How to grow olives

What are olives?

Olives are evergreen, small- to medium-sized trees native

A native plant is one that originated or arrived naturally in a particular place without human involvement. In the British Isles, native plants are those that were here during the last ice age or have arrived unaided since.

to the Mediterranean region. Their leathery green leaves are coated in small, white hairs giving them a silvery appearance. The creamy-white flowers may occasionally produce fruit (technically called a drupe) in hot summers in some parts of the UK. The fruit requires special preparation to make it edible.

Choosing olives

Olea europaea  is commonly available in the UK in many sizes from mature old trees with beautifully gnarled trunks, which make the perfect focal point in a large garden, to half standards that take up very little space. As olives rarely produce fruit in the UK, they are best chosen for their shape or foliage.

How to choose healthy plants

Buying: trees and shrubs

In the ground

Planting in the ground is best carried out in spring to ensure good establishment in the warmer conditions of spring and summer. However, olives can be planted at other times of year as long as the ground isn’t frozen or waterlogged

Describes soil or potting compost that is saturated with water. The water displaces air from the spaces between soil particles and plant roots can literally drown, unless they are adapted to growing in waterlogged conditions. Waterlogging is common on poorly drained soil or when heavy soil is compacted.

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Select a sunny, sheltered site away from cold winds on well-drained soil. Heavier soils will need improving by incorporating well-rotted organic matter (such as homemade garden compost

Can refer to either home-made garden compost or seed/potting compost: Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.

) to improve drainage. Larger plants will need to be staked for a couple of years until established.

Organic matter: how to use in the garden

Trees and shrubs: planting

In containers

In colder areas or on heavier, wetter soils, plants are best grown in large containers that can be placed in a sunny, sheltered spot outdoors in summer, then moved into a frost-free place over winter. Preferably plant in a thick, frost-proof container with a minimum width and depth of 30–35cm (or large enough to accommodate roots easily). Ensure there are plenty of drainage holes in the base of the container. Use a peat-free, soil-based compost

Soil-based compost is a potting compost that includes sterilised soil/loam in the mix. As loam contains sand, silt and clay, it does not rot down like organic materials, so adding soil/loam to compost ensures it is longer lasting – it is often used for shrubs in pots and will last 3–4 years without the need to be replaced.

, such as John Innes No. 3, and mix in some horticultural grit (about 20 per cent by volume) to improve drainage.

Trees: growing in containers

Watering

Plants growing in the ground require watering during dry spells until they become established. Once established, they are drought tolerant, only requiring additional watering during extremely prolonged hot, dry, sunny spells.

Container-grown plants will need regular watering from April to late September when the plant is in active growth. Over the winter just keep the compost

Can refer to either home-made garden compost or seed/potting compost: Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.

barely moist and raise pots off the ground on pot feet or bricks to prevent them becoming saturated.

Watering

Feeding

There is no need to feed plants growing in the ground unless they are showing signs of nutrient deficiency. Mulching with your own homemade compost or bought-in, well-rotted organic matter, will slowly release nutrients

To grow well, plants need a wide range of nutrients in various amounts, depending on the individual plant and its stage of growth. The three key nutrients usually taken up from the soil are nitrogen, phosphorus and potassium. Plants also need carbon, oxygen and hydrogen to make carbohydrates — their main energy source. Carbon and oxygen come from the air as carbon dioxide, while hydrogen is drawn from water absorbed by the roots. Other important soil nutrients include magnesium, calcium and sulphur. Most garden soils contain enough of these nutrients to support healthy plant growth.

into the soil as it breaks down.

Give container-grown trees a boost by replacing the top layer of compost annually in spring. Carefully scrape away about 5cm of compost from the surface and replace with fresh compost (see Planting in containers above for compost mix).

How to feed plants

Nutrient deficiencies

Trees: growing in containers

Overwintering

Many olives are hardy through most of the UK, tolerating temperatures of -5 to -10°C. However, leaves and branches can still be damaged by severe frosts (see Problems below). 

In very cold winters, plants can be protected by wrapping a couple of layers of biodegradable

Anything that can be decomposed by fungi, bacteria and micro-organisms, so it doesn’t persist indefinitely in the environment. Biodegradable plastics are usually made from plants, such as bamboo, rather than fossil fuels. Ideally, products that claim to be biodegradable should break down quickly and leave nothing harmful behind. However, they may need specific conditions in order to biodegrade successfully or may produce greenhouse gases such as methane in the process.

fleece

A soft, fibrous, translucent material laid over or around plants hastening their growth and protecting them against weather and pests. Heavier grades of fleece give about 2°C of protection from frost. It is usually used without supporting hoops.

or hessian around the canopy to prevent weather damage caused by cold winds and frost. 

Containers can be moved undercover or placed in a sheltered position away from cold winds, with the container and canopy wrapped to protect against severe frosts.

In milder weather, the wrapping can be removed and replaced when severe frost

A severe frost is a frost with a temperature below -5°C (23°F).

is forecast.

Overwintering tender plants: wrapping

Olives grow slowly, so don't require much pruning. In late spring or early summer, remove dead, diseased or dying branches, pruning back to a sideshoot. At the same time, thin out branches to allow light into the centre of the tree and remove any branches that spoil the shape. Prune off any shoots that are growing from near the base or along the trunk if a clear stem is to be maintained.

Container-grown plants may need additional summer pruning to keep their size in check. When plants in containers get to about 1.5m, pinch out

Removal of a plant’s growing tip (usually with finger and thumb) to encourage it to produce side-shoots, forming a bushier, well-shaped plant that will bear more flowers and/or fruits.

the tips to encourage branching. 

Young trees can be trained by referring to our formative tree pruning guide below.

Shrubs and trees: light pruning

Trees: formative pruning

From cuttings

Olea europaea can be propagated by taking semi-ripe cuttings

Semi ripe cuttings are taken from summer to mid-autumn (Jul-Sep) from healthy stems grown this season. The base of the cutting is firm, while the tip is still soft. Use for climbers, herbs, evergreen shrubs, conifers and hedging plants.

in late summer (July–August). Take cuttings

A method of growing new plants from parts of an existing plant, such as sections of root, stem, leaf or bud. When prepared correctly and planted in the right conditions, they can produce roots and eventually become independent plants. There is a wide range of different methods for taking cuttings, depending on the plant and time of year.

10–15cm long, remove lower leaves and place in sandy, peat-free compost

Can refer to either home-made garden compost or seed/potting compost: Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.

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Alternatively, in winter, take hardwood cuttings

Hardwood cuttings are taken from mid-autumn until late winter from vigorous healthy shoots of the current year's growth - this will be woody but pliable. Use for deciduous climbers, shrubs, trees (including fruit) and some evergreens such as hollies.

up to 30cm long from one- or two-year-old wood. Fill pots with sandy, peat-free cuttings compost and ideally provide bottom heat by placing the cuttings in a propagator

A propagator is a portable, lightweight structure usually plastic, with a vented or unvented lid to provide a humid, slightly warmer atmosphere. It is useful to help seeds germinate and root cuttings. It may have adjustable, thermostatic temperature control.

or on a heat mat. Mist the cuttings to keep the compost just damp, but not soggy, as excessive moisture can cause them to rot. Cuttings can root in a few weeks, but may take a few months. 

Named cultivars are best propagated by grafting

This involves joining the roots of one plant to the stem of another related plant, so they fuse together to form one plant. There are various methods, all requiring great skill. Grafting is mainly carried out by commercial growers to combine one plant’s qualities of flowering or fruiting (the upper section or scion) with the vigour or resilience of the other (the roots or rootstock). Fruit trees are often grafted, along with a few ornamental shrubs and trees, and in recent years grafted vegetable plants (mainly tomatoes, but also chillies, cucumbers, aubergines, etc) have become available.

, which is the preferred method in olive-growing regions. However, grafting olives can be difficult, so it is best suited to those who enjoy a challenge.

Cuttings: semi-ripe

Cuttings: hardwood

Grafting ornamental plants and fruit trees

From seed

Seed supplied widely in the UK is Olea europaea. Seed from named varieties may not come true to type and can produce plants with characteristics that differ from the parent plant.

Sow seed in spring. The hard seed coat needs washing and lightly abrading with sandpaper or a file. Next, either use a knife to nick the seed coat or soak the seed in warm water for 24 hours. Push seeds 2cm deep into moist, peat-free seed compost

Seed compost is a free-draining compost formulated for germinating seed. It often contains a mix of fine materials including sterilised loam, coir, coarse sand or grit. It contains low levels of nutrients, as high levels could damage seedlings.

with some added sand to aid drainage. Keep at 18–21°C on a warm windowsill or in a propagator. Seeds can take up to four months to germinate.

Trees and shrubs from seed

Olives are generally healthy when grown in suitable conditions but may be affected by the following problems:

• Xylella fastidiosa – olives are a high-risk host for this disease
• Olive scab
• Scale insects
• Frost damage – prune off affected, dead stems in late spring, cutting back to new shoots

Leaf loss or yellowing may be due to:

• Natural shedding of older leaves in spring as new growth begins
• Dry conditions, particularly when grown in containers. This can cause older leaves (usually lower or deep into the plant) to fall. When plants have been dry, you may also see brown edges to the leaves, prominently on the sunny side

If you are a member of the RHS, you can use our online Gardening Advice Service, via MyRHS, for any gardening problems or queries.