It depends on the crop and its stage of growth. Many leafy greens are grown under long light periods indoors, while fruiting plants usually need more light overall. Check the requirements for your specific plant.
Use a Timer
A timer gives a consistent day length, which plants respond to. Keeping the same schedule each day is more important than hitting an exact number.
Watch the Plants
- Pale, stretched growth can mean too little light.
- Leaf scorch or bleaching can mean the light is too strong or too close.
Related guide: Lighting.
