Fewer leaves are available to intercept sunlight and plants require more energy for growth than they are able to produce through photosynthesis. In order to compensate, energy is mobilized from the roots. The roots become smaller and weaker as energy is used to grow new leaves. Plant growth is very slow at this time but the leaves are extremely palatable and nutritious. Phase 2 occurs when regrowth reaches one fourth to one third of the plant's mature size.
Enough energy is captured through photosynthesis to support growth and begin replenishing the roots.
This is the period of most rapid growth. During Phase 2, leaves contain sufficient protein and energy to meet the nutritional requirements of most livestock. Phase 3 involves continued plant growth and leaves become more and more shaded. The lower leaves die and decompose. Leaves use more energy for respiration than they can produce for photosynthesis.