If you are growing semi-hardy or tropical trees in containers in a cold climate, this shows how to keep them safe during the winter and ready to grow again in spring.
For planting help, When is it too late to plant trees in fall? will get you started.
How to Overwinter Potted Trees
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The example I’m using here is a potted fig tree, but the steps are essentially the same for any deciduous tree growing in a container.
- Overwintering a potted fig tree is a simple process that requires a bit of work in the fall before first frost, and then again in the spring before last frost.
- You will need a winter storage space like a garage where (ideally) the temperature stays between 0-10°C / 32 to 50° F.
- Many fig trees are hardy (can survive year round outdoors) in gardening zones 7 to 11. With these overwintering tips, you can keep them thriving in zones as low as 4.
When I first got my fig trees (Chicago Hardy fig, 6″ long including the roots, by mail order) at the end of their first growing season, I could not find any information about how to protect them during the winter months.
Since then I’ve experimented and received advice and this is what works for me here in Ontario, Canada (zone 6).
- Overwintering tells the tree to nap for the winter, protected from freezing temperatures and light.
- When last frost approaches in the spring, you take steps to ‘wake it up’ again, to be ready for a new growing season.
- If you are growing your fig tree in a container, you’ll want to remove the tree from the container every second year and prune the roots. This keeps the tree healthy and encourages fruiting and growth.
Related: How to overwinter geraniums (as houseplants or in cold storage).
1Year One
In the fall, a few weeks before first frost
- Ease off on watering as the weather gets cooler and let the tree experience some dips in temperature including light frosts.
- Cooler temperatures makes the sap drop low in the tree and the leaves will yellow and start falling off (this is good).
- Right before storing the tree, spray it with dormant oil. This will kill off any pests.
- When frosts are near, move the container to a garage (ideal temperature range is 0-10°C / 32 to 50° F).
- Keep the plant in darkness (I put a big bag over mine).
- Some people don’t water them at all. I water mine very lightly every 6 weeks or so if the soil is really dry (a sign it needs new soil).
TIP: A base with wheels (plant trolley) makes this a lot easier!
In the spring, a few weeks before last frost
- Start watering the plant again and gradually reintroduce it to sunlight.
- Two weeks or so before last frost, place the tree outside, ideally in a warm spot. I put mine next to an exterior brick wall with southern exposure.
- If you’re still having frosty nights, bring the tree inside at night or cover it with heavy row covers or frost cloths.
- Within a few weeks you will see new growth, sprouts, and leaves.
Related: Cold Storage 101: Food Preservation Tips
2Year Two
Potted fig trees need ‘root pruning’ approximately every two years if they are growing well.
In the fall, a few weeks before first frost
- Remove the tree from the pot, and cut back approximately half the roots to a healthy ball.
- Wrap the root ball in a plastic bag and keep the tree in a cool dark place for the winter (ideal temperature range is 0-10°C / 32 to 50° F ).
- If you’re smart, you’ll have new potting soil, compost, and organic fertilizer all ready for re-potting in the spring.UPDATE: I have also repotted my trees right after fall root pruning and they did fine if done 6 weeks before garage storage so the roots could reestablish before winter dormancy.
A few weeks before last frost in the spring
- Re-pot the tree in fresh potting soil (2 parts soil-less mix to 1 part compost, plus granular organic fertilizer)
- Water lightly. Prune away any dead branches.
- Gradually reintroduce the tree to light.
- Two weeks or so before last frost, place the tree outside, ideally in a warm spot. I put mine next to an exterior brick wall with southern exposure.
- If you’re still having frosty nights, bring the tree inside at night or cover it with heavy row covers or frost cloths.
Within a few weeks you will see new growth, sprouts, and leaves.
Related: The Most Important Fall Garden Tasks.
3Year Three
Same as Year One. Root prune again in Year Four.
Insecticidal Soap
Before bringing plants indoors or storing them for the winter, it is wise to treat them with an insecticidal soap made specifically for this purpose.
Earth-tone Insecticidal Soap for organic gardening controls aphids, lace bugs, mites, grasshoppers, scale, earwigs, whiteflies and more.
I previously tried homemade recipes but since learned that products like dish soap are not effective for this purpose. A good commercial spray targets specific problems.
Frequently Asked Questions
1When should I bring my fig tree indoors?
When the leaves start to drop, it’s time to transition your tree to life indoors, or start preparing it for winter storage.
~Melissa the Empress of Dirt ♛
How to Overwinter Potted Trees in a Cold Climate
Supplies & Materials
- 1 Tree in a Container
Equipment
Instructions
Fall and Winter
- In the fall, a few weeks before first frost ease off watering and let the tree experience some dips in temperature including light frosts. Leaves should yellow and fall off.
- Right before storing the tree, spray it with dormant oil. This will kill off any pests.
- When frosts are near, move the container to a garage (ideal temperature range is 0-10°C / 32 to 50° F).
- Keep the plant in darkness (I put a big bag over mine).
- Some people don’t water them at all. I water mine very lightly every 6 weeks or so if the soil is really dry (a sign it needs new soil).
Spring
- A few weeks before last frost, start watering the plant again and gradually reintroduce it to sunlight.
- Two weeks or so before last frost, place the tree outside, ideally in a warm spot. I put mine next to an exterior brick wall with southern exposure.
- If you’re still having frosty nights, bring the tree inside at night or cover it with heavy row covers or frost cloths.
- Within a few weeks you will see new growth, sprouts, and leaves.
Notes
https://empressofdirt.net/what-is-overwintering/
Paul Guerette says
in the winter care of potted fig trees why do you insist on “Keep the plant in darkness (I put a big bag over mine).” I question the darkness requirement. I wish to keep mine in a heated shed with windows on east and south side where temperature will be held at 2 – 5 degrees C. Do i have to wrap them? If the trees were grown in the ground outside for the winter in zone 6 – 8 they would not require to be wrapped.
Melissa J. Will says
Hi Paul,
It’s really hard to compare a tree growing in the ground to one in the unnatural state of growing in a pot. Growing in nature offers lots of checks and balances that container gardening does not.
The pot has to be protected in our winters to avoid freezing the roots, which would otherwise be happy deep in the ground.
In winter storage, I slip a bag over mine because our garage has windows and gets drafty. Some winters it occasionally gets quite warm, triggering buds and leaves (if uncovered), which will then be lost when temperatures drop again. To prevent this, I encourage full dormancy.
I do not ‘wrap’ the trees though: I leave room for air flow just using a large loose bag. Depending on humidity in storage, wrapping could cause mold.
There are lots of ways to do this and choices will depend on your climate and storage space.
Good questions! I hope this helps.
Melissa J. Will says
Use these step by step instructions to protect any semi-hardy potted tree or shrub over the winter and reintroduce it to outside growing conditions in spring.