It’s currently fall here in Austin, Texas, and I’m keeping a close eye on the temperature as winter approaches. Even though my potted lemon tree is young, I’d like to prevent any frost damage if possible. But what happens during the holidays when I leave town for a couple of weeks? Will my lemon tree die if I leave it outside in the winter cold? To help keep my tree alive, I did some research.
If your winter temperatures drop below 45ºF, you should bring your potted lemon tree inside. While the tree may not die at this temperature, if it reaches around 30ºF, it can be permanently stunted. The longer the tree stays at this temperature, the higher the likelihood it will die.
But what happens if you have to leave the tree outside? Also, if you bring it inside, can you expect its leaves to drop from the lack of sunlight? I had the same questions. Let’s take a look.
What’s the Lowest Temperature a Lemon Tree Can Handle?
If you have to leave your potted lemon tree outside, or if your indoor temperatures can get pretty cold, how low of a temperature can it take?
A lemon tree can handle temperature down to 45°F, but if temperatures start to get closer to 32°F, you may want to bring it inside. If it’s planted outside, try covering it with sheets or tarps. Mulching and insulating the root-base can help reduce frost damage.
Potted lemon trees are fairly cold-resistant, especially if they’re grafted from a hardy rootstock, but even they have their limits. There are several ways you can help keep your tree warm during winter, so keep experimenting and see what works best for you and your tree.
For more information, check out my other article about what exact temperature to bring your lemon tree inside.
How Do You Take Care of a Potted Lemon Tree in the Winter?
Whether you decide to keep your potted lemon tree inside or outside this winter, there are a few key necessities it will need to survive.
You can keep your potted lemon tree warm in the winter by placing it near a window, or an area of the house that doesn’t get freezing temperatures. Keep an eye on the first 2-3 inches of soil and water it if it gets dry. Hold off on fertilizer until spring, when the tree is back outside and growing.
If you decide to place your lemon tree near a window, choose a southern-facing window if you have one. It will get a good amount of sunlight this way.
When your potted lemon tree is inside the house, make sure you avoid placing it near any heating units or vents. These can quickly overheat and dry out the lemon tree. A good temperature to aim for is 55-70ºF. If you believe your house is too hot, try placing it near a window or in the garage (since they’re both less insulated and allow some cold in). Just make sure the garage isn’t too cold.
Keep an eye on the top 2-3 inches of soil, and only water when it gets dry. If it’s still wet after you last watered it from a week ago, you may need to improve the drainage by reconstituting the soil with a more porous material (like peat moss or sand) or drilling more holes in the base. Lastly, you should avoid fertilizing your lemon tree in the winter as it’s not actively growing and doesn’t require the extra nutrients. If there’s too much fertilizer in the pot, the high-nitrogen content from the synthetic fertilizer could burn the tree’s roots.
If you decide to keep your potted lemon tree outside instead, you can either put it next to a wall that gets a lot of sun or cover the tree with sheets or tarps. Insulating the pot with cardboard or other insulating materials can also help keep the tree alive and warm. Your goal should be to not let the rootball freeze.
For more information about caring for lemon trees, make sure to check out my recent post: Lemon Tree Care: The Complete Guide (Indoor & Outdoor).
Do Potted Lemon Trees Lose Their Leaves in Winter?
Sometimes, lemon trees can develop some issues in winter. Diseases, rotting, or leaf loss can sometimes happen. The good news is that how you care for the tree has a direct impact on how well it survives the winter. So, why do some lemon trees lose their leaves in the winter?
Lemon trees don’t lose many leaves in the winter unless they get Winter Leaf Drop (WLD). WLD occurs when the leaves of the tree get much hotter than the roots. If the roots are too cold and dormant to help cool the leaves down, the leaves will fall off. WLD mainly occurs when lemon trees are indoors.
When indoor lemon trees are next to a window that gets a lot of sun, it can usually benefit the plant. Unfortunately, it can also hurt it. If the sun is strong enough, the leaves can get up to 100ºF, while the roots stay around 50-60ºF. The roots are unable to send moisture up to the leaves to cool them off, so the tree’s natural response is to shed the leaves (even when they’re green). If you believe your indoor lemon tree is getting WLD, consider moving it to a place with less light and monitoring the temperature of the leaves and roots.
Other issues with lemon leaves dropping can be due to low light, nutrient issues, or disease.
Over and under-watering can also cause leaf loss and slowly kill the tree. Monitor the top 2-3 inches of soil for dryness and water to keep the soil moist. If you’re overwatering, or the soil is too dense, it can hold water and cause root rot. The root rot fungus will cause the roots to decay and leaves will begin to yellow and drop. Over time, the tree will die if it’s not repotted and properly recovered.
For more information about watering lemons trees, you can refer to my recent post: How Much Water Lemon Trees Need (With Real Examples).
When Should You Put Your Lemon Tree Back Outside?
Putting your lemon tree back outside will help it flourish from the increase in sunlight as well as access to pollinators. While lemons can self-pollinate, it can help to have the extra pollination from pollinators such as bees and hummingbirds. So, when exactly should you move your lemon tree back outside?
You should put your potted lemon tree back outside as soon as the last spring frost has passed. But first, gradually harden the tree off to the change of temperature over 3 weeks. Start with 1-2 hours a day and increase to full-time.
Lemon trees can become stressed if you change the temperature on them suddenly, even if it’s warmer weather. If you’d had your lemon tree indoors over the winter, gradually reintroduce it to the outside weather. Start with 1-2 hours a day for the first week, 2-3 hours the second week, and 4-5 hours the third week. After this, your tree should be acclimated to the weather and ready for staying outside full-time again.
Since it’s springtime, it might be a good idea to fertilize your tree to help it grow for the next year. Be careful not to over-fertilize it, especially with a synthetic store-bought fertilizer, as the high amount of nitrogen can burn the tree. Instead, use a small amount of fertilizer or consider using 1-2 inches of compost as a safer option.
If you’d like more information on fertilizers for your indoor lemon tree, check out my recommendations for citrus tree fertilizer, or make your own citrus fertilizer from kitchen scraps.