Lemon trees originate from India and the Mediterranean Basin, enjoying warmer temperatures and little cold or freezing. Like most citrus trees, lemon trees are highly susceptible to damage and death due to freezing winter temperatures. If you live in a climate that experiences prolonged winter temperatures below 30 degrees Fahrenheit, you'll need to take special care of your lemon tree throughout the winter. You must take care not only to prepare your lemon tree for the winter, but also to protect the tree when frosts or freezes threaten.
Stop fertilizing your lemon tree by mid-summer to allow it to harden off for the winter. Don't resume fertilizing until spring.
Mound up clean soil around the trunk of your lemon tree if the tree is less than four years old. Mound up the soil around the tree to about 15 inches high before the first hard frost and remove the soil carefully in the spring, when all chance of freezing temperatures has passed.
Drape a blanket made of breathable fabric, such as cotton, over your lemon tree's branches to cover the tree when freezing temperatures or frosts threaten, if your tree is older than four years. Stretch the corners and edges of the blanket down and stake them to the ground with landscaping stakes. Be sure to cover all the branches completely and remove the blanket during the day when the sun is warm.
Remove all debris or mulch from the soil around your mature lemon tree prior to the first expected frost or freeze. Place a hose sprinkler beside the tree to irrigate the soil around the lemon tree for about three days prior to the first expected freeze or frost.
Hang Christmas lights in the lemon tree's branches to provide a heat source around the tree. You can also use electric lanterns or incandescent heat lamps, but use caution when placing any lights or heat sources near any blankets.