The ideal growing conditions commonly associated with spring and early summer allow cool-season forage plants to attain their peak growth rates very quickly, and as a result, accumulate a large volume of high quality leaf material in a very short period of time. Unfortunately, the progression from high quality green leaves to low quality stems and dead leaves is also very rapid during this time of the year.

During the first 30 days of growth, the quality of the pasture will peak and if not harvested at least once during this time period, begin to decline. During the second 30 to 45 days of growth, the quantity of pasture herbage will peak and then also begin to decline. If the herbage is not grazed or in some other manner harvested during this time period, by mid to late summer the forage mass will consist mostly of low quality dead brown leaves and stems, and exhibit a reduction in yield as well.

This occurs because as most pasture plants increase in age, they generally decrease in digestibility and quality. Also, as the height of the forage mass increases, the leaves in the upper portion of the canopy intercept most of the sunlight, and the lower leaves in the forage mass become shaded and die, which results in a loss of yield. Finally, once the plants have been triggered to move from the vegetative to the reproductive stage, generally, no new leaves or tillers will be produced until after flowering has taken place or the seed heads are removed by grazing or mechanical harvest. However, once the plants complete their reproductive phases, they again begin to actively tiller. Although forage growth rates and subsequent yields tend to be lower in the fall as compared with spring due to shorter day lengths, early fall is generally a period of increasing forage production as well increasing forage quality.