Plants need strong light in order to grow well indoors. The level of light that you find comfortable in your home is not nearly what a plant needs to thrive. Try this test in the spots where indoor plants are growing:
Move the pot and replace it with a sheet of white typing paper. Hold your outstretched fingers twelve inches above the paper. What sort of shadow do you see on the paper?
DIM SHADOW Only a few plants can tolerate low light. Try aspidistra, spathyphilum, snake plant or philodendron here.
MEDIUM SHADOW African violet, corn plant, pothos vine and spider plant do fine in moderate light. When the light is too dim, they can’t fight disease. Their leaves get brown spots and fall off.
DISTINCT, SHARP SHADOW This is the site for plants you have brought in for the winter. Hibiscus, geranium, coleus or ficus need strong light to keep their leaves during the winter. Cactus, donkey’s tail, bromeliads and Norfolk pine are tropical plants which must have bright light to thrive.
ADDING LIGHT If the spot you have tested has too little light, you can add light with compact fluorescent bulbs.
Buy a shiny aluminum “clamp light” at a hardware store. Screw in an LED floodlight or a compact fluorescent bulb equivalent to a 100 watt incandescent bulb. The light fixture must be as close to the plant leaves as possible! Bulbs more that four feet away give almost no usable light to a plant.
Modern LED bulbs will give the plants more of the light spectrum they would find outdoors.