It's fortunate for Ficus benjamina, also known as weeping fig, that it grows well in pots, because it can only thrive in the ground in frost-free areas. Because the trees can grow somewhat large without pruning, they do enjoy the freedom of the outdoors, even while kept in their pots. However, one severe frost can lead to severe damage or even death. Prevention of frost damage is key, but recovery is possible. The tree is hardy outside in U.S. Department of Agriculture plant hardiness zones 9 to 11.
As a tropical plant, everything about the weeping fig is tailored to warm weather. Weeping fig not only hates cold weather, it cannot survive in it. It may tolerate temperatures that dip near 40 degrees Fahrenheit, but once temperatures drop below this, the potential for tree damage increases. The weeping fig is hardy to 30 F, according to Arizona State University, but prolonged periods at this temperature can damage the branches and foliage. One hard frost is often enough to damage or kill the tree. If you keep the tree outside in winter, make sure sprinkler systems cannot reach it. The combination of water and cold may damage the tree.
Preventing Frost Damage
The best way to prevent frost damage is by moving the plant indoors when fall arrives. This is obviously only possible if you keep the tree in a pot. Don't wait until winter to bring the plant inside, because the temperature difference between outside and inside can stress the tree or shock it. Weeping figs should only be planted outside permanently if you live in a location that never receives frost. If your area does receive frost and you planted the tree in the ground, adding a 3- to 4-inch layer of mulch may prevent severe winter damage.
Signs of Frost Damage
After frost damage a weeping fig's leaves may turn from green to a yellowish-brown. Partial or full leaf drop may follow. Portions of the tree may still retain leaves, but some sections may drop them. Brittle-looking and dry branches are often another sign, indicating dying wood. The branches may also turn a darker shade of brown, sometimes even turning almost black. These symptoms -- especially the yellowing and loss of leaves -- may occur if you have watered the plant too much or too little and from root rot. If the symptoms coincide with a recent frost, it's safe to assume that's the culprit.
North Dakota State University horticulturist Ron Smith suggests cutting back affected branches until you see green growth at the location of the cut. The green indicates healthy, living wood. Scratch along the bark with a small knife or your fingernail to reveal the wood color. Pruning shears work on most branches, but thicker branches may call for the use of a handsaw. Use 45-degree cuts in relation to the branch help keep water from sitting on the cut.
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