I have a few citrus trees including Kaffir lime, lime, tangerine, and lemon, and while they’re growing fairly well, I was wondering if any of them should be going dormant this winter. So, I did some research to find out more. Here’s what I found.
Citrus trees are evergreen and don’t go dormant in the winter because they’re natively from the tropics, which have little to no frost. Because of this, citrus trees had no need to develop a dormant state. If citrus trees lose their leaves during the winter, it’s likely due to improper weather, watering, or nutrients.
So, while citrus trees are from the tropics and don’t go dormant during the winter, why does this make them different than other fruit trees, and how can we best care for citrus trees during the winter? Let’s take a closer look.
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Why Citrus Trees Don’t Go Dormant
Citrus trees are evergreen trees, so they keep their leaves year-round. They’re native to subtropical and tropical regions of Asia and northeastern Australia. As a result, citrus didn’t need to adopt a state of dormancy and shed their leaves to survive the winters. They do best in USDA hardiness zones 9-11.
On the other hand, many other fruit trees are considered deciduous, or lose their leaves in the fall and winter. This is a survival technique that helps them reserve energy and persist through extreme cold. Think of a bear going into hibernation.
Common deciduous fruit trees include:
But, what happens if citrus trees are exposed to moderate-heavy frost?
Do Citrus Trees Lose Their Leaves in the Winter?
Since citrus trees are evergreen, they normally don’t go dormant or lose their leaves in the winter. If your citrus tree is losing its leaves in the winter, it’s likely stress related to weather, watering, or nutrients. Generally, citrus trees do best in USDA hardiness zones 9-11, or above 28ºF to 35ºF.
Reasons Why Citrus Trees Can Lose Their Leaves in the Winter
My potted Meyer lemon tree started losing leaves last winter and I wasn’t sure why. After some trial and error, I found that it was getting too cold outside. So, I moved it indoors.
However, it started losing even more leaves!
After more trial and error, I found that it was placed too close to the central heat and its leaves were drying out. I then moved it to another, cooler room of the house and it recovered nicely. It even started new growth!
Over or Under-Watering
Besides the weather, other common reasons why citrus trees lose their leaves are improper watering or a lack of nutrients.
Over and under-watering is fairly easy to do, but as a general rule: only water when the first 2-4 inches of soil are dry. This should be about once a week. Any more or less and the tree will either get wet feet or drought stress.
Lack of Nutrients
On the other hand, citrus trees will lose their leaves from a lack of nutrients. The best way to fertilize your citrus trees is with quality compost and mulch.
Compost not only provides nutrients but increases the soil’s richness. For example, every 1% increase in the soil’s richness can hold an additional 20,000 gallons of water per acre (source). It also provides nutrients to beneficial soil life such as earthworms and mycorrhizal fungi.
Mycorrhizal fungi promote many aspects of plant life, in particular improved nutrition, better growth, stress tolerance, and disease resistance.Department of Biology, University of Fribourg, Switzerland
Mulch dramatically reduces evaporation from the soil and protects it from erosion. One of the biggest threats to valuable topsoil is erosion. More specifically—after the sun has baked it, the wind and rain wash it away. This is why tilling is generally more harmful than beneficial.
In Gabe Brown’s book, Dirt to Soil, he showed how his farm in North Dakota underwent an extreme transformation once he stopped tilling and let livestock graze his land (much like how the buffalo grazed the Great Plains).
Other benefits of mulching include:
- Insulating the soil and tree’s roots
- Protecting beneficial soil life
- Breaking down into useable nutrients
Ideally, provide your citrus trees with compost every 1-2 months and a new layer of mulch every 3-6 months. Good mulches for citrus trees include leaves, bark, straw, pine needles, and grass clippings. Keep both mulch and compost at least 3 inches from the tree’s trunk to prevent mold or disease.
If you’d like to learn more about the best fertilizers for citrus trees, check out my recommended fertilizer page.
Tips To Care for Citrus Trees in the Winter
If you live in an area that gets light to moderate frost, and you’d like to help protect your citrus trees, here are some quick tips:
- Keep citrus trees above 28ºF-35ºF. The exact temperature depends on the variety, humidity, and wind chill. For example, I could tell the temperature was too cold for my potted Meyer lemon when its leaves started to look bruised. After moving it inside, the leaves thawed and turned bright green again.
- Move potted citrus trees indoors or into a greenhouse if temperatures get too cold.
- Insulate outdoor citrus trees with 1-2 feet of mulch and cover the canopy with bedsheets or a plastic tarp. Plastic is an especially good insulator and also keeps water and ice away from the tree. Tree trunks can also be insulated with cardboard.
- Plant citrus trees in a south-facing direction for maximum sunlight and warmth. Additionally, planting along a southern-facing wall will reflect sunlight and heat onto the tree, even into the night.
- Provide windbreaks if possible to reduce or eliminate wind chill. You can use walls or other trees.
How To Revive a Dying Citrus Tree
If you’ve tried all of the above, and your citrus tree is still declining in health, there are still a few things you can try.
To revive a dying citrus tree, the best and most effective method is to first identify the root of the problem. Once you know the issue you’re dealing with, you can take the necessary steps to address it. As long as you provide a solution fairly quickly, your citrus tree should survive.
Here are the most common growing issues that affect citrus trees:
- Over or Under-Watering
- Environmental Stress
- Lack of Nutrients
If you’d like to learn more about reviving your citrus tree, make sure to check out my post: 3 Quick Steps To Revive a Dying Citrus Tree.
Need More Help?
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- Local Cooperative Extension Services: While we do our best with these articles, sometimes knowledge from a local expert is needed! The USDA partnered with Universities to create these free agriculture extension services. Check out this list to see your local services.