Most fertilizer is a blend of three main chemicals that many plants need–nitrogen, phosphorus and potassium. These nutrients are provided in air and water. However, due to weather and the rate of growth of the lawn, these nutrients can become depleted. Understanding your lawn can help you determine when it needs a dose of fertilizer to maintain healthy roots and steady growth.
Some types of grass grow more slowly than others. If the lawn is a fast-growing variety of grass, needing frequent mowing and watering, and if the clippings are removed, the lawn will need to be fertilized more frequently. Fertilizer should be added between late May and mid-June, again in August, September and midway through October.
Less Frequent Fertilizing
Lawns that are fast growing, frequently mowed and watered but allowed to retain the clippings do not require as many fertilizer feedings. The clippings naturally break down and augment the soil, returning some nutrients back to the roots over time. In this instance, fertilizer should be applied between late May and mid-June, in August and in mid-October.
Some lawns contain slower-growing grasses that require less frequent mowing or watering. If the clippings are removed, depriving the lawn of the nutrients provided by their breakdown, the lawn will require fertilization twice a year. Applications are recommended for August and mid-October.
Slow-growing lawns where clippings are allowed to remain need the least fertilization. Because the clippings break down slowly and the grass also grows slowly, the soil remains more balanced. These lawns can get by with just one application in September.
The numbers on bags of fertilizers found in gardening supply stores describe percentages of each chemical as 30-10-10 for example, in the order of nitrogen, phosphorus and potassium. Not all mixes contain the same proportions. Each different blend serves a different purpose, and it is important to understand their uses and when to apply them. To get the right blend, collect a sample of your soil in the fall or winter and have it tested by your local extension office. Collect a sample from the top 4-6 inches of soil from 10 spots in the area you want analyzed. Remove any living matter such as grass leaves and roots. Mix the 10samples together well and pack a 1-pint jar full of the mixture. The extension office can advise you of the exact blend of fertilizer needed for your lawn.