KC Gardens

September: Time to fertilize!

Fertilizing the lawn

Tip of the Week

It’s dinnertime for area bluegrass and tall fescue lawns, as they have depleted their food reserves. Just as we need certain vitamins and minerals to be healthy, turfgrass needs nutrients for healthy growth and development. Fall is the best time to apply these needed nutrients. After a summer of growth under our ever changing conditions our lawns are hungry and this meal will help rebuild the roots and crowns so that a dense lawn of our dreams will reappear.

September is the most important time for fertilizing. Nitrogen, the first number listed on a bag of fertilizer, helps thicken the stand and encourage development of a healthy root system. A strong root system is the foundation of a nice lawn. Cooler temperatures, fall rains and the addition of the nutrients help the lawn to recover from stressful summer conditions.

November is the next most important time to fertilize. The timing of this application should be about the time of 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 applications.

Choosing the right type of fertilizer is important. Nitrogen 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 than is available in the soil so it must be replenished on a regular basis.

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 is normally found naturally in the soils. Applications of fertilizers containing phosphorus and potassium are not recommended unless a soil test indicates the need. A starter type fertilizer, one higher in phosphorus can be applied when overseeding to help encourage quick establishment of the new seed.

Based on the need of the grass and local soil conditions, fertilizers containing higher concentrations of nitrogen should be used at this time. Bags of fertilizers will always have three numbers displayed. The numbers stand for the percentage of nitrogen, phosphorus and potassium contained in the bag. Examples of fertilizers to apply in the fall would be such numbers as 30-0-0, 27-3-3 or 25-5-5.

This emphasis on fall fertilization may conflict with some that promote spring applications. Cool season lawns experience a 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 little reserves for the stressful summer ahead. Therefore, it is best to wait until the flush is over, normally in early May, before making any spring applications.

Don’t let the dinner bell ring too long for your lawn, as a healthy serving of fertilizer is the best recipe for success after summer heat and drought. Remember — for fertilizer to become activated it must be watered into the soil either by natural rainfall or irrigation.

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