Plants need light to grow. Once the leaves emerge from a seed, light becomes a requirement. While special grow lights are available for indoor growing, natural light from the sun is free and less is required by most plants. Vegetables require six to eight hours of sunlight a day, while many low- and medium-light house plants only require four hours of sun a day. Maximizing the sunlight streaming through your windows allows these plants to flourish indoors.
Choose a window that receives the necessary hours of sunlight. Use a south-facing window if available, and an east-facing window as a second choice. Use a north or west window only for low- and medium-light plant varieties.
Check around the window frame for drafts. Hold a lit candle near the edges of the window; if the flame moves or blows out there are drafts. Install new weather stripping if necessary. Drafts dry out and cool down plants, causing damage.
Decide how to display plants in the window. Place seedlings directly on the window sill or on a shelf set up in front of the window. Arrange house plants the same way or hang them from hooks in the ceiling.
Use a translucent shade on south-facing windows to diffuse the light for low- and medium-light-intensity plants. Direct sunlight may damage or kill the plants.
Supplement natural sunlight with artificial light during winter for high light-intensity plants. Place plants under artificial lights, spaced 6 inches above the top of the plant, for twice as long as they would normally need sunlight.