September is officially here and this is the best time to fertilize cool season lawns such as tall fescue and bluegrass. Fall temperatures and moisture levels are ideal for replenishing the nutrients that the stress of summer depleted from the turf.
Fertilizers containing higher concentrations of nitrogen should be used at this time of the year due to our soil conditions. Nitrogen helps thicken the stand of turf and encourages development of a healthy root system. A strong root system is the foundation of a healthy lawn. After the heat and drought stress of summer, fall rains, cooler temperatures and an application of fertilizer is just what your lawn needs to recover. The fertilizer helps to thicken up thin areas in the lawn.
Bags of fertilizers display three numbers. The numbers stand for the percentage of nitrogen, phosphorus and potassium, in that order, that are contained in the bag. For example, fertilizers that would be appropriate to apply in September are 27-3-3 or 25-5-5. These fertilizers contain primarily nitrogen.
Choosing the right type of fertilizer is important. Nitrogen in fertilizer is the most important nutrient, as it is needed in the greatest quantities by the turf. It is essential for healthy growth, color and density. Vigorously growing lawns use more nitrogen than what is available in the soil, so it must be replenished on a regular basis through fertilization.
Phosphorus, the second number listed on the bag, is needed for growth of roots and shoots. Adequate quantities are often present in the soils of established grass.
Potassium, the third number listed, is essential for the overall health, stress resistance and cold hardiness of lawns. Like phosphorus, it normally is found naturally in the soils. Applications of fertilizers containing large quantities of phosphorus and potassium are not recommended for the Kansas City area unless a soil test indicates the need.
You might be scratching your head, wondering why I recommend fertilizing in the fall rather than the spring when all the commercials promote fertilizing. Cool season lawns experience a natural flush of shoot growth in the spring. Applying fertilizer before this flush is over can cause the grass to grow too fast. The rapid growth exhausts the plant’s food stock and leaves it with few reserves for the stressful summer ahead. Therefore, it is best to wait until the flush is over, usually in early May, before making any spring applications.
To provide your lawn with adequate food reserves for spring, fertilize in November, the next most important time to fertilize. The timing of this application should be around the final mowing of the season, normally mid-month. This enables the lawn to green up earlier in the spring, without encouraging the excessive shoot growth that often accompanies early spring application.
For more fall lawn care tips, Click here.
-- Chelsey Wasem