Rubber plants (Ficus elastica) are popular houseplants known for their large glossy leaves and sculptural shapes. Though they typically grow as shrubs indoors in nature rubber plants can reach over 100 feet tall as massive trees.
One unique feature of mature rubber trees is the development of aerial roots. These roots grow down from the branches and eventually reach the soil, acting as additional support structures You may be wondering – why do aerial roots grow on rubber plants? And what should you do if they start to emerge on your own specimen?
Why Rubber Plants Grow Aerial Roots
There are a few key reasons why aerial roots develop on rubber trees as they mature:
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Structural support – On full-grown rubber trees, the extensive network of aerial roots helps support the weight of the heavy branches and foliage. The roots grow thick and wood-like over time.
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Access to moisture and nutrients – Aerial roots allow the plant to absorb additional moisture and minerals from the humid air and rainfall. This supplements nutrition obtained through the soil.
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Adaption to the tropical climate – In the hot, humid tropical regions where rubber plants originate, aerial roots are extremely beneficial for moisture absorption. They also help provide support in loose, wet soils.
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Climbing aid – Some of the aerial roots grow into thick woody vines that help attach the epiphytic young plants to the branches of host trees as they climb upwards in dense jungles.
Do Indoor Rubber Plants Grow Aerial Roots?
Most indoor rubber plants will not develop aerial roots. Since they are grown as compact houseplants, they rarely reach the size and maturity required to initiate aerial root structures.
Additionally, the lower humidity levels indoors do not provide the ideal conditions to stimulate extensive aerial root growth. They are more likely to emerge in a greenhouse or enclosed patio.
If your rubber plant does produce aerial roots, it is a sign that conditions are optimal – warm, humid, with plenty of air circulation. Enjoy this unique feature! Pruning is optional if the roots look unsightly, as they are not essential structures on indoor plants.
Tips to Encourage Aerial Root Growth
While aerial roots are not critical for indoor rubber plants, you can try replicating ideal outdoor growing conditions to potentially promote aerial root development:
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Provide very bright, indirect light to encourage vigorous growth. Some direct sun is beneficial.
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Maintain warm temperatures between 70-85°F if possible. Cooler temperatures will retard growth.
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Increase humidity around the plant through pebble trays, misting, or humidifiers. 40-60% humidity is ideal.
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Ensure the potting mix never fully dries out. Allow the top inch to dry then water thoroughly.
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Gently circulate air around the plant using fans. Stagnant air increases disease risk.
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Feed monthly during the growing season with a balanced liquid fertilizer.
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Repot annually in spring to provide fresh, nutrient-rich soil.
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Prune back leggy growth to encourage bushier, stronger plants.
What To Do With Aerial Roots
If aerial roots do start to emerge from your rubber plant, here are some options:
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Carefully twist and wind the roots back into the potting mix near the base of the plant. This may stimulate them to grow into the soil.
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Gently tie the roots to a moss pole, board, or other support using soft plant ties or fabric strips. Avoid damaging the tender new roots.
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Train the aerial roots to grow into a decorative cache pot or container surrounding the nursery pot.
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Prune off any excessively long or unsightly aerial roots using sterilized scissors. This will not harm the plant.
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Option to leave the roots intact if you enjoy the unique rainforest-like appearance they provide.
Caring for Rubber Plants With Aerial Roots
Aerial roots require similar care to the rest of the plant. Keep them hydrated by misting 1-2 times per week with room temperature filtered water. Dusting the leaves and aerial roots regularly with a damp cloth will also help keep them clean and provide extra moisture.
Avoid exposing the aerial roots to direct sunlight, as this can scorch and dry them out. Carefully wrap or tie the roots back into the foliage canopy if needed to provide shade.
High humidity is critical for sustaining aerial root structures long term. Use pebble trays, humidifiers and frequent misting to keep humidity levels around the plant consistently above 50%.
Overall, enjoy aerial roots as a sign of vigorous growth. With the right care and conditions, you can sustain these unique structures and emulate the majestic, towering rubber trees found in tropical jungles.
Common Questions About Rubber Plant Aerial Roots
How long do aerial roots grow?
In ideal warm, humid conditions aerial roots can grow several feet long quite quickly. Growth will be slower in lower light and humidity. On outdoor rubber trees they reach all the way to the ground.
Do I need to mist or water aerial roots separately?
Misting 1-2 times per week is usually sufficient for indoor aerial roots. Avoid overwatering as wet roots risk rotting.
Should I prune off brown or dry aerial roots?
Yes, cleanly trim off any shriveled or brown aerial root sections to prevent disease spread. Sterilize pruning shears between cuts.
Can I propagate a rubber plant from an aerial root?
It is difficult but possible. Take a 4-6 inch section of healthy aerial root and place in water or moist soil to attempt propagation.
Why are the aerial roots growing up instead of down?
Occasionally aerial roots grow upwards seeking light and air circulation. This is normal. Gently try training them back downwards if desired.
Enjoy the Unique Qualities of Aerial Roots
One of the most intriguing features of mature rubber trees is their curtain of descending aerial roots that lend an exotic, tropical vibe. Though indoor specimens may never reach massive proportions, you can still admire aerial roots as a sign of vigor.
With the right growing conditions and care, the aerial roots can be sustained long term. Or simply prune off any excess growth if the aerial roots look unsightly or get unruly. Either way, admire them as an emblem of your plant’s aspiration to emulate its towering ancestors in the rainforest!