Winterizing your olive trees and protecting them from the cold

Shedding about a third of its leaves over the dormant period is perfectly normal for an olive tree, which stays hardy down to 10 to 17°F (-8 to -12°C) when the cold arrives gradually and the air is dry. Damp, not frost, is the killer: divert water, mulch the base and wrap the branches, and the tree comes through.

If the cold sets in gradually and the air is dry, olive trees are hardy down to 10 to 17°F (-8 to -12°C). Some have been known to survive temperatures as low as 0 to 4°F (-15 to -18°C). When moisture and water join the game, all is lost.

Olive hardiness zone UK: H2-H3
Olive hardiness zone USA: 9b-10
Hardiest olive tree varieties: Arbequina, Picholine and Mission

• What freezing does to an olive tree
• Why olive trees need cold weather

Winterizing your olive trees and protecting them from the cold at a glance

Name	Olea europaea
Family	Oleaceae
Height	up to 50 feet (15 meters)
Soil	light, stony, very well drained, never soggy
Foliage	evergreen

Protecting olive trees in winter

The basic rules to protect your olive tree from the cold in winter are:

• excellent drainage (no soggy soil)
• shelter from wind (windbreakers)
• fleece or bubble wrap (insulation from the cold)
• moving the tree indoors if too cold (for potted olive)

You’ll have to proceed differently depending on whether your olive grows in the ground (see right below) or in a pot/container (jump to it here).

• Wrap with breathable horticultural fleece or hessian, never plastic sheeting.
• On mild, dry spells, open or lift the wrapping so air moves through the crown and the leaves do not start to rot.
• Hold off on pruning an olive until all risk of frost has passed, because fresh cuts and the soft shoots they trigger are the first tissue the cold destroys.
• Gently knock heavy snow off olive branches, because their evergreen canopy catches and holds weight, and overloaded limbs can bend, split, or tear away at narrow forks.

Winterizing an olive tree in the ground

If you live wherever winters are mild, with only light frost, you shouldn’t worry, your olive trees will certainly survive. However, if you live North or in a region where it rains a lot during winter, you must take a few steps to protect your olive trees.

Drainage:

It is important to evacuate water as far as possible from your olive trees in winter: nothing is more dangerous to your tree.

• With soil, create a mound around each tree so water doesn’t flow towards the trunk.
• Stop irrigating after the harvest.
• Don’t fertilize after the harvest. Specifically, don’t add nitrogen-rich fertilizer in fall or autumn.

In spring, after freezing is over, start irrigating or watering again. This will help your olive trees recover from wounds due to frost.

Shelter:

Growing your olive trees in front of a wall or hedge will cut off the coldest winds. If some portions of your orchard are exposed to cold wind, set up a windbreaker. Even a low stone wall will work wonders and is better than nothing.

Insulation:

Mulch the base around the olive trees to protect roots from freezing.

Use organic plant-based mulch: it breaks down and fertilizes soil only towards the end of winter. Before that, it’s a great insulator.

Wrap the tree with insulation. On smaller trees, a wide swath of bubble-wrap or winterizing fleece helps survive over the first few years. A fully-organic option is burlap or bundles of straw.

Once wrapping the tree becomes impractical, let the tree fend for itself, or wrap just the trunk and scaffold branches. Older trees resist cold weather better than younger ones. In fact, cold weather improves olive-bearing, to a certain point.

Olive varieties compared: hardiness, habit and use

Not every olive faces a cold, wet winter equally well, and habit matters just as much when the tree has to be wrapped or moved under cover. The table below sets out the cultivars most often sold in British and North American nurseries.

Olive tree in a pot: winter care

Once again, if you live in warm areas, where temperatures never drop below 20°F (-6 or -7°C), not much is needed.

• Place your potted olive tree in the sun, near a wall.
• Water only if the soil is completely dry, and then only small amounts of water.
• It’s normal for the tree to lose some of its leaves over the dormant period, about 1/3^rd of them will fall in winter.

However, if you live further North, and the weather is colder:

• Move your olive tree indoors to a cool and well-lit place where it never freezes. Garage, unheated greenhouse, garden shed…
• Protect your olive trees from excess soil moisture by not watering much.

If you cannot bring your potted olive trees indoors,

• Never bring your olive trees indoors in winter. Giving it only a couple days of warmth would trigger growth. This is uncalled for in the middle of winter.
• Outside, bring them as close as possible to a window so they can benefit from the warmth of the house.
• Mulch the base of your olive trees to protect them from the cold.

Lastly, wrap the olive tree as follows:

• Wrap the pot with a thick cover or straw, and block rain from trickling in.
• Cover all branches with horticultural fleece, keeping buffer space all around so leaves don’t touch it. The goal here is to avoid condensation touching the plant since it is a source of moisture. Pack straw around the branches if need be.
• Water as little as possible, and only if no rainfall reaches the plant.

Read also:

• All about the olive tree and its fruits

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