Of the four basic things every plant needs – light, water, nutrition, and climate – proper lighting is the most important. Adequate light is the key to photosynthesis. Without adequate lighting, plants grow weakly, are leggy, and may even die. Our eyes automatically adjust to varying light conditions, so what seems like bright lighting can be useless for plant growth. Natural sunlight is ideal for plant growth. For indoor gardening, it is up to the gardener to supply proper lighting, in adequate quantities and with the proper color spectrum, to replace that natural sunlight.