Grow Potted Olives in Cold Climates

It was over two decades ago that I came home from a garden centre with a small potted olive tree. I was entranced by the shimmering light in olive groves in Italy—so when I saw that little plant here in Toronto, I grabbed it.

Olive trees are beautiful when the wind goes through them. The feathery leaves take on a silvery glow as they billow in a breeze.

My potted olive tree grew bigger and bigger. I shaped it into a nicely proportioned tree. When it sent up a sucker, I lopped off the sucker to make a second olive tree.

They were a beautiful touch of the Mediterranean in my cold-climate garden.

But those potted olive trees never gave me a single olive.

Not until I learned a couple of the simple but important things about potted olive trees that I share with you in this article.

A Bit About Olive Trees

I was entranced by the shimmering light in olive groves in Italy—so when I saw that little plant here in Toronto, I grabbed it.

Olives (Olea europaea) are long-lived plants that you can shape into a bush or a tree. In climates where they are winter-hardy, they can become small trees.

Gardeners in cold climates can grow olives in pots, where they do very well. They make fine potted patio plants because they are tough as nails.

Young branches with small, leathery, silvery-grey leaves move in the breeze, so if you’re next to an olive tree on a breezy day there is a beautiful shimmering light.

(If you want to add silvery-grey tones to the garden, artichoke and cardoon have silvery-grey leaves too.)

Potted Olive Tree Summer Care

Olive trees do best with lots of sunlight. This potted olive tree is growing beside my deck.

If it’s an option, put your potted olive tree outside for the summer. Olive trees do best with lots of sunlight.

(They look very nice amongst potted lemon trees ! Find out how to grow figs in pots.)

The quality of light indoors, even near a bright window, is not as good as outdoors.

Potted Olive Tree Winter Location

There are a number of ways to keep potted olive trees over the winter. Over the years, my mine have spent the winter in a number of settings:

Minimally heated sunroom
Insulated garage (kept just above freezing)
A cool greenhouse
My dining room

(When they were in the dining room, we put lights and decorations on the for Christmas!)

If you have somewhere cool and bright, such as a sunroom, that’s my recommendation. A temperature range of 5-10°C (41-50°F) is ideal.

Olives do tolerably well indoors, in centrally heated homes...but it’s not ideal. The warm, dry conditions indoors are less than ideal for your olive tree.

Those warm, dry conditions in the house are:

Not conducive to flowering
Great for insect pests such as scale

But if the house is your only option, you can make it work. Choose a location with a bright window, or put the olive tree under grow lights.

The trench method is another way to keep an olive tree over the winter in a cold climate. Dig a trench, lay the olive tree in the trench, and then mulch heavily. The depth of the trench and amount of mulch you need will depend on where you are.

You can also lay over fig trees for winter. Find out how.

While in-ground trees are said to withstand -10°C (14°F), don’t expose your potted olive tree to more than a light freeze. (See notes on hardiness, below.) That’s because the root temperature of in-ground trees is moderated by the soil (the soil temperature doesn’t swing back and forth like the air temperature). The roots of potted plants are subject to air temperature fluctuations.

Find Out How to Grow Your Own Figs

Harvest more figs this year! Grow Figs in Cold Climates Masterclass shows you how to grow a fig tree in a pot, or outside with protection. So you can harvest lots of figs!

How to get Potted Olive Trees to Flower and Fruit

This potted olive tree is budded up and ready to flower. Without a cool spell, the flowering cycle of the tree can be disrupted.

As I mentioned, while olive trees survive in a centrally heated home, growing indoors at room temperature is not ideal.

Pests aside, the main reason is that with warm conditions over the winter, your olive tree might not gear up to flower. That’s because olive trees need “winter chill” to induce flowering. It just means that the plant makes flower buds in response to cool temperatures.

Without a cool spell, the flowering cycle of the tree can be disrupted. (Some people refer to this period of cold temperature as “chill hours.”)

My original two olive trees—clones from the same plant—looked great but didn’t fruit for years when I kept them over the winter in warm conditions. When I tweaked my overwintering technique to give them cool temperatures over the winter in a sunroom that almost hit the freezing mark on cold nights, they bloomed. They were covered in blooms!

So keep in mind that if you overwinter olive trees at room temperature, you might not get flowers.

And no flowers means no olives.

Pollination

Olive flowers. When your olive tree blooms, expect lots of pollen. It’s everywhere.

Olive trees are not reliably self-fertile. That means that some olive varieties require a second plant of a different variety for successful pollination.

Even if you have an olive variety that is self-fertile, crops can be larger if there is cross-pollination with another variety.

When your olive tree blooms, expect lots of pollen. It’s everywhere.

That yellow dusting of pollen is normal because olives are wind-pollinated. If you want to help the process of pollination, you can use a feather duster, or a vacuum set on reverse to blow. (I let nature take its course, and don’t help with the pollination of my olive trees.)

When to Harvest Olives

Harvest time depends on the growing season, the variety, and stage of ripeness.

Olives can be picked at different stages of ripeness:

Green (wait until the juice inside goes from clear to milky)
As they start to develop colour
When fully coloured (the longer you leave the olives, the more colour they will develop—and the final colour depends on the variety)

Care for Olive Trees in Pots

Soil

For small plants, where I’m repotting every year, I use a soilless mix.

For my full-size olive trees, which I repot every 3-4 years, I use a loam-based potting soil such as a John Innes mix. The soil portion of this sort of potting mix is stable in the long term. I like the combination of moisture retention and weight that the soil provides. (Weight is important so that the trees do not tip over in the wind.)

Water

Just because olive trees tolerate dry conditions doesn’t mean that you can skip watering!

Keep potted plants well watered, but not constantly wet. If that sounds like a contradiction to you, it just means let the soil get dryish—on the dry side of moist—before you water again.

Don’t let the bottom of the pot stand in water; for example, keeping it in a low spot where water collects after rain, or keeping a saucer under the pot. Olive trees don’t like to have “wet feet.”

Feeding

Feed your potted olive tree with an all-purpose fertilizer that has micronutrients in spring and summer. Stop fertilizing over the fall and winter.

Potted Olive Tree Autumn Care

There’s no rush to bring olive trees indoors in the fall. I leave mine out even as we get light frosts.

As you get them ready to bring indoors, check for pests. Scale is the most common pest of potted olive trees indoors.

Find Out How to Grow Your Own Lemons

Harvest more lemons this year. Grow Lemons in Cold Climates Masterclass shows you how to grow a lemon tree in a pot or outside with protection. And get lemons!

Pruning Potted Olive Trees

Shape a Young Olive Tree

Scale is the most common pest of potted olive trees indoors.

(Formative Pruning for a Young Olive Tree)

A young tree might need support until its stem thickens. Tie it loosely to a stake. As the trunk thickens, you can remove the stake.

Plants that are grown from cuttings (as are most commercially available plants) are “physiologically” mature and can fruit while quite small. Twelve-inch trees might start to flower and fruit (teenage olive plants thinking they’re adults!)

Resist the temptation to let the fruit develop: While the plants are this small, you want to encourage stem growth. Fruit will slow down stem growth. Remove fruit from small trees and focus on building a permanent framework of branches.

If you’re developing your young olive plant into a tree, at a certain height you will want “scaffold” branches – like arms coming out horizontally from your main trunk. Aim for 3-5 scaffold branches. If you want your olive tree to be about as tall as a person, allowing these to form at about 3’ from the ground is a good starting point.

The size of potted plants is determined by the gardener. I prune the plants to six feet in height so they are easily carried through a doorway. Once the tree has reached the biggest size you can deal with, think of it like a big bonsai – and keep it at that size.

Grow Lemons Where You Think You Can't

Young plants can be set back by heavy pruning, so, unless necessary, keep pruning of young potted olive trees to a minimum.

Maintenance Pruning for Established Plants

The first thing to keep in mind as you prune your olive tree is that fruit forms on growth from the previous season. So if you give the tree a haircut all around and prune off new wood, you won’t get much fruit.
The second thing about olive pruning is that the plants have a growth habit which, after you develop and eye for it, actually makes them simple to prune. Branches bend under their own weight, sagging more and more as time goes on.

As the branch gets longer and the end sags, there are new branches growing upwards from it, closer to the centre of the tree. Prune off the sagging end of the branch, leaving these replacement branches. The new growth on these replacement branches gives olives.

Prune off the sagging end of the branch in the fall. This leaves the branches above as replacement branches.

Here are things to keep in mind as you prune your olive tree:

Prune to the size and shape you want
Remove crossing branches
Remove branches growing inwards, towards the centre of the bush or tree
Remove suckers that grow from the base of the plant
Remove vigorous shoots growing upwards as these are not usually very fruitful

Rejuvenation Pruning

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Olive trees have an amazing ability to make new shoots from old parts of the plant. This means that if you have a tree or bush that is very overgrown, you can prune heavily, right back to major branches, and still have replacement branches grow.

When you make a major pruning like this, the response of the plant will be to send up lots and lots of new shoots.

Here’s the trick: Don’t leave all those new shoots until you prune the following year. Letting them all grow will let the plant waste lots of energy. Only leave the ones that you want—and snip off the rest.

One other thing if you’re renovating an older tree: Avoid tearing the bark as you cut and remove bigger branches. You don’t want to leave a little bit of bark attached, and then, as you pull away the pruned branch, tear a strip of bark from your tree.

When to Prune Olive Trees

I do the main pruning on my potted olive trees in the fall, before moving them into winter storage. My winter storage conditions are quite moderate…and I need to keep trees on the small size for my small storage space

Potting and Repotting Olive Trees

Repot olive trees in the late winter or spring, just before new growth begins.

Your choice of final pot size depends on how large you want your olive trees to grow. My own olive trees are in pots that are 36 cm (14”) wide — and that’s big enough for the two-metre-high trees (6’ high). Because you’re moving the trees around spring and fall, select a size that isn’t too heavy for you.

When you’re getting started with a small olive plant, like the little one I originally brought home from the garden centre, move it to a slightly bigger pot each spring.

Larger trees do not need to be repotted every year. In years that you don’t repot them, top up the potting soil with some fresh potting soil and compost.

I’ve seen fantastic specimens in half-barrel sized pots…but that’s too big for my setup.

Olive Varieties

My original two olive trees are an unnamed variety with olives that are large, plump, and green when I pick them here in Toronto in October.

There are many olive varieties. They differ in the size, shape, flavour, texture, colour, and oil content of the olives. The winter chill requirements also vary.

Different varieties also have different amounts of cold tolerance. While cold tolerance is important for in-ground olive cultivation in borderline zones, it’s not an issue for potted olives that are moved to a protected space over the winter.

My original two olive trees are an unnamed variety with olives that are large, plump, and green when I pick them here in Toronto in October. My third olive is a self-fertile variety called ‘Frantoio.’ It has smaller olives that are just starting to colour up as I pick before putting away my olives for winter.

Olive Tree Hardiness

Hardiness is never an exact science. It varies by variety; and is affected by the timing of the cold, the duration, and if there are large temperature swings.

The fruit can’t withstand temperatures as cold as the tree.

Different sources give different minimum temperatures. The key thing to keep in mind with a potted olive tree is that potted trees can’t take as much cold as in-ground plants.

So forget the exact numbers and just play it safe.

I use -2°C (28°F) as a safe minimum temperature for my potted olive trees. (I’m sure some gardeners have had potted olive trees survive temperatures colder than this — but there’s no need to take a chance if you’re going to all the trouble of growing a plant in a pot.)

If your olive tree is exposed to temperatures that are too cold, you will see damage to leaf and branch tips, and newer leaves that are around the outside of the tree canopy.

Are you in a borderline hardiness zone and wondering whether there’s a way to grow olive trees in the ground? Read this article about growing olives outdoors in Canada.

If you’re interested in the things that affect hardiness, here’s a post where I talk more about them and how they affect fig hardiness.

Potted Olive Trees in Landscape Design

Potted olive trees have great ornamental potential. One use is as a focal point.

If you’ve read this far and are thinking it’s a bit of a bother to grow a potted olive tree in a cold climate, aside from the olives, there’s one other thing to consider: The ornamental value of potted olive trees.

Here are some ideas:

Potted olive trees on either side of an entrance to frame it
Potted olive trees as a visual screen beside a sitting area
A potted olive tree as a focal point in a formal edible garden or potager
An exotic interest plant on a deck or patio (looks great next to a potted lemon tree!)

Olive Tree Propagation

The easiest way for a home gardener to propagate olive trees is to look for a sucker coming up from the base of the plant, at soil level. If you’re lucky, that sucker will have some of its own roots – and you can cut it from the plant and pot it up. (You might need secateurs or a saw.)

Nurseries propagate olives from cuttings. Olive cuttings don’t root as easily as some plants. But if you would like to try, get a cutting with a few nodes, 8-12” long. Use rooting hormone, and keep it in humid conditions. Keep humidity high by covering individual pots with clear plastic bag; or, if it’s a whole tray, with a clear dome.

Find out how I propagate fig trees from cuttings.

Potted Olive FAQ

The easiest way for a home gardener to propagate olive trees is to look for a sucker coming up from the base of the plant. I removed this sucker, along with roots, using a pair of secateurs.

Why does my olive only have fruit every second year?

This is called “alternate bearing” and is common with many fruiting plants. Apples are a good example. The tree uses lots of energy to develop a big crop, so no energy is used to make flower buds for the following year. This is solved by pruning and fruit thinning. If you prune your potted olive every year, you can minimize alternate bearing.

When should I bring my olive tree indoors?

It’s not an exact science. I leave my olive trees outdoors for a couple of weeks of temperatures near freezing before moving them to a protected space. This helps to satisfy winter chill requirements.

Can you grow an olive tree from a pit?

Yes. My neighbour Joe had a seed-grown olive tree that he liked to show me. If you enjoy the challenge of growing from seed, try it. But know that, like apples, olive seeds won’t give you a plant like the parent plant. If you want an olive with known properties, start with a cutting or a graft from a known variety.

Can I grow an olive tree in Canada?

Yes! Read about olive trees in Canada. In warmer areas they can grow in the ground (with or without protection, depending on the conditions—and in colder zones, in a pot.

Why can't you eat olives off the tree?

You can do it once, but I guarantee that you won’t try it a second time.

Fresh olives contain alkaloid compounds that make them jarringly bitter. You’ll contort your face and say something rude. And then know better next time.

How do you brine an olive?

I just slit olives lengthwise with a knife as I prepare them for brining.

There is more than one way to do this. The goal is to remove the bitterness.

Here’s what I do, thanks to the guidance from friends from olive-growing regions:

First, break the skin so that the brine can better penetrate the olive. Some people crush the olive with a mallet or the end of a knife handle, and some people prick them with a fork. I just slit them lengthwise with a knife.
Then I put the olives in a jar or bowl of water to soak for 10 days, changing the water twice a day.
After that the olives go into a brine of 100 grams of salt per litre of water.
Leave the olives in the bring for at least 2 weeks, probably longer. Taste one, and if it’s too bitter for your liking, brine the olives longer.
When I think they’re ready, I put pour off the brine, and then marinate them with red wine vinegar, lemon zest and juice, a bit of olive oil, crushed garlic, rosemary, and ground pepper.