Most citrus trees thrive in the warm, humid temperatures of tropical and subtropical climates. Very few of them are able to tolerate frost, and lemon trees (Citrus limon) certainly are none of these. In fact, lemons are extremely sensitive to cold temperatures, in accordance with Purdue University; much more so even than oranges. Because of this, and since the trees are attractive in their own right, many home gardeners decide to cultivate lemon trees indoors.
Climate and Temperatures
Outdoor lemon trees should only be cultivated in U.S. Department of Agriculture plant hardiness zones 9b through 11. In some instances, they may be grown in USDA zone 9a if the location is guarded from cold atmosphere, such as on wave. Generally speaking, they can withstand short periods of temperatures as low as between 25 and 30 degrees Fahrenheit. Low-lying areas aren’t a fantastic choice, especially in USDA zone 9a, since cold air tends to collect in ground depressions.
Frosts and Freezes
Frosts are brief periods of cold, clear weather with temperatures that may periodically drop down to about 20 degrees. In many cases, lemon trees can be protected from frost damage, as stated by the University of Arizona Cooperative Extension. Freezes, on the other hand, are much more lethal to lemons. These long-lasting periods of cold weather usually involve damaging winds and temperatures colder than 20 degrees that linger for several days.
Frost Protection
If the weather forecast calls for a frost, then water. The saturated soil will save its heat rather than radiate it into the atmosphere. Then, wrap your tree at a blanket. Finally, wrap the blanket with a string of Christmas lights, taking care to not get them wet. If your tree is not small enough for all these steps, spray the whole tree with water. Do this consistently throughout the length of the frost. The water will freeze above the leaves and twigs, which will actually help the tree’s wood tissue remain in an internal temperature of approximately 32 degrees, according to the University of Arizona Cooperative Extension.
Indoor Trees
Several lemon trees, including the popular Meyer lemon, develop very well in containers. If you reside in a USDA zone that is not conducive to outside lemon tree development, think about cultivating your tree in a pot. Move it indoors before the first autumn frost, or maintain it indoors year-round. Put the lemon tree in a sunny location where it will get between eight and 12 hours of sunlight per day. Keep the soil barely moist, and fertilize it with a slow-release, slightly acidic fertilizer.