Common Olive Growing Mistakes in the UK and How to Avoid Them

Olive trees have a reputation for being tough, and on a sun-baked hillside in Greece or southern Spain they deserve it. Plant the same tree in a heavy clay border in Sheffield, water it like a tomato and leave it out in a wet January, and it will sulk, drop its leaves and quietly give up. The encouraging part is that almost every failure comes back to the same handful of mistakes — and each one is fixable, usually without spending much money.

Overwatering: the most common way to lose an olive

Olives evolved for dry summers and long, bright days. Their small, leathery, silver-backed leaves are built to hold on to water, not to shed it, and their roots dislike sitting in constant moisture. Soggy compost starves roots of oxygen, and the tree responds by yellowing, dropping leaves and looking desperately thirsty. The instinct is to reach for the can and water again, which only speeds up the decline.

Signs you are watering too much

• Compost that is still dark and damp 5cm below the surface days after you watered
• Leaves turning yellow, then dropping from the inside of the canopy outwards
• A sour, stagnant smell from the pot, often with a film of algae on the surface
• Soft, dark, mushy roots instead of firm, pale ones when you slide the tree out

The fix is simple to describe and harder to stick to: water thoroughly until it runs out of the drainage holes, then wait. Let the top few centimetres dry out before you water again. In a hot spell a pot may need a good soak twice a week; in a cool, grey week it may need nothing at all. Through winter, outdoor trees need no watering beyond rainfall, and a tree under cover needs only the occasional small drink to stop the root ball drying to dust.

An olive that dries out for a fortnight will usually forgive you. One that stays wet for a fortnight often will not.

Poor drainage, the wrong compost and the saucer trap

If you take one thing from this, make it this: olives need air around their roots as much as they need water. In heavy clay soil, digging a single planting hole simply creates a sump that fills with water in winter. Plant on a mound or in a raised bed instead, mixing grit and well-rotted organic matter into the backfill, and keep the soil around the trunk clear of weeds and grass.

In containers, the details matter more than most people expect:

1. Choose a pot with generous drainage holes — terracotta is ideal because it breathes.
2. Use a soil-based compost blended with roughly a quarter to a third horticultural grit or perlite.
3. Stand the pot on feet or bricks so water can escape underneath.
4. Skip the saucer, or empty it within the hour. A pot left standing in water is a slow execution.
5. Repot every two or three years into a pot only a size larger, ideally in spring.

Choosing a variety that suits a British climate

Not all olives are equally hardy, and garden centres rarely make the distinction clear. Varieties such as 'Leccino', 'Arbequina', 'Frantoio' and 'Pendolino' are commonly grown outdoors in the UK and cope with a British winter better than most. Tender, large-fruiting types such as 'Kalamata' are better treated as conservatory or very sheltered-wall plants.

Two other points worth knowing before you buy. First, olives are grown here mainly for their foliage and shape; a crop of fruit is a bonus, not a certainty, because our summers rarely give the heat and ripening season they need. Second, some cultivars crop more reliably with a compatible partner tree nearby, so if fruit matters to you, ask the nursery which pollinator suits the variety you are buying. Buy British-grown stock that has already spent a winter outdoors rather than a glossy imported specimen treated as a houseplant.

Winter protection: more than a bit of fleece

Cold alone rarely kills an olive in a sheltered UK garden. The combination of wet roots, freezing wind and a sudden sharp frost does the damage — and the root ball is far more vulnerable than the canopy. Work through the priorities in this order:

• Roots first. Wrap the pot in bubble wrap, hessian or an old blanket, and keep it off cold paving.
• Move it. A south or west-facing wall, an unheated porch or a cold greenhouse is ideal from late autumn.
• Keep it dry. Reduce watering to a minimum. A dry, cold root ball survives far better than a wet one.
• Fleece only when needed. Drape it over the canopy when a hard frost is forecast and remove it during mild days. Never wrap the tree in plastic.
• Do not bring it indoors. Warmth in a living room breaks dormancy, pushes out soft growth, and leaves the tree in a worse state by March.

Site, planting and the first year

An olive wants full sun for at least six hours a day and shelter from prevailing wind. Frost pockets — the bottom of a slope, a hollow, a north-facing corner — are the worst possible spot. Plant in spring or early summer so the roots have a full season to settle before winter, not in autumn. Water regularly through that first summer, stake for a year or two, and resist the urge to feed it hard.

Feeding and pruning mistakes

Feed lightly from spring to midsummer with a balanced or tomato-type feed, then stop by late summer so new growth ripens and hardens before the cold. Feeding into autumn produces soft, sappy shoots that frost kills outright.

Prune in late spring or early summer, once the risk of frost has passed. Autumn and winter pruning leaves wounds open in the coldest, wettest months. Take out dead, damaged and crossing branches and thin the centre so light and air reach the middle of the tree. Avoid cutting back into thick, old wood — olives regrow from it reluctantly. Little and often beats one drastic cut.

A simple routine that keeps UK olives alive

In spring, repot if needed, start feeding and prune after the last frost. In summer, water deeply but infrequently and let the surface dry between soakings. In autumn, stop feeding, cut the watering right back and move pots into shelter. In winter, wrap the pot, fleece the canopy during hard frosts, and otherwise leave the tree alone.

Get those habits right and an olive becomes the low-maintenance tree it is supposed to be: handsome, architectural and genuinely useful on a patio. If your only planting spot is heavy clay, an exposed ridge or a garden that sits in frost well into spring, it is worth a conversation with a specialist nursery or your local horticultural society before you commit, because the right site will matter more than anything you do afterwards.

Photo: valtercirillo / Pixabay