Planting new grass seed requires protecting the seed during its most vulnerable stage. Homeowners often wonder if adding a layer of covering material is truly necessary for successful establishment. Utilizing a proper covering maximizes the chances of the seeds sprouting and developing into a healthy, dense lawn.
The Purpose of Covering New Grass Seed
A freshly sown lawn needs a stable microenvironment to successfully transition from seed to seedling. Germination requires continuous moisture, and the primary benefit of any covering is to help maintain this dampness in the upper soil layer. An exposed seedbed loses water rapidly through evaporation, requiring constant, often impractical, watering. A light covering acts as a barrier to slow this moisture loss, keeping the seeds adequately hydrated until they sprout.
Newly seeded areas are highly susceptible to erosion from both wind and water. A protective layer helps anchor the seeds and the soil itself, preventing heavy rainfall or strong irrigation from washing the seeds into clumps or down slopes. Without this stabilization, seeds can be scattered unevenly, leading to a patchy lawn appearance. The covering material also shields the tiny seeds from direct impact, which can displace them or bury them too deeply to germinate.
Using a cover offers protection from wildlife. Exposed grass seeds are an easy target for birds, who can quickly consume a significant portion of the newly sown area. A light layer of mulch or other material hides the seed from view, discouraging predators from feeding on the soil surface. This covering also provides a slight thermal buffer, stabilizing the soil temperature and protecting emerging roots from drying out in direct sunlight.
Using Straw: Choosing the Right Type and Application
Straw is a traditional and highly effective material for covering grass seed, provided the correct type is used. Clean, weed-free straw is derived from the dry stalks of cereal grains like wheat, rye, or barley after the seed heads have been removed. It is crucial to distinguish straw from hay, which contains numerous seeds that will sprout into weeds in your new lawn. Selecting straw ensures you are not inadvertently introducing unwanted plants to the soil.
The application must be a very light, airy layer to avoid smothering the emerging grass seedlings. An ideal spread density is achieved when you can still see approximately 50% of the soil surface through the straw. This light application, often estimated at about one bale per 1,000 square feet, allows necessary sunlight and air to reach the seeds while still providing insulation.
Straw is lightweight and decomposes naturally over time. If applied correctly in a thin layer, there is usually no need for removal. The straw will break down into the soil as the grass establishes, adding a small amount of organic matter. It should be left in place until the new grass blades reach a height of 2 to 3 inches, which typically takes between two to four weeks, when the young lawn is strong enough to survive on its own.
Other Seed Cover Options
Specialized erosion control blankets, also known as seed blankets or mats, are an excellent alternative to straw, particularly for sloped areas prone to washout. These mats are often made from biodegradable fibers like straw or coconut coir and are held in place with netting and staples. They offer superior erosion control and moisture retention, and they do not require cleanup as they break down naturally.
Peat moss is a popular choice because it is clean and highly effective at holding moisture. However, it must be applied extremely thinly, as a dense layer can form a hard crust on the soil once it dries. This crust can impede delicate grass seedlings from breaking through to the surface, blocking germination. For smaller areas, a light dusting of screened compost or fine topsoil can also be used as a topdressing.
Compost and topsoil provide some nutrients to the seedlings but must be applied at a depth of no more than a quarter-inch. Hydro-mulch, often a mixture of wood or paper fiber and a binding agent, is a professional-grade option. This material is sprayed on as a slurry and forms a protective, weed-free layer that holds water exceptionally well for large or difficult-to-access areas.