Olive
Olea europaea
Silver-leaved evergreen of hot corners — rosemary and lavender at its feet.
- Type
- Fruit · Perennial
- Botanical family
- Mixed / other
- Foliage color
- Silver and gray · Green
- Flower color
- Purple and violet
- Sunlight
- Full sun
- Watering
- Low
- Soil
- Free-draining, moderately fertile
- Feeding
- Feed in spring, and give containers a liquid feed monthly.
- USDA zones
- 8a–11b
- Frost tolerant
- No
- Flowering
- May
- Pruning
- Thin it in late spring and take off the basal suckers.
- Overwintering
- Wrap it in frost cloth when hard frost is coming, and move containers under shelter for winter.
- Plant out
- at the last spring frost
- First harvest
- 180 days after the last spring frost
- Harvest ends
- 14 days after the first fall frost
- Mar–Mar Bud Break
- Mar–May Spring Growth
- May–May Flowering
- May–Oct Fruit Set
- Oct–Nov Harvest
- Nov–Dec Growing
- Jan–Mar Growing
- Plant spacing
- 9 ft 10 in
- In-row spacing
- 8 ft 2 in
- Between rows
- 13 ft 1 in
- Square-foot density
- Not suited to SFG
- Root system
- Woody, shallow and far-reaching
- Working depth
- 12–24 in
- Can reach
- 4 ft down where the soil allows
- Spread
- 26–39 ft across, about 2–3× the width of the plant
Almost all of a tree’s roots are in the top two feet of soil, where the air is, and they run out well past the branch tips. The deep taproot most people picture belongs to the seedling; the tree grows out of it and spends the rest of its life spreading sideways instead.
A wide, shallow plate of roots rather than a deep anchor, which is why an olive stands drought so well and wind so badly. It suckers at the base, and those suckers are how an ancient tree renews itself when the trunk finally goes.
The habit is Olive’s own; the figures are what that habit usually comes to at this size, not a measurement of this species. Roots follow the soil either way: a compacted pan, a high water table or heavy clay stops them well short of any of it, and deep open ground lets them go further.
- When
- Green (unripe) olives from September–October, black (fully ripe) from November into winter; realistically an outdoor crop only in warm dry climates (UK trees fruit reliably only in exceptional sites or under glass). Trees crop in 3–5 years.
- What to look for
- Green stage: full-sized, skin turned from bright to yellowish-green, flesh still firm — for firm brined olives. Ripe stage: skin fully purple-black with the flesh colored through when cut, and slightly soft — for oil and soft black cures. Critically, all olives are inedibly bitter raw (oleuropein) at every stage — never judge by taste off the tree.
- How to harvest
- Hand-strip ("milk") the branches into nets or aprons, or comb with a hand rake; pick before autumn storms drop the crop. Avoid bruising black-ripe fruit, which oxidizes fast.
- How often
- One pick per stage — a green-stage harvest, or leave the crop to blacken for one late harvest; a big tree may take two passes as ripening is uneven.
- Storing the crop
- Process within 1–3 days of picking — raw olives keep briefly refrigerated but must be cured before eating: water-cure, brine-cure (weeks to months), dry-salt-cure black olives, or lye-cure. Properly brined olives then keep a year or more in jars.
- Scale insects Immobile brown or white bumps fixed to stems and leaf undersides, sucking sap and weakening growth. Wipe off with a damp cloth or dab with horticultural soap; watch for the sooty mold that follows.
- Frost damage Soft new growth and open flowers blackened by late frosts. Fleece on cold nights, avoid planting in frost pockets, and resist cutting damage away until frosts pass.
- Olive moth
- Peacock spot
Beneficial predators that hunt this plant's pests — grow their favourite flowers nearby to recruit them. companion plant
- Hoverfly SyrphidaeHunts Scale insects
Bee-mimicking flies whose legless larvae graze aphid colonies clean while the adults pollinate. A ribbon of shallow, nectar-rich flowers kept in bloom all season recruits wave after wave of them.
- Ladybird (lady beetle) CoccinellidaeHunts Scale insects
The gardener’s favorite ally: adults and their alligator-shaped larvae each eat thousands of aphids, plus scale, mealybugs, and other soft-bodied sap-suckers. Grow flat, open flowers for the adults and never spray a colony that ladybird larvae are already working.
Lavender, Thyme, Rosemary
Good neighbors
Olive trees are astonishingly long-lived; some around the Mediterranean are over 2,000 years old.
Green-leaved fruit, like this one.
The Cottage Garden Companion — the gardener's herbarium at cottagegardencompanion.com