Light is needed by a plant for using nutrients and manufacturing food. It has a great influence on chlorophyll production, growth rate, leaf size, and flower and seed production. One of the common problems encountered by the indoor gardener is poor light availability, particularly in apartments with limited window space or during winter when light intensity is low.
Artificial lights are useful when natural window light is insufficient.
The use of lamps encourages compact, luxuriant growth and regular blooming. As a supplementary light source, even a small portable reading lamp will improve plant health. It can be turned on for one or two hours at dawn and dusk to increase day length, especially in winter. Plants growing in a dim corner will visibly improve if they receive four to six hours of artificial illumination from an overhead light. Only when a plant's entire fight requirements are being met by artificial sources must special lighting provisions be made.