If a bright location is unavailable, supplement existing light with fluorescent light. While standard fluorescent lights are better than incandescent bulbs, they often lack the full spectrum of light needed for healthy growth. These bulb are specially designed to mimic the full spectrum of sunlight. To be effective, fluorescent light should be lit for at least one to sixteen hours per day. Herbs that are grown indoors also need cool temperatures and good air circulation.
Herbs also thrive on humid air.
Since furnaces can make indoor air hot and dry, you can provide extra humidity by misting the plants. However, too much humidity can result in mold and fungus growing on the soil surface or on the leaves. If you find your herbs developing fungal problems reduce the humidity and use a small household fan to stir the air. Starting Herbs Inside 1. Use new or recycled two-inch nursery pots.