The lemon has been known in southern and central Europe since the days of the ancient Roman emperors. The exact origin of the lemon tree is unclear, but its homeland is believed to be Central Asia. Even today, the lemon still thrives in subtropical and tropical climates because the lemon tree cannot tolerate frost.
Can a lemon tree tolerate frost?
Lemon trees (Citrus limon) are not frost hardy and should be overwintered in a winter garden, greenhouse or room at temperatures between 5-10 °C. The more robust Meyer lemon (Citrus limon “Meyer”) can withstand down to -5 °C, while the frost-hardy bitter lemon (Citrus trifoliata) can withstand down to -25 °C.
Lemon tree is not hardy
The classic lemon varieties (Citrus limon) are neither winter nor frost hardy and should therefore always be overwintered in the winter garden, in the greenhouse or in a suitable room. However, there are more or less sensitive varieties. The Meyer lemon is probably the most widespread lemon as a container plant. Citrus limon “Meyer” is much less sensitive to climatic conditions than any other lemon. Temperatures down to around minus 5 °C are no problem when it is in hibernation.
Description of the frost-hardy Meyer lemon
The growth of the Meyer lemon is bushier than that of other lemons. The flowers often appear profuse. The plant is not as susceptible to leaf loss in winter. However, when fully ripe, the orange, relatively round fruits with a very thin, soft peel taste tarter than you would expect from lemons. But even the relatively undemanding Meyer lemon should not be planted out in the garden, but should be kept as cool as possible over the winter.
Optimal temperatures for overwintering lemons
Lemon trees should ideally be overwintered in a location that is as bright and dry as possible with average temperatures between around five and ten °C. In this case, the plants are in hibernation and require significantly less light and water than in the growing season. Due to the lack of light in winter, lemons should be put into hibernation if possible, otherwise additional light-giving plant lamps (€79.00 at Amazon) should be installed. The vegetation phase begins at sustained temperatures above 15 °C.
Frost-hard bitter lemon
In contrast to the “normal” lemon varieties, the bitter lemon Citrus trifoliata (also Poncirus trifoliata) is frost hardy down to temperatures of up to minus 25 °C. Due to the typical three-part leaf, the bush, which is up to three meters high and heavily thorny, is also known as the “three-leaved orange”. The bitter lemon is the only type of citrus to shed its leaves in autumn. The relatively large, paper-like flowers have no scent. The fruits of the bitter lemon are inedible due to the high content of bitter substances. The plant is suitable as a pretty ornamental shrub in the garden and, because of its robustness, is also the best growing base for growing lemons and other citrus plants in containers.
Tips & Tricks
Citrangen (crosses of oranges and bitter lemons) were also bred as robust, virus-resistant grafting rootstocks. These varieties are also often frost hardy and are suitable as ornamental shrubs in the garden, unless you really want to harvest tasty lemons.