Answer: Rubber trees (Ficus elastica) do best with little light and very little water. They don't like wet feet. Let the soil dry out between waterings.
They do best when slightly pot-bound and should only be repotted every 2-3 years. You can use regular potting soil but a soil mix for cactus would be a good choice as well (because it will drain well).
You might try it in a location that's less bright also. Summer's approaching and maybe it's getting a little too much hot sun.
Finally, our water is extremely high in salts, which can build up in the soil quickly and destroy plant roots. Always flush plants with a slow and deep watering at least once a month to "leach" out these salts past the root zone. Let the water run out of the pot for several minutes. Good luck!
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