Lemon trees are surprisingly tolerant to cold temperatures. But if you live in an area that has prolonged freezing temperatures in winter, you must take some extra precautions to protect your lemon trees.
Check the foliage. If the foliage is not a deep green color, add fertilizer. Healthy trees are more resistant to winter temperatures.
Keep your lemon tree watered. If you keep the soil around the roots moist, the soil can freeze without affecting the roots. When dry soil freezes, it leaches water from the roots and damages them.
Use an anti-transpirant once each month before winter. Anti-transpirants like Cloud Cover, Anti-Stress and Wilt-Pruf give the tree's foliage four degrees of protection against the winds and cold temperatures.
Drape a frost blanket over the lemon tree and anchor it with pins during cold snaps.
Hang Christmas lights on your lemon tree during winter. You can also use landscape lights at the base of the tree. The lights will give off heat to help protect from freezing temperatures. Leave the lights on all night when temperatures are lowest.