With backyards getting tinier and tinier, growing fruit trees in containers can be a great space-saving option. But what do you do with your potted fruit trees when the temperatures drop? What if you don't have space to store them inside - and should you bring them in even if you do? Read on for the answers to these questions and learn exactly how to protect potted fruit trees through the winter so they are ready to thrive again next spring.
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You can grow just about any kind of fruit tree in a pot, which is great news for those of us who don't have a ton of garden space. Thanks to plant breeding, fruit trees are more compact, productive, and container-friendly than ever. But if you don't plan ahead, you may end up with too many potted trees and no way to keep them alive over the winter.
Some fruit trees can't tolerate cold at all and need to be brought into a heated space before the temperature drops too low. Others can tolerate some cold, but need to be protected from freezing. And still others can be left outside all year round, but only if winterized properly. So which ones need what type of care?
In this post I'll talk about which trees can or can't tolerate the cold, best practices for bringing fruit trees in the house for the winter, and how to protect those that will stay outside. I'll also discuss caring for potted fruit trees through the winter and how to transition them back outside in the spring. With the right care, fruit trees can happily grow and fruit in pots for many years!
Why Do Potted Fruit Trees Need Winter Protection?
Potted trees need even more winter protection than those planted in the ground. This is primarily because the root system is above the ground rather than in it. In winter, the ground may freeze and will stay cold even if the sun shines. But the soil temperature in a pot will fluctuate widely with exposure to sun, wind, and overnight cold temperatures.
In addition, because there is limited soil in the pot, there is far less soil insulating the tree's roots. Less insulation means the roots are easily damaged by cold, which weakens the tree. A tree with a weak root system will have trouble taking up nutrients and water from the soil, leaving it susceptible to further damage from cold, pests, or disease.
The job of the roots is to store up carbohydrates over the winter that can be converted to food once the temperatures warm up in spring. But if the sun shines on the pot and the soil temperature rises, the roots get "confused" and waste all that energy they've been storing up before the plant is awake enough to consume it.
How Cold is Too Cold for Potted Fruit Trees?
Every fruit tree can only tolerate cold down to a certain temperature before it suffers damage. This is where hardiness zones come in. Hardiness zones (also called growing zones) are designated by an area's average lowest temperature. For example, I am in zone 8b, which means the average coldest temperature where I live is between 15 and 20°F. Sometimes it gets colder than that, but that's the average low over a typical winter. (Find your hardiness zone here.)
Every fruit tree's plant tag (or online description) will indicate which growing zones it is suitable for. But when you are growing fruit in pots, treat the tree as if you are 1 or 2 zones colder than you actually are. This will tell you how likely that tree is to survive the winter in its pot above ground, exposed to fluctuating temperatures and wind. So I may live in zone 8b, but as far as my potted fruit trees are concerned, it's like I live in zone 6b or 7.
Tropical and subtropical fruit trees, including banana, mango, papaya, avocado, and citrus (among others) cannot tolerate cold well. These trees need to be brought inside or sheltered somewhere that protects them from the cold (see the next section for how to do this). Other fruit trees that are hardy to your zone in the ground could stay outside all winter, but they will need to be protected so the roots don't freeze. Even those that can tolerate cold well will have a better chance of survival with some protection.
Don't Forget Chill Hours
Wait! Before you carry all of your trees into the basement or garage, double check the tree's chill hour requirement. Most deciduous fruit trees (ones that lose their leaves during the winter) need a certain amount of cold time in order to bear fruit the following year. These trees need to go dormant and stay cold (but hopefully not freezing) over the winter. Apples, pears, and stone fruit trees like peaches, plums, cherries, and apricots must spend the winter somewhere unheated - with the temperature staying below 45°F.
Bringing Container Fruit Trees Inside During Winter
Cold-sensitive fruit trees, such as citrus or tropical fruits, need to be put somewhere that stays well above freezing. A tropical tree such as a mango might tolerate down to about 30-35°F in the ground, but in a container it needs to be sheltered when the temperatures dip below about 40-45°F. Many citrus trees can tolerate slightly colder temperatures (down to 25-30°F), but I protect mine once the nights drop below 40°F.
These warm-climate trees can be brought inside the house or into an insulated garage, shed, or basement. The key is bringing them somewhere that the temperature stays within the range the trees can tolerate. I bring mine into an insulated part of my garage, where the temperature rarely drops below about 40°F even on the coldest nights.
To avoid shocking the tree, move it to its winter location while the daytime temperature is still mild. Watch nighttime lows, and move potted trees as soon as it gets too cold for them to tolerate, even if it is still warm during the day. I have made the mistake in the past of moving a potted lemon tree inside after a few chilly days, and the tree went into shock and lost all its leaves. (R.I.P. lemon tree...)
Before bringing any pots inside, even into a garage, double check that there aren't any unwanted houseguests coming along - such as ants and other pests. To get rid of ants in potted fruit trees, I use an orange oil drench (I use this brand). The active ingredient in orange oil is D-Limonene, an insect-repelling chemical found naturally in citrus rind.
Watch the video below to see exactly how I rid my potted fruit trees of ants, as well as other methods of managing ants in the garden:
Once the trees are inside, pay attention to how much light and humidity they receive over the winter. Even tropical trees and citrus typically slow down their growth during the colder months, even if they don't go completely dormant. Because of this, they don't need as much light as when they are actively growing and fruiting. However, these trees still need some access to light in order to thrive. Likewise, it's a good idea to mist the trees with water every few days to replicate some of the humidity they normally expect.
When to Bring Trees Outside Again
Just like when you brought them in, watch nighttime temperatures to figure out when to move potted trees back outside. Wait until overnight lows stay above 40-45°F for a few nights - but don't immediately bring the trees out. First harden them off by bringing them outside, away from direct sun, for an hour or two a day. Gradually increase their exposure to the outdoors little by little over the course of a week (or more, depending on the weather). Once the tree has reacclimated to the fluctuating temperatures and sunlight, it's time to move it back to its outdoor home.
5 Ways to Protect Potted Fruit Trees Outdoors
Even fruit trees that are cold tolerant need some special care to make it through the winter. Read on for ways to keep fruit trees safe from cold damage outside. One of these ideas may be enough, but I recommend combining these methods for the best protection.
1. Move
Even if you aren't bringing them inside, it still is a good idea to move fruit trees to a more sheltered spot. Cold-tolerant trees can easily be damaged by the sunscald or winter wind. Bring deciduous potted fruit trees that can handle your average lows to a shady area out of wind and direct sunlight. Locations near a wall or fence may trap heat and block wind enough to make a milder microclimate. Or, move to an unheated garage or shed as long as the temperature inside doesn't drop too far below freezing.
2. Bury
Since trees in the ground are naturally more protected from the cold, try temporarily "planting" potted fruit trees. Dig a large hole and bury the root ball - pot and all - in the ground. Follow up with a thick layer of mulch to insulate the roots. Just as for in-ground trees, avoid planting too deep, and keep the mulch a few inches away from the trunk. Once the temperatures warm up again in spring, dig up the pot and move it back to its permanent location.
3. Insulate
In particular, insulate the roots. Use anything and everything to wrap the pot and trap warmth inside. A common way to do this is by setting up a cage of chicken wire around the pot, then filling the space between the cage and pot with straw or mulch to help insulate it. You can even use several layers bubble wrap or other material, securely wrapped around the root ball. The goal is to prevent the soil from freezing, and therefore prevent root damage.
4. Cover
A more extreme way to insulate a potted fruit tree is by covering it from top to bottom. Make a taller chicken wire cage around the entire tree and stuff it with lightweight material, such as shredded leaves, pine needles, straw, or mulch. Wrap the pot first for an extra layer of protection around the roots. You can then cover the whole cage with frost cloth for even more insurance.
Another way is to gently lay the potted tree on its side on the ground, then mound up straw or mulch over the tree to insulate it. Remove the coverings in late winter once the coldest temperatures have passed.
Group
Gather all of your container fruit trees in one area to make it easier to protect them. Group them somewhwere that keeps them out of the wind and direct sun, such as next to a house or building. Once the trees are all together, it will be easier to protect them in other ways as necessary.
One note about all of these methods - store your potted fruit trees directly on the ground, if possible, rather than on concrete. The temperature of the soil will stay more consistent, whereas concrete or other hardscaping will fluctuate. Wide temperature swings can cause problems for potted fruit trees, as mentioned above.
Caring for Potted Fruit Trees Through the Winter
- Water sparingly, but often enough to keep the soil lightly moist. Whether the trees are inside or outside, don't allow the root ball to completely dry out. The goal is to keep the tree from getting stressed throughout its winter holiday. It's better to water occasionally, but thoroughly, rather than shallowly and frequently.
- Periodically inspect the leaves and branches. For trees kept indoors, watch for pests like spider mites, or signs of stress like yellowing, droopy leaves. For bare outdoor trees, look for cold-damaged branches. Also watch for soil compaction, overly dry soil, or waterlogged soil.
- Hold of on pruning until the very end of winter, just before buds start to swell. Pruning leaves open wounds, which can easily lead to cold injury if the weather is too harsh. Also, pruning too early could signal the tree to begin growing too soon, especially if you have a spell of mild weather (as I often see happen here in zone 8b).
- Likewise, don't fertilize until the early spring. Container fruit trees must be fed regularly since they have limited access to nutrients in the soil. But avoid fertilizing over the winter, especially with nitrogen-heavy fertilizers, which can kickstart new growth. Wait until the tree shows signs of waking up in early spring before doing the first feed of the season.