Why Won't My Grass Seeds Germinate?

grass image by Brett Bouwer from Fotolia.com

An expanse of green lawn is the major element of most home landscape designs. Regular maintenance, beginning with the initial seed planting, is necessary to keep your lawn looking its best. Healthy lawn establishment relies on proper seed germination and sprouting. Unfortunately, new grass seed may fail to germinate for a variety of reasons.


Like many other types of plants, grass seeds require adequate soil warmth to germinate and begin to grow. The correct time for planting grass seed depends on the type of seed and the climate. The best times to seed a lawn are during the spring and fall seasons when the soil temperatures are above 10 degrees Celsius. Planting too early in the spring or too late in the fall can subject the seeds to freezing temperatures and ruin their chances of sprouting.


Grass seed needs some light to sprout and even more light to grow. Planting the seeds too deep can block out the available light, keeping the seeds from germinating. While some varieties of grass, such as creeping red fescue, can tolerate moderately shady conditions, planting new grass seed in heavily shaded areas can affect the rate of germination.


Grass seed requires frequent and thorough watering. Initially, the water helps to soften the hard, outer coat around the seed, known as the endosperm. Without this primary moisture, the grass seeds will fail to begin the process of germination. Letting the soil dry out after the seeds begin to soften is one of the main causes of poor establishment in new lawns. The small seedlings' immature systems are incapable of storing water and require even moisture availability at all times.


Some grass seed fails to germinate regardless of the planting care and maintenance. Extreme temperatures can damage grass seed before you plant it in the ground. Seed subject to high temperatures during transportation or storage may fail to germinate. Seeds previously exposed to high levels of humidity or dampness can start germinating in their containers, eliminating the chance of growth once they reach the ground. Another common cause of seed damage involves diseased seeds. Fungal diseases -- such as powdery mildew, red thread and rust -- may infect the seeds during processing and packaging, limiting their ability to germinate and grow.

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