Most houseplants quite readily show that they aren’t getting the light they need. They start to stretch for the light (etiolate), they start growing sideways, toward the source of light, and their lower leaves turn yellow and start to die. However, some long-suffering houseplants are more stoic: they refuse to show they suffering, but instead live on their reserves. Then when their energy is exhausted, they simply kick the bucket (or pot, as the case may be)!
The rubber tree (Ficus elastica) is a typical stoic plant. When it doesn’t get enough light (and it loves bright light and even full sun!), the plant simply stops growing, period. It can remain there, apparently in perfect condition, for 6 months, 12 months, even 18 months, but without growing (and when a plant doesn’t put on new growth, that is not a good sign). Then when its reserves are completely depleted, a first leaf falls off, then another, and another, and another until there are no more left. This stoic plant, apparently tough as nails, will be dead within a month.
Among other plants that don’t display their suffering, think of the dieffenbachia and the various dracaenas. You have to be really observant to realize when these plants aren’t happy!
If the Plant Isn’t Getting Enough Light?
Move it closer to the window, to a more brightly lit window… or put it under a grow light. Read Are Your Plants Suffering from the Winter Blues? for other suggestions.
When the plant starts to get the light it needs, it will slowly recuperate and return to health. But try keeping it in a more brightly lit spot in the future!