The four to eight week period following seeding is the most critical time for proper follow-up care when a dense, uniform, well rooted turf is being formed. There are more lawn establishment failures due to improper follow-up care during this time period than those due to improper seed selection, site preparation or seeding techniques.
Water is the most important factor in establishing a lawn. The initial watering should be a deep soaking – 4” to 5”. After that, follow-up irrigation should be done daily. The top ½” of soul should be kept consistently moist. Initially this may require morning, midday, and evening watering of about ¼” – ½” each time. A good way to determine how much water is being applied is to place a container (e.g. a coffee can) in the sprinkler’s path and time how long it takes to collect ½” of water. Light daily irrigation (¼” – ½”) should be continued for 3-4 weeks. During hot, dry conditions you may need to increase the frequency of watering to maintain moisture in the soil surface. As the turf develops, watering frequency can be cut back due to the shading effect on the soil. New turf still requires a minimum of 1” water a week for continued growth.
Fertilizer applications are also critical for the development of healthy established turf. A starter fertilizer that is high in phosphorus was applied at seeding time to promote faster germination. However, new seedlings need ½ lb. of nitrogen per 1,000 sq. ft. every 4 weeks. This can be applied in various forms (19-3-7; 20-2-7; etc.) and will result in a much healthier, thicker lawn than a lawn not fertilized. This rate should be continued for 4-8 weeks. The fertilization requirements provide the nutrients for growth and the ability to stave off disease, weeds, and insect infestation. Once the lawn has been established, a yearly maintenance program should be set up to maintain a healthy vital turf grass stand
Start mowing the new seed when the blades reach a height of 3½” to 4” removing only 30 percent of the leaf blade to a maintained height of 2½” to 3”. Cutting the grass shorter than 2 ½” will sacrifice root penetration down into the soil. The root system accommodates the height of the leaf blade so that the higher the height the deeper the root, resulting in a thicker, healthier lawn. Longer cutting height also gives the added advantages of conserving soil moisture due to increased shading and less area for weeds to penetrate.
The process of seeding exposes existing weed seeds in the soil to conditions favorable for their germination. Usually what you see in the first few weeks is a combination of annual grasses and broadleaf weeds. Although these weed type plants are unsightly, they can easily be eliminated in time. The general rule of thumb for eliminating broadleaf weeds is to wait until the entire turf area has been mowed 3-4 times before applying a liquid weed control or a granular fertilizer and weed control combination. Annual grass type weeds grow for 1 year, go to seed and die out. If you maintain a good fertilization program and watering schedule your turf should be thick enough the following year to eliminate the reappearance of annual grasses. Another option would be to apply crabgrass preventer to control annual grasses. This should be done only after your lawn has been in for a full year and no additional seeding is planned within 2-3 months prior to or following the application of the crabgrass preventer. The best time for crabgrass control is in mid-May. The longer you can tolerate the weeds the better for the new seed unless the weeds are so bad they are squeezing out the grass areas. Traffic should be restricted on a new lawn for at least a month. New seedlings are easily damaged by foot traffic.
Be patient with the progress of the new lawn. Seeding is by far the best way to establish a lawn for the long term. With proper care, as outlined above, you will have a healthy, enjoyable lawn for years to come.