Rubber tree (Ficus elastica), an evergreen native to tropical Asian climates, has multiple trunks, a wide-spreading canopy from which aerial roots often hang and surface buttress roots. It bears inconspicuous, white flowers. The tree is hardy in U.S. Department of Agriculture plant hardiness zones 10b through 11, but some of its cultivars have slightly different USDA zones.
In its native moist, hot, tropical forests, the rubber tree can grow 75 to 100 feet tall. In moist climates found in Florida, Hawaii and the Gulf of Mexico Coast, it grows 25 to 40 feet high, and its canopy spreads 25 to 30 wide. The tree retains its aerial and buttress roots in moist, warm climates.
When grown in frost-free, dry Mediterranean climates such as in California or arid climates such as in Arizona, a mature rubber tree is smaller than its counterpart in a moist, warm climate. Also, its canopy is narrower, it has fewer aerial roots and smaller buttress roots. For example, the tree may grow 5 to 25 feet tall in climates that are not the most favorable for its growth.
The rubber tree cannot tolerate temperatures below 32 F or above 115 F. It grows in partial shade or full sun, but a mature specimen tolerates only six to eight hours of full sun daily, and a rubber tree should not be exposed to the west in hot, dry climates. In those climates, it should be grown against an east- or north-facing wall.
Rubber trees were once grown as sources of natural rubber from their white, latex sap, but the sap can be troublesome when the trees are grown outdoors. Their stems and leaves drip the sap, which can stain sidewalks, patios and other surfaces.
The sap can cause skin irritation and/or serious, painful rashes. Wash your skin with soap and water after contact. If symptoms develop, call a physician or 1-800-222-1222, the national poison-control hotline run 24/7 by the National Capital Poison Center. An operator will connect you to the poison control center nearest you. If a dog or cat chews or eats the leaves or sap, the result may be diarrhea and/or vomiting. If either symptom happens, call the Pet Help Hotline at 855-764-7661.
Drooping branches of mature rubber trees require pruning to provide clearance for pedestrians and vehicles. When the trees are pruned, a tarp is required to catch staining sap dripping from cut wounds.
Rubber trees litter yards with falling leaves and fruits, requiring periodic cleanup. The 1/2-inch-diameter, green fruits do not attract birds or other animals.
Because of the way their branches grow from their trunks, and because their wood is weak, rubber trees are susceptible to wind damage.
Buttressing surface roots on rubber trees are obstacles for lawn mowers, and they can undermine sidewalks and building foundations.
Rubber trees grown indoors in pots do not have issues from litter, buttress roots or wind. Some rubber tree cultivars feature leaf variations:
'Doescheri' (Ficus elastica ‘Doescheri’) has marbled gray-green leaves with creamy-yellow midribs and green edges, and it has pink stems, making it prized for growing indoors in pots. Outdoors, it grows 20 to 30 feet tall and just as wide where it is hardy, USDA zones 10 through 11.
'Tineke' (Ficus elastica ‘Tineke’) has green and white variegated leaves with burgundy tones. It also is hardy in USDA zones 10 through 11 and grows 20 to 30 feet tall, but its spread is only 15 to 20 feet.
- Variegated rubber tree (Ficus elastica ‘Variegata’) has 5- to 12-inch-long, light-green leaves with yellow or white edges. It features multiple trunks and usually grows 25 to 40 feet tall with a 20- to 30-foot-wide canopy. It is hardy in USDA zones 10b through 11, where it is usually available at plant nurseries and garden supply centers.
- U.S. Department of Agriculture, Forest Service: Ficus Elastica, Rubber Tree
- Arizona State University, Chris A. Martin's Faculty Website: Ficus Elastica
- Horticopia: Fiscus Elastica 'Doescheri'
- California Polytechnic State University, Urban Forest Ecosystems Institute: Rubber Tree, Ficus Elastica
- U.S. Department of Agriculture, Forest Service: Fiscus Elastica 'Variegata,' 'Variegata' Rubber Tree
- OnlinePlantGuide.com: Ficus Elastica 'Doescheri'
- OnlinePlantGuide.com: Ficus Elastica 'Tineke'
- U.S. Geological Survey: Ficus Elastica, India Rubber Tree
- University of California-Davis: Safe and Poisonous Garden Plants
- National Capital Poison Center: 1-800-222-1222