Fig trees (Ficus carica) are native to the warm, dry climates of the Mediterranean and Western Asia, making them vulnerable to the harsh conditions of winter in colder hardiness zones. While mature trees can tolerate temperatures down to about 15°F, a hard freeze below 10°F can cause significant damage to the above-ground wood, and colder temperatures threaten the root system. Gardeners in temperate climates must employ specific methods to protect their fig trees, ensuring the plant survives the cold while remaining in a state of natural dormancy. The goal of winterizing is not to keep the tree warm, but to insulate it from extreme cold and temperature fluctuations.
Preparing the Fig Tree for Winter Dormancy
Preparation for winter begins long before the first frost to ensure the tree is properly hardened and ready for dormancy. Gardeners should stop applying nitrogen-rich fertilizers by late summer, typically around August or September, to halt the production of tender new growth. Preventing this soft new tissue allows the wood to mature and lignify, or harden, before winter arrives, as new growth is highly susceptible to cold damage.
Watering should also be gradually reduced as temperatures drop in the fall, which signals the tree to slow its metabolic processes. A slight exposure to the first few light frosts naturally cues the tree to drop its leaves and enter a deep dormant state. Once the leaves have fully dropped, confirming dormancy, any necessary light pruning should be completed, focusing on removing crossing or damaged branches to make the tree easier to wrap or move indoors.
Protecting In-Ground Fig Trees
Protecting fig trees planted directly in the ground requires creating a substantial barrier to insulate the roots and the delicate fruiting wood. The first step involves mounding a thick layer of insulation, such as soil, shredded leaves, or straw, around the base of the trunk. This mulch layer should be 12 to 20 inches deep to thoroughly protect the root crown, which is the most genetically resilient part of the plant.
For the above-ground structure, branches should be gently tied together using twine into a tight, upright bundle to reduce the overall surface area exposed to cold wind. A protective cage is then constructed around the bundled tree using wire mesh or stakes, creating a hollow cylinder. This cylinder is filled densely with insulating material, typically straw, shredded leaves, or burlap, which traps air and protects the bundled branches from low temperatures.
The entire cage is then covered with a breathable material like burlap or specialized tree wrap. In some cases, plastic sheeting or tar paper is added to protect the insulation from rain and snow. It is important to leave the very top slightly open or covered with an inverted bucket to allow moisture and condensation to escape, preventing the buildup of mold and rot within the insulation.
Overwintering Container Fig Trees
Fig trees grown in containers require a different strategy, as their roots lack the insulation provided by the surrounding earth. The container must be moved to an unheated, protected location once the tree has entered dormancy and dropped its leaves. Ideal storage environments include unheated garages, cold cellars, or sheds where the temperature remains consistently cool, ideally between 20°F and 50°F. This temperature range is necessary to keep the tree in a deep, sustained dormancy without risking root damage from freezing.
Before moving the pot indoors, it is a good practice to inspect the tree thoroughly for any pests that might overwinter and infest the storage area. During the deep dormancy period, the tree requires minimal to no light and only very infrequent watering. The soil should be allowed to become mostly dry, with watering occurring sparingly, perhaps once a month, just enough to prevent the roots from completely desiccating. Overwatering a dormant fig is a common error that can quickly lead to fatal root rot.
Transitioning the Fig Tree Back to Spring
The transition back to the growing season requires careful timing to avoid damaging the tree with late frosts or intense, unacclimated sun exposure. For in-ground trees, protective wraps and insulation should be gradually removed only after the threat of hard frost has passed and night temperatures consistently remain above freezing. Removing the thick insulation too quickly can shock the plant and expose new growth to cold damage.
Container trees that have been stored indoors must be slowly acclimated, or hardened off, to the brighter light and harsher outdoor conditions. Initially, the tree should be placed in a shaded, sheltered area for a few hours each day, with the duration of sun exposure gradually increasing over a period of one to two weeks. This slow process prevents sunscald, which is a burn-like damage to the tender, pale new leaves. A final inspection for any signs of mold, mildew, or insect activity that may have occurred during the humid conditions of winter storage should also be performed before the tree is fully returned to its outdoor position.