The best rubber plant soil is one that drains well, with a slightly acidic pH between 5.5 and 7.0.
The Ficus elastica, for example, can do well in a range of potting mixes. But it will thrive in a soil mix of one part potting soil or peat moss, one part perlite or sand, and one part pine bark.
The Effects of Soil On Plant Growth and Health
Soil supports the structure of plants by offering stability to the root system and providing moisture and nutrients.
For best results, the soil provided for a rubber tree plant should mimic the plant’s natural environment, that of the geographical point of origin of the species.
For example, the Ficus elastica originates from southeast Asia, as do most rubber tree plants.
Its preferred soil type, as described above, can be found in abundance in that region.
Rubber tree plants generally prefer humid rain forests that provide constant light, are rich in moisture, and where soil that drains readily is plentiful.
Signs You Are Using the Wrong Soil For Your Ficus Rubber Plant
The most common problem for a rubber tree plant is soil mixes that retain too much or too little moisture. Therefore, getting the right balance between water retention and draining is essential.
Overall, rubber tree plants want to be wet but not soaking. Signs of too much moisture:
- Yellow or brown leaves
- Drooping or dropping leaves
- Yellow or brown spots
Signs of too little moisture:
- Leaves feel crisp rather than waxy
- Leaves curling inward
These are all signs of stress. These signs indicate that an immediate change is needed to prevent the progress of these stress conditions toward the death of the plant.
The leaves of a rubber tree plant should be waxy, firm but not brittle, and bright, dark, or muted green.
The trunk and branches should be brown, exhibit fibrous bark, and be firm but somewhat flexible.
The Ideal pH Level For Rubber Tree Plant Soil
All varieties of rubber tree plants will do well in only slightly acidic soil.
They will tolerate extremes of pH between 5 and 8.3. But they do best in soils with a moderate pH between 5.5 and 7.0.
The size of the plant will dictate the weight of the potting mix that is best.
For example, a larger plant will do better in a soil mix that contains sand to provide aeration rather than perlite.
Conversely, a sand-heavy mix may be too restrictive for a smaller or younger plant, where perlite is likely best.
The ideal soil for a rubber tree plant will hold on to moisture but will not allow the water to pool around the roots and the base of the trunk.
Therefore, there should never be standing water. In a southeast Asian rain forest, these plants count on constant rain and light combined with well-draining soil.
For this reason, it may be necessary to set up an automated misting or drip system to provide constant water.
Finally, it is best to use a planter that can drain well.
A pot or planter that does not drain well can cause water to pool below the surface and go unseen, even if the surface of the soil appears to have the right moisture level.
Soil For Re-Potting Rubber Tree Plants
When re-potting, it is best to provide consistent, stable conditions. This is true for any plant, including rubber trees.
In all cases, the type of mix the plant has grown accustomed to is best.
For example, when transplanting a plant that has outgrown its perlite-heavy soil, consider using a mix of perlite and sand to transition the plant into a more sand-rich mix as it matures.