However, applying too much fertilizer, or applying it at the wrong time of year leads to turf with excessive thatch, low drought tolerance, and a greater susceptibility to insects and diseases, increasing the potential for water pollution. Proper fertilizer application improves lawns and protects the environment. Recent research results have changed fertilizer recommendations. Timing of fertilization has been shown to be more important than the amount of fertilizer applied and less fertilizer than previously thought necessary is better. Fertilizers should be applied to turfgrasses only in the spring and fall.
Timing is important because it is related to how grass grows.
F will promote a vigorous, healthy root system and a hardier crown. Add the day's high and low temperatures and divide by two to determine the average daily temperature. This will keep the grass green longer into the fall, without excessive top growth. Then, an early June application is all that is needed to supply the turfs needs through the summer. Grass leaves grow most when daytime temperatures are between 60-75 o F. Fertilization during this period causes a dramatic increase in leaf growth.