Is a Lime Tree Resistant to Frost?

Susceptibility to Frost

• Several factors play a part in a citrus tree's chance of surviving a frost: the general health and vigor of the plant, characteristics of the species or cultivar, the rootstock supporting the plant and the duration and intensity of the cold spell. Any lime fruits should be harvested, and measures taken for frost protection, before the air temperature dips below 32 degrees Fahrenheit. Otherwise, ice crystals may form in the plant's cells, rendering water unavailable to plant tissues. If fruit is left on the branches, juice cells can rupture as ice crystals form inside.

Before a Frost

• For trees less than four years old, banking the trunk to about 15 inches with clean soil for insulation is the most effective means of cold protection. Bank trees in the fall before frost threatens, and leave the bank in place until danger of frost has passed, which in most locations will be in spring. When a frost is predicted, check the lime tree for insects. Hose off with plain water any scale insects or aphids found on the trunk or foliage. Water the tree well. These steps should improve plant health, so that the lime tree has a better chance of survival. Harvest the limes. They should be picked when immature and green for best flavor anyway; they turn yellow like lemons if allowed to ripen. You can freeze the juice in ice trays for future use. Bring container limes inside, set in a sunny window and reduce watering.

During a Freeze

• Various methods are used to protect lime trees from frost damage. Running a sprinkler through the night may help. Water gives off heat, and moist soil retains heat better. Extra lighting can also combat frost damage. Stringing Christmas lights in the tree may keep the cold at bay. Other methods used include installing landscape lighting or setting up a portable shop light at the base of the trunk. Another method involves blanketing the tree's trunk with either a commercial or DIY wrap. Tree wraps are sold in 40-foot rolls. Or you can drape a specially-designed tree blanket over the whole tree and lash it to the trunk or fasten to stakes in the ground. You can also tie organic materials, such as palm fronds or cornstalks around the tree. Pieces of cardboard also can work. Wrapping with tarps or plastic sheets is not recommended because the tree needs to breathe.

Damage and Recovery

• When a lime tree has sustained damage from frost, it can wither and turn black or dark brown. On the other hand, it may appear water-soaked. Resist the urge to prune out the effected parts right away. Waiting several months lets you assess the full damage and allows the tree to begin recovering when warm weather comes. As new growth emerges, prune out damaged twigs and smaller branches. Postpone heavy pruning, however, until the next year.