Therefore, protect plants from too much direct sunlight during summer months. Incandescent lights produce a great deal of heat and do not use electricty very efficiently. If artificial light is the only source of light for growing plants, the quality of light or wavelength, must be considered. Plants require mostly blue and red light for photosynthesis, but for flowering, infrared light is also needed. Incandescent lights produce mostly red and some infrared light, but very little blue light.
Fluorescent lights vary according to the amount of phosphorus used by the manufacturer.
Foliage plants grow well under cool-white fluorescent lights, while blooming plants require extra infrared light. This can be supplied by incandescent lights or special horticultural fluorescent lights. Temperature Most plants tolerate normal temperature fluctuations. In general, foliage plants grow best between 70 degrees and 80 degrees F. during the day and between 60 degrees to 68 degrees F. at night. Cool nighttime temperatures are actually more desirable for plant growth than high temperatures.