An Olive Tree Is More Possible Than You Think

Olives have been grown in British gardens for centuries, mostly as handsome evergreens rather than cropping trees, and that is still the sensible way to approach them. An established olive will shrug off a normal English winter, particularly if it is a hardy cultivar in a sheltered spot, but it will sulk, drop its leaves and sometimes die if its roots sit in cold, soggy soil from November to March. Cold is rarely the killer here; winter wet is. Get the drainage right, choose your position with care, and you have a genuine chance of picking your own fruit in a good summer.

Choosing a Spot and a Cultivar

Find the sunniest, most sheltered place you have. A south or south-west facing wall, a fence, or a warm corner of a patio is ideal, with at least six hours of direct sun in summer. Avoid frost pockets at the bottom of a slope and exposed spots where cold east winds strip the leaves.

Cultivars worth asking for at a good nursery include:

• 'Arbequina' — compact, self-fertile and one of the best for a British garden, happy in a large pot.
• 'Leccino' — tough, upright and reliable, with good cold tolerance.
• 'Frantoio' — vigorous and generous, a useful pollinator for others.
• 'Picual' — hardier than many, though it needs warmth to crop well.

If you have room for two, plant them within a few metres of each other. Cross-pollination noticeably improves the crop, even with cultivars described as self-fertile.

Planting, Compost and Drainage

In the ground, plant in late April or May so the roots have the whole growing season to settle before winter. Dig a hole twice the width of the rootball and fork the base to break up any pan. Mix the backfill with plenty of grit, horticultural sand and well-rotted compost, aiming for something that feels crumbly rather than sticky. Plant on a slight mound so the crown sits a few centimetres above the surrounding soil, and never bury the trunk below its original soil line. Firm gently, water well, and stake for the first two years.

Mulch with gravel or coarse bark, keeping it clear of the trunk. A raised bed or a slope is far better than a heavy clay border; if your soil is clay, plant in a pot instead.

For containers, use a pot at least 45–50cm across, in terracotta or a heavy frost-proof material so it does not blow over. Stand it on feet or bricks so water drains freely, put crocks or a layer of gravel in the base, and fill with a loam-based compost such as John Innes No. 3 mixed with about a third grit by volume.

Watering, Feeding and Winter Care

Water new trees deeply once a week through the first two summers, and keep potted olives watered regularly from spring to early autumn — they are drought tolerant once established, but not while they are settling in. Feed with a balanced fertiliser in spring, then switch to a high-potash tomato feed from midsummer to encourage flowering and fruit set.

Winter is where most British olives are lost, so plan for it:

• Move pots against a house wall or into an unheated greenhouse or porch for the worst of the weather.
• Wrap the pot, not the foliage, in bubble wrap or hessian to stop the rootball freezing solid.
• Throw fleece over young trees on frosty nights, and remove it in the morning.
• Keep rain off the compost if you can — a sheet of clear plastic over the pot, removed on mild days, is often enough.
• Do not water in winter unless the compost is bone dry, and never let the tree stand in a saucer of water.

Pruning and Shaping

Prune in late spring, once the risk of hard frost has passed — usually mid-May. Olives fruit on the previous year's growth, so aim to build an open, goblet-shaped framework that lets light and air into the centre. Remove dead, damaged and crossing branches first, then thin out congested growth and shorten long shoots by about a third. Little and often beats a hard chop. Avoid autumn pruning, as the wounds heal slowly in cold weather and leave the tree open to disease.

Flowers, Fruit and Curing Your Own Olives

Tiny creamy-white flowers appear in June and July, carried on the current season's growth and pollinated by wind rather than insects. The fruit swells through late summer, turning from green to purple and finally black through autumn. In most British gardens the fruit will not ripen fully before the cold arrives, so pick it green in October, when it is still firm, and cure it yourself.

Raw olives are intensely bitter and must be treated. Slit each one or crack it lightly with a rolling pin, soak in cold water for ten to fourteen days, changing the water daily, then pack into a brine of about 100g salt per litre of water and leave for six to eight weeks. Alternatively, layer green olives with dry salt in a jar, shaking daily and pouring off the liquid that forms. Either way, you will have something far better than anything on a supermarket shelf.

Do not expect to press your own oil — that takes kilos of fruit and a great deal of patience — but a bowl of home-cured olives, a glass of something cold and a tree that has quietly survived another British winter is a fine reward in itself.