I found this on the internet:
Most ficus trees are given preferential care in the greenhouse, nursery or flower shop. The homeowner unwittingly brings a ficus home into a 10 percent to 15 percent relative humidity environment, doesn't mist to compensate, fails to pour off the excess water in the saucer, waters with cold tap water or doesn�t give the plant enough water. The plant drops leaves in response, with crown thinning or dieback taking place. Many houseplants are at their low ebb at the end of the winter months. Most will begin showing new growth as daylight increases and the use of centralized, indoor heating decreases. All you can do is cut out the dead, woody tissue. Encourage and nurture anything that shows life with tender, loving care. Mist with distilled water and lightly fertilize as new growth commences. When summer sets in, move the ficus outdoors for several weeks to a protected location to give it a shot of energy before moving it back inside.