Updated: Feb 7
Ficus elastica also known as the Rubber Tree, Rubber Plant or Rubber Fig is a tropical plant native to south and southeast Asia. The latex from the tree was once used for rubber production, but no longer serves that purpose. Instead, the Rubber Tree is now a very popular houseplant due to its ability to easily adapt to a variety of different growing environments including the low lighting of our homes.
In its natural tropical forest environment, Rubber Trees can grow epiphytically meaning they wrap their aerial roots around other trees for support until they establish strong enough ground roots to support themselves. Since these trees can quickly grow up to 130-feet tall with a trunk diameter of up to 7-inches, they need all the support they can get in order to prevent toppling over.
Although Rubber Trees can grow to be very large outdoors, they typically only grow 6-10 feet high when grown indoors due to constricted root growth in a pot and lower lighting than when grown outdoors. Rubber Trees can be grown outdoors in warmer climates, but can suffer if temperatures go above 90 degrees or below 55 degrees.
Rubber Trees can be trained to support posts such as tree stakes in order to support their tall growth and to prevent them from bending too far in one direction. The tree’s aerial roots will begin wrapping around the support posts and even back into the potted soil. The aerial roots can be pruned off if they become a tangled mess which can interfere with repotting the plant.
The Rubber Tree’s stiff, leathery leaves can grow up to 14-inches long by 6-inches wide, but become much smaller as the plant matures. This is an adaptation that occurs as a result of the young plants needing to be able to catch as many sun rays as possible since they often get shaded out by larger plants in their natural habitat. As the plant gets taller and is able to reach sunlight better, it no longer needs such large leaves.
The leaves of the Rubber Tree develop inside of a sheath that dries and falls from the plant as it unfurls with the leaf. This sheath and the new leaves have a red pigment to them which acts as a protective barrier until the new growth matures and becomes more hardy.
The typical Rubber Tree has dark green, almost black leaves, but there are variegated cultivars that add white, pink and light green pigments to the leaves. Variegated Rubber Trees require more sunlight because they lack chlorophyll. However, the variegated leaves are also more sensitive to sunlight and can develop brown spots on their leaves if they are placed too close to sunny windows. Set your variegated plants back a couple of feet from really sunny windows to avoid sun stress.
The Rubber Tree needs at least 6-hours of bright light a day to thrive. Without sufficient light, the plant will become leggy and weak as it stretches to find more light, followed by yellow leaves that drop from the plant. To avoid this, place your Rubber Tree close to a window where it can receive indirect sunlight. If you have a south or west facing window that gets heavy afternoon sunlight, consider setting your Rubber Tree a foot or two back from the window to avoid sunburns to its large leaves.
The more sunlight and warm your Rubber Tree gets, the faster its soil will dry out. Although the Rubber Tree is somewhat drought resistant, avoid letting the soil go completely dry. Prolonged periods of soil dryness will cause the roots to dry up and the leaves to brown and curl followed by leaf drop. Try keeping the soil consistently moist, but not soggy.
If your soil is not drying after a couple of weeks, it may be that the plant is not getting enough sunlight or that the soil is too dense. The less sunlight the Rubber Tree gets, the less moisture its roots will take up. The potting soil should be coarse with materials such as wood bark and pumice to provide air pockets for the roots to breathe.
Here are some potting soil suggestions for your Rubber Tree. (Your local plant nursery may even have their own mix):
Fertilize your Rubber Tree with a well balanced, slow release fertilizer such as Osmocote ‘Flower & Vegetable’ once every six months in the spring and fall. This fertilizer has an N-P-K (nitrogen-phosphorus-potassium) ratio of 14-14-14.
Water soluble or liquid fertilizers can also be used, but ensure you are measuring according to the directions to avoid nitrogen burns to the leaf edges and fast, but weak growth due to an over application of nitrogen.
Pruning & Propagating
Pruning your Rubber Tree to reduce its size or to encourage branched out, bushy growth can be easily done by pruning back each of the stems. Ensure you are wearing gloves when pruning your Rubber Tree as its sticky, white sap can cause irritation to the skin. Any sap that drips on furniture or flooring can be cleaned up with rubbing alcohol. Cuttings taken from the plant can be propagated in water to make new plants. Simply stick the cut end with a node at the bottom of the cutting into room temperature water or potting soil. Rooting hormone can be used to speed up the rooting process.
Step 1: Using bypass pruners, make a clean cut through the stem above a node or set of leaves.
Step 2: Prune back the cut off part of the stem to the next node. The node is where the roots will form. Any length of stem left past the node can rot in the propagation water or soil.
Step 3: Stick the cut end with the node in rooting hormone powder. The hormone in this powder can speed up the rooting process.
Step 4: Stick the cut in with rooting hormone into room temperature water or a coarse potting soil. If rooting your cutting in soil, ensure the soil is packed tightly around the cutting.
Step 5: Roots should begin forming within a few weeks. In order to tell if your cutting has rooted in soil, pot the cutting into a clear pot so you are able to see when the roots have formed. Ensure the cutting is placed close to the side of the pot so you can see them right when they form.
The most common insects that afflict the Rubber Tree are sucking insects such as mealy bugs, scale and spider mites that suck the sap out of the leaves. Common symptoms are tiny, white freckles on the top of the leaves, a sticky substance on the top of the leaves, webbing, black cylindrical larvae on the bottom of the leaves, a cottony white substance (mealy bugs) or brown insects living on the underside of the leaves (scale).
To treat these insects, apply a fungicidal soap to the entirety of the plant, including the underside of the leaves. Apply again in 7 days if there are continued signs of these insects. Wait 7 days between applications to avoid toxicity to the plant.
If you have any more questions about how to care for a Rubber Tree, we will be happy to assist you in a virtual telehealth appointment with one of our Plant Specialists. Please click on one of the options below to book an appointment.