An olive tree in winter can usually stay outside in Ireland and the UK, as long as you keep two things in mind: how cold it gets and whether the tree is planted in the ground or growing in a pot. A mature olive tree in the ground can cope with short periods of light frost. An olive tree in a pot is more vulnerable, because the roots in the pot freeze more quickly than roots in the ground.
So the short answer is: protect a tree in a pot when the frost lasts longer or gets harder, wrap the crown up during a hard frost and keep its feet dry. If you have a young or small tree, or you expect a severe winter, overwintering it in a cool, bright spot indoors is the safest choice. Below you can read what to do in each situation, from wrapping the tree to watering it and the moment it can go back outside.
Is an olive tree hardy?
The olive tree (Olea europaea) comes from the Mediterranean. The winters there are mild, but it still freezes there at times. That makes the tree moderately hardy. Exactly how much frost an olive tree can take varies from source to source. A safe range is around -5 to -10 °C, depending on the variety, the age of the tree and how long the frost lasts. An old tree with a thick trunk survives a few cold nights better than a young tree with thin branches.
When it comes to whether olive trees are hardy, the lowest temperature is not the only thing that counts. These points also decide how well the tree gets through the winter:
- How long the frost lasts: one night of light frost is not the same as a week in which it freezes day and night.
- Wet soil: cold combined with water around the roots does more damage than dry cold. Roots that sit in wet, cold soil for a long time can start to rot.
- Wind: a cold easterly wind dries out the leaves. The tree then loses moisture that it cannot replace from frozen soil.
- Position: a spot against a south-facing wall or in a sheltered corner of the garden is a few degrees milder than an open, windy spot.
When you read that olive trees are hardy, this mainly applies to a mature tree planted in the ground in a sheltered spot. In every other situation, extra protection is a good idea.
Olive tree in a pot or in the ground
The biggest difference in winter is below ground. In the ground, the roots go deep and are protected by the soil around them. A pot holds only a limited amount of soil, and that soil cools down from every side. In a long spell of frost the whole root ball can freeze. The roots can then no longer take up water and get damaged, even if the crown itself can handle the cold.
A large pot with plenty of soil holds on to warmth for longer than a small pot. A tree such as the Olea europaea (olive tree) bonsai 270 cm tall, pot ø80 cm therefore has more of a buffer than a smaller specimen. Even so, large pots are also better insulated during a hard frost. A smaller tree, such as the Olea europaea (olive tree) standard 160 cm tall, pot ø24 cm, has little soil around its roots and is better off in a cool spot indoors during a hard frost.
Should you wrap an olive tree in winter?
That depends on the frost in the forecast. A few nights at a degree or two below zero are usually no problem for a healthy olive tree. If it is going to freeze harder or keep freezing for several days in a row, it is wise to wrap the tree up. For an olive tree in a pot this applies sooner than for a tree in the ground, because in a pot you also need to protect the roots.
Keep an eye on the weather forecast and wrap the tree up before the frost starts. A cover will not warm up a tree that has already frozen.
Olive tree winter protection: how to wrap it up
When you wrap an olive tree for winter, you protect three parts: the crown, the pot and the base of the pot. This is how to go about it.
The crown: an olive tree frost jacket or fleece
Use an olive tree frost protection jacket or a few layers of horticultural fleece (also called frost fleece or garden fleece). These materials let air and moisture through, but keep out the worst of the cold and wind. Pull the jacket over the crown and tie it loosely around the trunk at the bottom. Make sure the branches do not snap.
Do not use plastic. Plastic does not let moisture through. Condensation builds up underneath it, and that damp air leads to mould and rot. On sunny winter days it also warms up quickly under plastic and then cools down sharply again at night. Those swings are bad for the tree.
Insulating the pot
Wrap the pot in hessian, bubble wrap or a thick layer of fleece, or stand the pot in a larger container and fill the gap with straw or wood chips. Bubble wrap is fine here, because it goes around the outside of the pot and not around the plant itself. Also put a layer of straw, bark or leaves on top of the soil in the pot. This protects the upper roots.
Pot feet against wet roots
Stand the pot on pot feet, a few wooden battens or tiles, so it does not sit directly on the cold, wet ground. Excess water can then drain out of the holes in the base. A pot standing in a puddle freezes more quickly and increases the risk of root rot. Also remove any saucer from under the pot in winter.
A different spot for a while
If you can move the pot, put it against a wall of the house, out of the wind and under a roof or canopy. It is often a few degrees less cold there and less rain falls into the pot.
Unwrapping again
An olive tree is evergreen and still needs light in winter. So do not leave the cover on for months. During a spell without frost, take the cover off or open it up so light and air can reach the leaves. When frost returns, wrap the tree up again.
Overwintering an olive tree in a pot indoors
If you do not want to take any risks, or you have a young or smaller tree, you can overwinter the olive tree in its pot indoors. What matters is that the spot is cool and bright. A temperature of around 5 to 10 °C is ideal. Suitable spots include:
- an unheated conservatory or garden room;
- a greenhouse that stays frost-free;
- a bright garage or shed with a window;
- a cool stairwell or hallway with daylight.
Do not put an olive tree in a warm living room. In a warm room the tree wants to keep growing, but in winter there is too little light to do that properly. The result is weak, long shoots and often leaf drop. Dry, warm air also attracts pests such as spider mite and scale insects. A dark spot, such as a cellar without a window, is not a good idea either, because the tree will drop its leaves there.
Do not bring the tree inside too early. An olive tree can stay outside in autumn without any problem, even if there is the occasional light frost. Only move it indoors when a longer or harder frost is forecast.
Watering in winter
In winter an olive tree hardly grows and needs little water. Too much water is a bigger risk than too little during this period. Even so, the root ball must not dry out completely, because evergreen leaves still lose moisture.
- Outside in a pot: check now and then whether the soil is dry a few centimetres down. If so, give a little water on a day without frost. The winter rain is often enough.
- Overwintering indoors: give a small amount of water now and then, when the top few centimetres feel dry. Do not leave water standing in the saucer.
- In the ground: extra water is usually not needed. Only keep an eye on it during long dry, cold spells with a lot of wind.
Never water when the soil is frozen. The water cannot drain away and will freeze around the roots.
What to do after frost or leaf drop
If your olive tree loses leaves after a cold spell, or the leaves have turned brown or grey, the tree is not necessarily dead. An olive tree often drops part of its leaves when it is stressed and puts out new growth in spring. So do not start pruning straight away.
This is how to check whether a branch is still alive: scratch away a small piece of bark with your fingernail or a knife. If the wood underneath is green, the branch is still alive. If it is brown and dry, that part of the branch has died. Start at the top with the thin twigs and work your way down. Often only the tip is damaged.
Wait until spring to prune, when the risk of frost has passed and you can see where the tree is forming new buds. Then cut the dead parts back to just above healthy wood. After a hard winter, do not give the tree extra feed until it is visibly putting out new growth again. If you are unsure about what you see, you can enter your tree's symptoms in the Plant Doctor.
When to put it back outside
If you have overwintered the olive tree indoors, put it back outside once no more night frost is expected. When that is depends on where you live, so keep an eye on the forecast. If the spring is mild it can sometimes be earlier, but keep some fleece to hand for a cold night.
Let the tree get used to the outdoors gradually. After months indoors, the leaves are not used to bright sun and can scorch. Put it in partial shade for the first week and then move it to a sunny position. An olive tree is a sun-loving plant and grows best in summer in the warmest spot in your garden or on your patio. For a tree that has overwintered outside, remove the cover and the insulation as soon as the frost is over.
Which olive tree suits your situation
If you have room in the garden and a sheltered spot, you can choose a larger tree in a roomy pot. Think of the Olea europaea (olive tree) Cultivo 230 cm tall, pot ø45 cm or the Olea europaea (olive tree) Lorc 180 cm tall, pot ø50 cm. If you are looking for a broad shape for a patio, the Olea europaea bush 250 cm tall, pot ø55 cm is an option. Bear in mind that a large pot is not easy to move in winter, so choose a spot in advance where the tree can stay all year round or where you can wrap it up properly.
In our collection of olive trees in different sizes you will find trees for both gardens and patios. If you want to combine the olive tree with other plants that can stay outside, also take a look at the outdoor plants for garden and patio. If you are unsure which plant suits your spot, the plant finder will help you on your way.
With a good spot, dry feet and a breathable cover during a hard frost, an olive tree will get through most winters well. If you are choosing a new tree for your garden or patio, have a look at all our outdoor olive trees in our online shop.
Frequently asked questions
How much frost can an olive tree take?
A mature olive tree planted in the ground can cope with short periods of frost, roughly down to -5 to -10 °C, depending on the variety and age. Young trees and trees in pots are more vulnerable, because the roots in a pot freeze more quickly. Long spells of frost and wet soil make the damage worse.
Should you wrap an olive tree in winter?
For a few nights of light frost, wrapping is usually not needed. If it is going to freeze harder or for longer, cover the crown with a frost protection jacket or horticultural fleece and insulate the pot. Do not use plastic, because it traps condensation and causes mould.
Can an olive tree in a pot stay outside all winter?
It can, as long as you insulate the pot, raise the tree on pot feet and wrap it up during a hard frost. A sheltered spot against a wall also helps. With a small pot or a severe winter, a cool, bright spot indoors is safer.
Where should you overwinter an olive tree indoors?
In a cool, bright place of around 5 to 10 °C, such as an unheated conservatory, a frost-free greenhouse or a bright garage. A warm living room is not suitable, because the tree grows weak and leggy there and becomes prone to spider mite and scale insects.
My olive tree is losing leaves after a frost. Is it dead?
Not necessarily. An olive tree often drops leaves when it is stressed and puts out new growth in spring. Scratch away a little bark: green wood underneath means the branch is still alive. Only prune dead parts in spring.
When can an olive tree go back outside?
Put the tree back outside once no more night frost is expected. Let it get used to the outdoors for a week in partial shade first, so the leaves do not scorch in full sun.
