Rubber Tree Plants and its Characteristics
The popular garden variety Rubber Plant or ficus elastica is also called a rubber fig, rubber bush, Indian rubber, or erroneously called a rubber tree. It is not to be confused with the Para Rubber Tree which is the main commercial source of latex or rubber making, although the ficus elastica also yields a milky white latex substance. It is native to India, Nepal, Myanmar, Bhutan, Malaysia, Indonesia, the West Indies, and Florida, U.S.A.
The rubber plant grows to a height of around 98 to 131 feet, so technically, it can still be called a tree. It usually develops a stout trunk of around 6 to 7 feet in diameter. The whole plant develops deep buttressing roots to anchor it into the soil to support the heavy branches. The plant is recognizable by its shiny oval leaves that are smooth to the touch.
Unlike other plants that need to produce colorful or fragrant flowers to attract insects for pollination, this member of the genus ficus requires a specific species of fig wasp for pollination. The rubber plant is mostly grown around the world as an ornamental plant with almost no commercial value from its latex compounds. It can actually grow in both tropical or colder climates as both an outdoor or indoor plant.
This variety of rubber plant also contains a milky white latex sap that contains the same chemical compound that can also make rubber. However, its distant cousin, the Para Rubber Tree, is more commercially viable as a source of latex for rubber because it can pour out more latex. The latex of elastica is an irritant to the skin and eyes and is poisonous if taken internally.
Varieties of Rubber Tree Plants
Aside from the ficus elastica which is the focus of this article and Para Rubber Tree, there is a third variety, the Panama Rubber Tree.
Castilla Elastica or the Panama Rubber Tree is native to Central America (hence its English name), northern South America, and the tropical areas of Mexico. It is the rubber tree for the principal source of latex for rubber making during the pre-Columbian times. The Mesoamerican tribes found several uses for the rubber produced from the Panama Tree latex including the rubber balls used in the deadly Aztec Olmecs ballgame ollamaliztii. Olmeca in the Aztec language means “rubber people.”
As mentioned earlier, the Para Rubber Tree or hevea brasiliensis, is the most common and commercially well known of the three varieties of rubber trees because the milky latex extracted from the tree is the world’s primary source for natural rubber. Although the tree can grow to a height of more than 130 feet in the wild, cultivated trees in rubber tree plantations grow much shorter owing to the drawing of the latex that restricts the tree’s growth. Aside from the shorter plantation trees because of latex extraction, Para trees are cut down after 30 years because latex production declines as the tree ages beyond 30. This variety of rubber tree only grows in tropical or subtropical climates with plenty of rainfall. Cold weather or frost can be disastrous on the tree’s latex production. After old rubber trees are cut down, the wood is harvested for furniture making.
How to Care for Rubber Tree Plants
Rubber plants hate sitting in stagnant water so a well-draining soil container is important whether the rubber plant is container planted outdoors or indoors. Therefore, a good and proven draining and well-aerated potting soil are needed. The usual suggestion is to mix 1 part peat, 1 part pine bark and 1 part coarse sand, or perlite, which makes for a good mix for rubber tree soil.
Rubber plants like bright light and lots of it, but not direct sunlight. A sunny spot that is shielded is often perfect for rubber plants. You can tell if your rubber plant needs more light if it becomes leggy, its leaves lose their luster, and lower leaves fall off. For indoor rubber plants, take care not to house plants in rooms that receive direct sunlight the whole day. A good measure for the proper lighting in a room is to keep the plant in a room where one’s shadow can be easily seen on the wall behind the plant throughout the course of the day. Too many leaves falling off is a common occurrence with rubber plants that are placed in areas that are too dark or too drafty. When growing rubber plants indoor, avoid drafty areas near large windows, air vents, and opening doors. When outdoors, avoid cool and shady areas that receive too little full sunlight. If severe leaf dropping occurs, discontinue fertilization until the leaf dropping stops and move the plant into a warmer and better-lit area.
Watering and Fertilizing
Rubber plants and their watering needs will vary according to the season. When the plant is still in its growing stage usually in the summer, the plant and soil should be kept moist, but with no excess water. This includes wiping the leaves with a damp cloth or misting them with a small spray bottle.
During the dormant season, your plant will only need water once or twice a month. However, do watch out for drooping leaves that will indicate a need for more water. Leaves that turn yellow and brown or just drop off is a sign of over-watering. Use a mist spray bottle for any season if the air is too dry, especially with heated dry air from indoor heating during the winter if the rubber plant is indoors. If outdoors, water only once a month, or as necessary, again observing the behavior of the leaves. If the plants are indoor and you plan to use tap water, let the cold tap water stand until room temperature as this allows chlorine to evaporate and reduces the shock that cold water can cause to plant roots, turning it into lukewarm water ideal for watering.
Fertilize your rubber plant during the growing season only, as is typical with most indoor or outdoor plants of this type. For the young roots of rubber plants, whether indoor or outdoor, apply a high phosphorus fertilizer to stimulate root development. As the plant matures to producing much foliage, apply a high nitrogen fertilizer every four weeks during growth as this stimulates full and healthy foliage development.
A Mini-Guide to Pruning and Repotting
Naturally, you will need to remove all dead and dying leaves. Do take note that rubber plants do not require much pruning.
However, for shaping, take note of the following important tips: Don’t cut off the top until your plant reaches the desired height that you want. When you do start cutting off the top, your rubber plant will branch out. You can always prune the plant to your desired shape by cutting back unruly branches. Pruning in spring or summer is best, although this is not absolutely necessary. Also take note that if you do not re-pot your plants, they will not grow. However, do not put rubber plants in pots or containers that are too big. Transplanting to pots that are about an inch bigger in diameter than the previous pot is the best way of transplanting to give the roots more space to grow out. You can mulch only once a year.
When growing and when reaching its desired height, rubber plants are actually gorgeous to look at especially with its glossy leaves. Indoors or outdoors, they make for pretty ornaments. So if the time comes that your siblings or close friends ask for a rubber plant they can add in their garden, rubber plants are one of those plants that you can just hack a piece from and stick in soil and they will grow.
Allowing the sap to dry, dipping the cutting in rooting medium, and adding a heating pad under the pot with the cutting in it can increase your chances of success. It usually works the majority of the time, so if you can, give out a couple or three branches to increase the chance of propagating a new plant in a new garden. If you are propagating more yourself, you can also use the air layer method. The method of air layering is where you make a cut in a healthy rubber tree houseplant, put a toothpick in the hole, then pack damp moss around the cut. After this, wrap it with plastic wrap to keep the moisture level higher. Once roots begin to appear, cut the branch off and transplant. To promote new leaf growth where leaves have fallen, cut a notch in the node from where the leaf fell off.
Common Problems (Pests and Diseases) and How to Treat Them
Like any plant, despite the rubber plant being a very hardy plant, they can still be susceptible to many common pests such as mealybugs, scale insects, spider mites, root knot nematodes, and thrips. Pathogen (fungal and bacterial) problems may also occur in the form of leaf spots, crown gall, twig dieback and Southern Blight. However, most are easily preventable with a bit of care, though.
Southern Blight. This plant disease is caused by the fungus Sclerotium rolfsii. This common disease usually just referred to as ‘blight’ is an easily preventable moisture-related infection found in rubber trees during the summer months. Early symptoms include reddish or yellow spotting on the lower leaves, particularly with indoor or outdoor rubber plants that are regularly misted or overwatered. As the infection progresses, masses of cotton like fungi with hard brown lumps appear around the base of the stems and eventually spread up the stems and on the leaves. Because Southern blight is a devastating infection that is difficult to treat, prevention is the best option. Only sterilized potting medium should be used when re-potting rubber trees and water should be given sparingly during the growing season, taking care to keep the leaves dry.
Crown Gall. This is a bacterial infection affecting the roots and stems of rubber trees, caused by bacteria called Agrobacterium tumefaciens. The disease is characterized by swollen areas along the stems and it can cause large, disfiguring masses to appear that can be very deadly to the plant. The roots can also be affected and are then inhibited from absorbing nutrients and moisture. Unfortunately, there is no treatment for crown gall, and any infected plants must be destroyed to prevent the spread of the bacterium. For prevention against crown gall:
- Try selecting resistant cultivars when possible and purchase plants only from a reputable nursery.
- Do not buy plants that show signs of swelling or galling.
- When caring for infected plants, avoid pruning wounds that may come in contact with the soil. Existing galls can be removed with a sharp pruning knife. Destroy the infected plant tissue and treat the wound with pruning sealer. If the plant does not recover, remove and destroy it.
- Use tree wrap to protect the plants during winter against airborne bacteria and keep your garden tools clean. You can provide additional winter protection with natural burlap so bark does not crack.
Although crown gall is non-treatable once it spreads, you can try this method of treatment. Remove the infested plant and prune out the gall tissue. Soak the entire root system and damaged areas for 15 minutes in a solution of 2 level tablespoons of Actinovate per 2-1/2 gallons of water. Replant in healthy soil and apply 1/2 tablespoon per 2-1/2 gallons of water as a foliar spray at weekly intervals. After a couple of hours, if the plant doesn’t heal, destroy it completely so it doesn’t infect other rubber plants.
Xanthomonas Leaf Spot. This is another of the more common diseases found in rubber trees that are caused by bacteria called Xanthomonas campestris. The disease is characterized by tiny oozing spots that appear on the leaves, eventually causing them to turn yellow and eventually die out. The spots rapidly grow in size and are often bordered by bright yellow discolorations that spread between the leaf veins. Copper-based bactericides can keep the infection from spreading if applied early. Be extra careful when applying because they can harm healthy tissue if overused. This common disease can be prevented if excessive watering is avoided and fertilizer is used sparingly only during the season needing fertilization.
In reality, few diseases actually attack rubber plants. Overwatering plants so that the soil becomes waterlogged is the main culprit of all rubber tree diseases that favors pathogens to grow in the soil. Root rot, which is caused by various fungal pathogens, such as the Phytophthora species, causes roots to decay and is often signaled by yellowing leaves. Foliar nematodes, or Aphelenchoides, are microscopic roundworms that will infect rubber tree’s leaves as they feed and cause the areas between leaf veins to turn yellow and die. It should be noted that there is no control for this disease and you must discard infected plants.
Thrips. These are tiny winged insects popularly known to attack rubber trees exclusively. Although some cultivars of rubber tree are resistant to thrip infestations, most commonly available ficus that have grown indoors are susceptible to them, not having developed the resistance that outdoor plants usually have. Early symptoms include silvery-gray scarring under the leaves where feeding has occurred, often causing infested leaves to curl and drop off. They can be controlled and prevented with commercially available insecticide.
Mealybugs. These are white and waxy insects that sometimes colonize the undersides of rubber tree leaves. Early signs of a mealybug infestation include drooping or very dry leaves and the appearance of cotton-like masses along leaf attachment sites and on the undersides of the leaves. Manual removal of mealybugs is difficult and seldom effective, although spraying the affected area with an alcohol and water solution can lessen the severity of the infestation.
Other pests like aphids, spider mites, and scale insects are also primary pests of rubber plants. Aphids are like mealybugs that are soft-bodied insects that pierce plant tissue and feed on cell sap. Spider mites are tiny arachnids that also feed on cell sap. You may see telltale signs of their presence by the delicate webs they spin before you notice the mites. Sap-feeders such as scale insects leave stippled or speckled leaves as they remove chlorophyll. They often go unidentified because they live underneath protective scales that they use as armor against predators. If you manage these pests early, your plant will only suffer minimal damage. However, unchecked feeding from these sap feeders results in unattractive leaves that eventually drop off from the plants. Horticultural soaps or liquid insecticides that you apply as a soil drench may be effective in treating these pests when used according to the directions on the label.
Other Things to Keep in Mind When Growing Rubber Tree Plants
Even though rubber plants can grow in both tropical and cold climates, they are severely sensitive to temperature changes. Rubber plants like warm environments and respond best to temperatures between 12 or 13 and 26 or 27 degrees Celsius. If temperatures drop below this, they may respond with discolored or disfigured leaves. Young leaves may pucker and leave some brown blotches while maturing. Locations near air conditioners are not suitable for a rubber plant, indoors or outdoors. These plants are also sensitive to being moved and may drop their leaves if you move them from their familiar growing spot. Although new leaves will grow, the plant will become unsightly until they fill out with leaves again.
Save Water from the Kitchen and the Fish Tank
After boiling vegetables, don’t throw away that water from the pot. Of course, let it cool down before using it to water your plants. There are added vitamins and minerals in this water that can help nourish your plants. The same goes for used water from your fish tank because it is rich in phosphorous and nitrogen that can aid in plant growth.
Apply Mulch to the Soil
Mulch provides a protective layer that can prevent up to 70 percent of moisture from evaporating, especially on a hot day, you always want to keep growing rubber plant soil moist, but not overwatered, and never dried out. Whether you decide to do composting or not on your rubber plant soil, apply an adequate layer of mulch to avoid water runoff. Mulching also keeps weeds from taking over precious soil space and vying for water and nutrients, which your growing rubber plants badly need.
Rubber plants can reach a height of 10 feet inside your home if you allow it to. You can be size-prohibitive with the rubber plant through pruning unless you have vaulted ceilings. You can easily prune these plants to conform to your room height, but each pruning cut will exude a sticky white sap that is poisonous. It can cause contact dermatitis that irritates your skin and it can cause burning inside mouths and throats. Because it is poisonous if ingested, keep children and pets away from newly pruned plants until pruning wounds heal and the sap stops flowing. If your child or pet likes to chew on plants, a rubber plant is not the ideal plant for your home, whether outside or inside.
Whether you decide to grow a ground-bound garden or container garden, rubber plants grown in proper containers are a great addition to any home garden because of its beauty and gorgeous looks due to its shiny leaves. So long as the rubber plant is kept at a proper height, say at around 8 to 9 feet high, or lower if it’s an indoor plant, it will look good in any garden or home. Just don’t allow a rubber plant to grow to its full height unless you’re planning to set up a rubber plantation right on your property.