Rubber tree plants (Ficus elastica) are grown all over the world as houseplants. They thrive outdoors in their native tropical climate, where they grow as shade trees. The large, thick leaves are dark green, sometimes with a bronze or reddish tint when young. Rubber trees grow to 100 feet tall in the jungle, but in coastal southwestern California and the southern tip of Florida, where they grow outdoors in the U.S., they reach 30 to 45 feet.
Leaf Yellowing, Root Rot
The most common problems with rubber tree plants concern watering. Both under and over watering cause leaf yellowing. Poor drainage due to heavy soil causes leaf yellowing as well as root rot. Overwatering or watering too frequently is another cause of root rot.
Rubber trees adapt to dry indoor air conditions, but they prefer high humidity. Dry air causes leaf drop. Cold drafts and too little light are other possible causes of leaf drop. Adjust the placement of your rubber tree during the winter if these symptoms exist. Add supplemental plant lights if necessary, and move the plant away from drafty windows and doors.
The white sap of a rubber tree plant is a skin irritant. The sap causes gastric irritation if ingested. Keep children and pets away from rubber plants, and pick up dropped leaves.
Rate of Growth
Rubber trees grow very rapidly, and they can quickly outgrow their role as a houseplant. Not only do they need increased pot size to accommodate the expansion of roots and trunk, the trees grow taller, with denser, heavier limbs and foliage. Prune your rubber tree plant to help control its size.
Outdoors, rubber trees can become persistent, with large spreading roots. If a rubber tree is too close to a patio, sidewalk or other structure, the relentless roots can cause excessive damage.