How cold is too cold for a Meyer lemon tree?

If you live in a subtropical climate, you might be considering planting a Meyer lemon tree in your garden. If you don’t live in the subtropics, you might still be considering growing a Meyer lemon in a pot as a house plant, and moving the lemon tree between indoors and outdoors with the seasons. In either instance, you are probably wondering, “Just how cold is too cold for a Meyer lemon tree?”

The Meyer Lemon tree, discovered in the early 1900s and thought to be the cross of a mandarin and lemon, is actually more cold hardy than other types of true lemons, and can therefore be a desirable variety of lemon for growers on the edges of recommended citrus growing zones.

So how cold is too cold for a Meyer lemon tree? If the tree is mature, a short bout of frost is not likely to kill the tree, but damage and death is possible if temperatures below 29 degrees Fahrenheit are sustained. Younger trees should not be introduced to prolonged temperatures below 40 degrees. Meyer Lemon trees thrive best in temperatures between 50 and 80 degrees Fahrenheit.

Read on to find out more about growing a Meyer lemon tree where there is the danger of lower temperatures, and how to protect your tree from cold damage.

Temperature Ranges and Growing Zones of the Meyer Lemon Tree

Meyer lemon trees are happiest in climates where temperatures don’t dip below 50 or above 80 degrees Fahrenheit for prolonged periods of times. That said, Meyer Lemons can sustain temperatures down to 29 degrees Fahrenheit and will survive temperatures in the high 90s. Prolonged exposure to the high and low ends of these temperature ranges will affect your lemon tree’s production, however, and it may not bear much if any healthy fruit.

The best guidelines as to whether or not you can keep your lemon tree outdoors year-round are as follows:

  • A Meyer Lemon tree can thrive outdoors in growing zones 8 through 11.
  • Meyer Lemon trees can be grown indoors in a temperature-controlled environment in any growing zone where the tree will receive 6+ hours of sunlight per day.

The Danger of Frost and the Damage it Can Cause to a Meyer Lemon

While temporary temperatures below the frost point won’t kill a mature Meyer lemon tree, temperatures below 29 degrees Fahrenheit sustained for more than 30 minutes will certainly damage or kill your Meyer lemon tree.

If you have an outdoor lemon tree and live on the edges of the growing zones where frost is an unlikely but still possible danger, there are steps you can take to protect your lemon tree should the situation arise.

If you have an indoor lemon tree and are keeping it in a temperature-controlled environment, you won’t have to worry about frost, but there are other things you can do to make sure your lemon tree thrives through the winter months.

How to Protect Your Outdoor Lemon Tree from Frost

Even if you live in growing zones 8-11, where lemon trees are recommended to grow and thrive outdoors, the weather can still be unpredictable. A rogue cold spell is not out of the realm of possibility, and could damage or even kill your lemon tree. If you’re expecting a frost, you will want to consider taking precautions to protect your lemon tree.

Here’s what you can do to protect your lemon tree if you’re expecting frost:

  1. Pick all ripe fruit from your lemon tree. The fruit will spoil if temperatures dip below freezing, so pick what you can to enjoy. Picking the fruit also relieves limbs from extra weight that might strain or snap branches that are additionally stressed by frigid temperatures.
  2. Cover your lemon tree at night. Most likely your tree is most at danger of sustaining frost damage when temperatures dip during the nighttime. Once the sun starts to set, use cardboard wrapped securely around the trunk and secure with rope or string. Layer old blankets over the canopy of the lemon tree. This will provide a much-needed layer of insulation for the tree. Be sure to remove the coverings during the day, however, as your lemon tree will need access to the sunlight. Also, be sensitive to the maturity of your tree and the weight of the coverings you use. If your tree is only a few years old, consider using lighter blankets, tarps, or canvas.
  3. Give your lemon tree a good watering during the warmest part of the day. Trees that are water stressed freeze more easily. You will want to be sure that your lemon tree is well-hydrated. Water during the warmest part of the day when the sun is high, however, as you will want to make sure your lemon tree as ample time to absorb and intake the water before the possibility of a freeze.
  4. Consider decorating your tree with incandescent string lights, and turning the lights on throughout the night. Incandescent holiday lights produce heat while they burn, which can help your lemon tree battle the lower temperatures. Don’t bother if your lights are LEDs, however, as they do not produce heat.

How to Make Sure Your Indoor Lemon Tree Continues to Thrive During the Winter

If you are keeping your lemon tree indoors in a temperature-controlled environment, you will not have to worry about frost or freeze. That said, the colder temperatures and shorter days that winter brings can still cause an indoor lemon tree to struggle. Here are some tips to make sure your indoor lemon tree thrives through the winter months.

Keep your indoor lemon tree happy through the winter with these tips:

  1. Situate your lemon tree near your biggest and brightest window. Even in the winter, your lemon tree will need 6+ hours of sunlight a day. If your home windows do not facilitate that, or if your lemon tree starts to look a little sad as the days shorten, consider purchasing and rigging a grow light.
  2. Make sure that the window your lemon tree is situated near is properly shut and sealed, and is not leaky. Windows are already less insulated than walls and are consequentially quite cooler than other parts of the house. If your window is not airtight, gusts of cold air might cause minor confusion or stress to your lemon tree. While this is not a huge cause for concern, it will only help your lemon tree to make sure that your windows are shut tightly. Plug any gaps with insulation or silicon caulk. If your window is older and single pained, consider winterizing your window with plastic shrink film. Not only will your lemon tree thank you, but also your heating bill.
  3. Increase air circulation. During the winter, we close our houses up and recycle air in order to keep the heat inside and the cold outside. However, plants, native to the outdoors, love fresh air and need good air circulation for a variety of reasons. Good air circulation helps plants by replenishing CO2, regulating humidity, and preventing pests and disease. Having an updated HVAC system in your house with proper filters and fresh air intake can help wonders for your houseplants. If that’s not in the budget this year, situating a fan near your indoor lemon tree to provide a slight breeze can provide similar benefits.