Why Will New Grass Seed Germinate But Not Grow?

Soil Moisture

• Grass seeds must be kept moist in order to germinate. However, gardeners should not forget about their seedlings once they emerge. If soil is left to dry out, seedlings die out. To prevent seedlings from drying out, water your soil so that the first 6 to 8 inches of topsoil is moist. Figure out how long to water your lawn by noting how long it takes you irrigation system to saturate the ground to a 6-to 8-inch depth. Water for an hour, for instance, then dig Dig an 8-inch to 12-inch hole in the soil wide enough that you can see on the hole wall where the wet soil ends and dry soil starts. Measure this distance. If you haven't watered enough, fill in the hole and pack it well, then water again. When you measure again, dig a new hole elsewhere in the yard. Note the times as you do this so you'll have an accurate measure of how long to leave your water on when watering. Alter your irrigation times according to the soil moisture.

Seedling Competition

• Distributing more than the recommended amount of grass seed for the particular type of turf you are sowing promotes grass seedling competition. Excessive grass seedlings compete with each other for the soil's moisture and nutrients, according to the University of Minnesota. The result is slow establishment time. Use the recommended distribution rate for your grass seed type. For example, distribute bermuda grass at 1 lb. per 1,000 square feet, whereas you should spread tall fescue at a rate of 8 to 10 lbs. per 1,000 square feet.

Soil Fertility

• You grass seeds may germinate, but if there are not enough nutrients in the soil for root development, they will have a difficult time growing. Gardeners must apply a starter fertilizer high in phosphorous at the time of seeding. For example, starter fertilizers with NPK amounts such as 5-10-5 spread at a rate of 20 lbs. per 1,000 square feet contribute enough nutrients for healthy root growth, according to the University of California. The healthier your roots the more energy they can contribute to producing grass blades.

Other Factors

• Grass seeds germinate and grow at different times depending on their types. Gemination rates differ from type to type. Gardeners must find out how long it takes for their grass seeds to germinate to know if their grass is not growing. For instance, it takes annual rye grass five to 10 days to ,while Kentucky bluegrass may take up to 30 days to germinate.