how many hours of light do indoor plants need
- If growing seedlings indoors, 16 to 18 hours of light at day is recommended, at 65 to 75 degrees F. This duration, or even 12 to 14 hours with brighter light, should be used if the sole light source for low to medium light plants. If using indoor lighting merely to supplement natural light from windows, you only may need a few hours additional at the end of the day.