Nitrogen is an essential component in chlorophyll, which is the pigment that provides green leaves and stems with their color. Nitrogen promotes vegetative growth in plants.
Lawn grass, leafy green vegetables and plants grown primarily for their ornamental foliage require high levels of nitrogen for best performance. Insufficient nitrogen can cause the leaves and stems of some plants to turn yellow and wilt. Fruiting and flowering plants, however, have less need for nitrogen and may fail to produce viable fruits and attractive flowers if they receive too much of this nutrient.
Decaying organic matter such as compost, leaves and lawn grass clippings provide the main source of nitrogen for many home gardeners. Home gardeners and commercial farmers also often use synthetic fertilizers containing nitrogen.