Updated: March 13, 2023
Houseplant low light

Light is probably the most essential factor for indoor plant growth. The plant’s growth, the length of active life, and energy derived from photosynthesis depend on the amount of light it receives.

  • Low light levels can result in few or no flowers and spindly, lanky growth as the plant stretches towards the sun.

  • To remedy the situation increase light levels by relocating plants closer to a light source or add additional artificial light sources.

  • Indoor plants can be classified according to their light requirements: low, medium or high.

  • Important aspects of indoor light are intensity, duration and quality. Light intensity depends on the distance of the light source from the plant.

  • The brightest light is found in a south facing window, bay window or sun room.

  • The duration is the length of time the plant receives light. Most flowering houseplants are indifferent to duration. However some houseplants such as poinsettia, kalanchoe and Christmas cactus only flower when day length is short, 11 hours or less.

  • Plants need some period of darkness to develop properly; so do not expose them to more than 16 hours of light.

  • Artificial lighting can improve the quality of light the plant receives. Red, far-red and blue wavelengths are most important for plant development. Incandescent plus fluorescent light sources or horticultural grow lights best mimic natural sunlight.