Olive tree care: sun, water and winter chill

Light

Give an olive the brightest spot in the house, and then some. NC State lists only full sun, meaning 6 or more hours of direct sunlight a day. On the Illinois Extension light scale, that is direct light of about 1,500 foot-candles, available indoors only directly in front of a south window. An east window offers a few hours of sun, a north window none, and an olive in either will slowly thin out, drop older leaves and push weak shoots toward the glass.

Summer outdoors solves the light problem for most of the year. The RHS advises waiting until all danger of frost has passed before moving a potted olive outside, then giving it a sunny, sheltered spot. After a winter behind glass, ease it into full sun over a week or two, as the Illinois Extension recommends for any houseplant going outside, so the leaves are not scorched. In winter, a sunny unheated porch or a cool south-facing room is far better than a dim corner of a warm room.

Water

Olives in the ground are famously drought tolerant once established, but a pot is a different world. The RHS advises keeping the compost moist through the growing season, and a 12 to 14 inch pot of gritty compost in summer sun can dry out quickly. Check with a finger: when the top inch is dry, water until it runs from the drainage holes. Raise the pot on feet, as the RHS suggests, so it never sits in a puddle.

Too much water is the more common way to lose a potted olive. UF/IFAS warns that excess water from irrigation or rain leaves olives susceptible to root rot and makes flowers drop before they form fruit. A dense, peat-heavy mix that stays wet for a week is the usual culprit, especially indoors in winter when the tree barely grows.

Our sources do not give a winter watering rule for a potted olive. In a cool, bright room the tree is close to resting, the gritty mix dries slowly, and checking the top inch before each watering is the safest habit. Do not let it go bone dry for weeks, though; an evergreen keeps losing some water through its leaves all winter.

Soil and pH

The RHS recommends pots of 12 to 14 inches (30 to 35 cm), or large enough for the roots to fit comfortably, filled with gritty, loam-based compost with some controlled-release fertilizer granules mixed in. Loam gives weight and stability to a top-heavy tree and holds nutrients better than peat. UF/IFAS adds that olives grow best in sandy, well-drained ground and actually thrive in poor soil. Add extra grit if your compost feels heavy, and make sure the pot has generous drainage holes.

Humidity

Humidity is the one thing an olive does not ask for. NC State describes it as a tree for hot, dry summers, and its leathery leaves are gray-green above with silvery, hairy undersides. The dry air of a heated home in winter, often below 30 percent according to the Illinois Extension, does not bother it. Skip misting; wet foliage in a cool room only invites fungal spots.

Temperature

The RHS says many olives are hardy, but branches can be damaged by severe frost, and pot-grown trees should be stored in a frost-free place over winter. UF/IFAS puts the danger line for trees in the ground at 20°F (-7°C). Roots in a pot are more exposed than roots in the soil, so bring a potted olive in, or into an unheated garage with a window, before freezing nights, and keep it above 32°F (0°C).

Warmth is not the goal in winter. NC State states that the olive requires 2 months of temperatures between 40 and 50°F (4 and 10°C) to flower. A sunroom, enclosed porch or cool spare room that stays in that band from December to February gives the tree its chill and keeps it alive. A heated living room at 70°F (21°C) keeps it alive, but usually without flowers or fruit.

Fertilizer

The RHS recommends a balanced liquid fertilizer every month through the growing season, which runs broadly from spring to fall, on top of the controlled-release granules mixed into the compost at potting time. Restraint pays off. UF/IFAS warns that excessive nitrogen produces lots of shoot growth at the expense of fruit, so avoid high-nitrogen lawn or foliage plant feeds. Stop feeding in winter while the tree is chilling.

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Repotting

Move an olive into a slightly larger pot in spring, the season the RHS recommends for planting, once roots are coming through the drainage holes or the tree wilts between normal waterings in summer. Use fresh gritty compost and set the tree at the same depth as before. When the tree has reached the largest pot you can move, keep it there and refresh the top couple of inches of compost each spring instead. Prune in early spring as well: the RHS suggests tip pruning the main branches back to a good replacement shoot each year to restrict a pot-grown olive's size.

• Roots grow through the drainage holes
• The soil mass is filled with roots
• The tree wilts between normal waterings in summer

Propagation

NC State lists seed and semi-ripe cuttings for the olive. Cuttings are the practical route, since they copy the parent tree and its fruit. Take a pencil-length piece of this year's shoot once its base has started to firm up in summer, strip the lower leaves, and root it in gritty mix with bottom warmth and humidity. Take several at once so that a few failures do not matter.

Methods: Semi-ripe cuttings, Seed · Best season: summer, when the current year's shoots are semi-ripe.

Common problems

Failure to bloom is the most common disappointment, and it is almost always the missing winter chill described by NC State. UF/IFAS adds that olives fruit on new growth, never in the same place on a stem twice, and tend to alternate heavy and light years, so a lighter crop after a big one is normal. Pests are few: NC State and UF/IFAS both single out scale insects, and NC State notes root rot, olive knot and verticillium wilt in the landscape. Indoors, weak leggy shoots in winter mean too little sun.

Not sure which one it is? Try the plant problem diagnosis tool →

Is the olive tree toxic to cats and dogs?

The olive tree does not appear on the ASPCA toxic and non-toxic plant lists for cats or dogs; we checked both, and the only olives listed there are the unrelated Russian olive and autumn olive. NC State's profile flags no poison hazard for Olea europaea either, and the fruit is a human food once cured. We therefore mark it as not rated rather than pet safe: absence from a list is not a formal safety rating, and no source we read has actually assessed it. Sweep up fallen fruit anyway, and call your veterinarian if a pet eats a large amount of any plant.

Check any other plant against the ASPCA lists →