Kentucky bluegrass is a cool-season variety that requires adequate fertilizer and water. Lawns that are stressed or unhealthy have an increased risk of developing disease or insect problems. Use caution and apply the proper amount of fertilizer to Kentucky bluegrass to prevent damage from nitrogen or chemical burning.
Kentucky bluegrass grows best in a nutrient-rich and well-draining soil. Working 2 to 3 inches of organic compost into the soil with a tiller before planting increases the nutrient value. Organic compost is a form of fertilizer that naturally breaks down in the soil to supply nutrients to the grass as it grows.
Kentucky bluegrass requires a higher level of fertilizer during the first year to establish a strong root system. Apply 1 lb. of a high nitrogen grass fertilizer for each 1,000 square feet of lawn space. Repeat this application five times during the first growing season, beginning with an application after the first mowing. Water the lawn well after each fertilizer application or its high nitrogen content may burn the grass.
Fertilizer applications made on established lawns are lower than the amount needed during the first growing season. Apply 1 lb. of a high nitrogen grass fertilizer for each 1,000 square feet of lawn space. Repeat the application one or two more times during the growing season. Soak the lawn to stimulate absorption and prevent grass burn from the nitrogen.
Kentucky bluegrass requires up to 2 inches of water each week to stay green during the hot summer months. Apply deep soakings of 1/2 inch of water with each application. Place a shallow can on the lawn to measure the amount of water applied with a sprinkler system.
Kentucky bluegrass lawns that begin to yellow may have iron chlorosis. This is common in alkaline soils where the iron level is low. Repair an iron chlorosis problem by spraying the grass with a 2 oz. ferrous sulfate solution for every 1,000 square feet of lawn space. Check the fertilizer to verify it is low in phosphorous; too much phosphorous increases a iron chlorosis problem.