The practice of covering newly sown grass seed is highly beneficial for establishing a healthy lawn. However, the answer to whether you should use hay over grass seed is simple: you should not. While mulching the seed is recommended, the material used should be straw, which is often mistakenly referred to as hay. Straw provides the necessary protection without the significant drawbacks associated with using actual hay for seeding projects.
The Essential Role of Seed Coverings
Covering new grass seed with a light layer of organic material creates a microclimate that significantly improves germination success. This protective layer regulates soil temperature, preventing extreme fluctuations that can stress delicate seedlings. A consistent soil temperature helps ensure a stable environment, which is conducive to rapid and even seed sprouting.
Another primary function of the covering is moisture retention, which is arguably the most important factor for successful germination. The mulch acts as a barrier, slowing the rate of water evaporation from the soil surface. This ensures the seeds have continuous access to the damp conditions required to break dormancy. Without a covering, the seeds and surrounding soil can dry out rapidly, particularly in direct sunlight or breezy conditions.
The covering also provides mechanical protection against environmental forces and pests. During heavy rainfall or on sloped areas, a light mulch prevents seeds from being washed away, minimizing soil erosion and keeping the seeds in place. This layer also serves as a mild deterrent, making the exposed seeds less accessible to birds and other small animals.
Hay Versus Straw Making the Right Choice
The distinction between hay and straw is paramount when seeding a lawn, as they are fundamentally different products. Hay is the entire dried plant, such as alfalfa or ryegrass, baled for use as livestock feed. Because it is harvested while the plants are mature and contain reproductive parts, hay bales are full of seed heads from the original forage crop.
Introducing hay means scattering thousands of foreign seeds that will inevitably germinate alongside the intended grass seed. These unwanted seeds, often vigorous and fast-growing, quickly compete with the new lawn for sunlight, water, and nutrients. This competition results in a patchy, uneven lawn infested with weeds that are difficult to eradicate later.
Straw consists of the hollow, dried stalks of cereal grains like wheat, oats, or barley, harvested after the grain seeds have been removed. As a waste product of grain farming, straw is typically seed-free or contains only a minimal amount of grain seeds, making it a safer choice for mulching. This material provides necessary physical benefits—lightweight structure, moisture retention, and erosion control—without introducing a widespread weed problem.
If straw is unavailable, alternative commercial products are safer options than hay. These include:
- Peat moss
- Paper mulch
- Specialty seed coverings
These engineered coverings are designed to be sterile and often contain tackifiers that help them stick to the soil and prevent wash-out. Choosing these clean materials guarantees the new lawn will not be contaminated with foreign grasses and weeds.
Applying and Maintaining the Protective Layer
Once the correct material, typically wheat or barley straw, is selected, proper application ensures successful growth. The goal is to create a very thin, breathable layer that provides protection without smothering young grass shoots. A common recommendation is to spread the straw so lightly that approximately fifty percent of the soil remains visible through the covering.
This layer is often described as “one straw deep” or roughly a quarter-inch in thickness, allowing ample sunlight to reach the germinating seeds. Applying too much straw will block light, impede air circulation, and reduce successful seed growth. One standard bale of straw is sufficient to cover around 1,000 square feet of a newly seeded area.
After spreading the straw, it should be lightly patted down with the back of a rake or a push broom to ensure good contact with the soil. This action helps anchor the straw, making it less likely to be scattered by wind or water. The area must then be thoroughly watered, as moisture helps settle the straw and start the decomposition process.
Throughout the germination period, the straw helps maintain consistent moisture in the top layer of the soil. Watering should be frequent and light to keep the soil surface damp without causing runoff that could displace the seeds or straw. The straw is left in place until the new grass reaches a height of about two to three inches, ready for its first mowing. When applied thinly, the straw will naturally break down and decompose, adding organic matter to the soil and eliminating the need for manual removal, which could otherwise risk damaging the fragile new seedlings.