side, olive tree is especially vulnerable to fungal diseases linked to excess moisture in the soil and poor drainage. Most are not serious.

Root rot and verticillium wilt are the rare true deadly diseases for olive tree: the first attacks the roots causing gradual decay of the entire tree, the second causes sudden drying out of one or more branches. The only real prevention is to plant olive tree in light, free-draining soil that does not retain water because there is no effective treatment.

Peacock eye (Cyclonium oleaginum) is also a frequent disease that causes circular yellow or brown spots on olive leaves, weakening the tree; it particularly affects potted olive trees. Affected leaves eventually turn completely yellow and fall: as a preventive measure, apply sprays of Bordeaux mixture.

The canker of olive appears as warty growths or “cankers” on the wood; it is common on fruit trees and is mainly unsightly: cut and burn affected branches.

In general, to avoid most of these diseases: spare olive tree heavy, wet soils, avoid overwatering and avoid watering leaves directly.

Rabbits love olive bark: protect young trunks with wire mesh.

Finally, in recent years olive trees in Corsica and Italy have been affected by the killer olive bacterium: Xylella fastidiosa, responsible for the Olive Quick Decline Syndrome (CoDiRO). Against this “olive plague” there is currently no treatment.

→ Find out about diseases and parasites of olive tree and about the canker of olive: identification and treatment in our advice sheets!

→ Discover our advice on getting rid of psyllids

Propagation

Although olive tree can be propagated by olive tree by sowing (see above), by semi-ripe cuttings, layering or grafting (see our tutorial How to propagate olive tree?), we recommend instead the propagation by suckers, which is much quicker and less tedious provided garden has an old stump already well established.

By suckers

• In spring, use a mattock to detach from base of trunk a well-rooted sucker
• Replant immediately in garden in well-prepared, free-draining soil
• Prune severely to encourage regrowth

Pairing olive trees with your garden

Staple tree of sun‑baked Mediterranean gardens, Olive is also an asset in a mineral garden, surrounded by rockery plants.

It is perfect alongside Mediterranean perennial plants undemanding such as Santolina, rosemary, Artemisia, sedums, lamb’s ears or even Spanish grass, creating a lovely harmony of silvery foliage.

One planting idea in mild climate: Olea europaea, Phormium ‘Pink Stripe’, Santolina ‘Edward Bowles’, Rosmarinus officinalis, Pittosporum tenuifolium ‘Golden Ball’, Geranium renardii and Euphorbia characias ‘Purple and Gold’

In mineral scenes, pair its gnarled silhouette with plants that enjoy same growing conditions such as agaves, blue oat grass, blue fescue, Eryngium.

Its grey‑green foliage reveals itself in fresh, very soft palettes. In that spirit, for a chic, classic look, lavender planted in a line at its feet is magnificent, as are shrub roses with pink or white flowers. In a flowering hedge, it sits easily alongside some summer‑flowering bushes such as Cistus and Lavatere, white and pink almond trees, creating delicate, romantic compositions.

It also stands out with oleanders, holm oaks, cypresses and myrtles.

The blue‑tinged colour of its leaves pairs easily with complementary tones such as yellow of Helenium, Echinacea, euphorbias and with glaucous or grey tones of foliage from an Artemisia or a Helichrysum italicum.

While it looks good planted singly on large sunny banks, it can be centrepiece of a large bed surrounded by perennial plants with summer flowering such as daylilies, agapanthus, dianthus plumarius, irises and dry‑soil perennials such as Gaura, Nepeta, love‑in‑a‑mist, Erigeron karvinskianus, Epilobium or Salvia.

Garden scene with an olive, a smoke bush (‘Grace’, ‘Royal Purple’…), roses, hardy geraniums, sedums, achilleas, larkspur…

Further north, it is grown in large tubs alongside aubrieta, Osteospermum and dianthus.