When used to cover grass seed, peat moss retains water more effectively than straw. This moisture forms a friendly environment for new grass seedlings and boosts seed germination rates. However, peat moss is acidic and antimicrobial, meaning it can be detrimental to your soil in the long term. Straw does not have any of the acidic qualities of peat moss and is a renewable resource. Harvesting peat moss is also environmentally destructive. So, while peat moss will help your grass seed sprout better in the short term, it can cause long-term damage to your lawn and the environment.
Do You Need to Cover Your Grass Seed?
Whether you are overseeding your existing lawn or spreading grass seed on bare earth, it’s essential to cover your grass seed. Uncovered grass seed is prone to drying out, being carried away by wind or water, and being eaten by birds. Simply covering your seeds with a thin layer of organic material is enough to boost the germination rate of the seed you spread. You’ll get far more grass sprouts by covering grass seed.
- New grass seed should be covered to prevent it from drying out or being scavenged by birds.
- Covered grass seed sprouts at a much higher rate than uncovered seed.
- Grass seed requires a covering material that will keep the seeds moist and break down into lawn fertilizer.
When searching for the optimal way to cover your grass seed, keep in mind that your seed cover needs to perform two essential functions. First, it should form a safe, moist environment. This will ensure that water is always available to the grass seed. Second, it should break down into a helpful lawn fertilizer so your seedlings get a jump start on life.
Which is Better when Seeding? Straw vs. Peat Moss
Straw and peat moss are two of the most common materials used for covering grass seed. Both are commonly available, fairly inexpensive, and constantly debated. So, which one is worth your money? What seed covering will lead to a better yard? Let’s dig into the pros and cons of both straw and peat moss, then deliver a final verdict.
Peat Moss: Pros
When you seed, you want an abundance of new grass sprouts. In this regard, peat moss beats straw. Simply put, you’ll get more new grass plants per square foot with peat moss than with straw. This is because peat moss soaks up water like a sponge. It can retain up to 10 times its weight in water, forming a perpetually moist environment that encourages seeds to sprout and prevents them from drying out during the early stages of life.
- Peat moss drives higher grass seed germination rates than straw.
- Because peat moss retains more water, it forms a better habitat for seeds and seedlings.
- When broken up and spread properly, peat moss does not form mats or smother grass seed.
- Peat moss does not contain weed seeds.
In addition to encouraging high germination rates, crumbly peat moss spread in a 1/8–1/4-inch (3–6 mm) layer over your lawn will not form clumps or mats that smother seedlings. The grass will easily be able to poke through the peat moss to receive air and sunlight. Plus, peat moss generally contains little to no weed seeds. You won’t introduce new pest plants into your lawn when you use peat.
Peat Moss: Cons
Peat moss is not good for your soil. Although much is made of the acidity in peat moss, it isn’t acidic enough to drastically shift your lawn’s pH balance. The bigger issue is that peat moss is antimicrobial. This means helpful soil microbes won’t grow in peat moss, which lowers your soil quality and reduces the nutrients available to your lawn. Not only that, but peat moss contains little to no nutrients. Even when it breaks down, it won’t add any positive nutrients to your yard.
- Peat moss is slightly acidic.
- Because it is antimicrobial, peat moss inhibits soil microbe growth and reduces soil quality.
- When it decomposes, peat moss does not add helpful nutrients to the soil.
- Harvesting peat moss is an unsustainable environmental hazard.
Not only will peat moss have a negative effect on the soil in your lawn, but the peat moss industry is also environmentally destructive. Peat moss grows at a rate of 1 millimeter per year and is harvested at rates far beyond what can be replaced. Wetlands are drained and destroyed to allow for the harvesting of ancient peat bogs. Peat moss is a non-renewable resource, which has led to upcoming bans on its use in some countries. This makes peat moss a poor choice for sustainable lawn care.
One of the big positives of straw is that if it is allowed to decompose, it will bring nutrients to your soil. Like spreading grass clippings on your lawn, straw breaks down into helpful organic matter and encourages soil microbe growth. It has none of the acidity of peat moss and far more nutrients. Even if your straw is taking a long time to break down after your grass seed has sprouted, you can rake up the remaining straw and add it to compost, or use it as garden mulch.
- Straw adds nutrients to the soil as it decomposes.
- Straw does not increase soil acidity or inhibit microbe growth.
- If your straw is decomposing slowly, rake it off your lawn to use as compost or mulch.
- Typically, straw is less expensive than peat moss.
- Straw is a sustainable resource.
Covering your grass seed with straw will also put less strain on your wallet than using peat moss. Straw is cheaper than peat moss, so it’s easier to seed your lawn on a budget. Even better, straw is a sustainable resource because it is a byproduct of fast-growing crops. You can protect your lawn seed in a sustainable manner and save money by opting for straw.
One of the biggest drawbacks of straw is that it often contains weed seeds. When you cover your grass seed with straw, it’s very common for weeds, as well as crop plants such as wheat, to sprout among your new grass. This can be extremely frustrating. Instead of new grass, you’ll instead find yourself cultivating invasive plants.
- Straw often contains weed seeds that sprout among your grass.
- Often, straw forms a mat that smothers grass seed.
- Straw does not retain water as well as peat moss, which can cause seeds to dry out.
- You will have lower seed germination rates with straw vs. peat.
Not only will straw bring weeds to your yard, but it also won’t provide an optimal environment for new grass seeds. Straw can easily mat together and smother seedlings, preventing growth. Plus, it only retains water moderately well. It may dry out on a hot day, killing off seeds that attempt to germinate. If you choose straw as your seed cover, expect to see fewer new grass sprouts than if you spread a layer of peat moss. There are also other straw alternatives for grass that can be used.
Verdict: Straw or Peat Moss for Grass Seed Cover?
If your primary goal is to get as many grass seeds to sprout as possible, peat is the clear choice for lawn topdressing. Whether laying new seed or overseeding, It will retain more water, won’t bring in weeds, and you’ll see a lot more seedlings than if you choose straw.
- Peat moss is the superior choice for encouraging a higher germination rate and preventing weeds.
- Straw is a better choice for practicing sustainable, eco-friendly lawn care.
- Neither peat nor straw is a flawless choice when covering grass seed.
If you’re concerned with taking care of your lawn in an earth-friendly manner, straw is the better choice. It is a sustainable resource that promotes much healthier soil in the long-term than using peat. However, it’s important to note that both peat and straw have their flaws when used to cover newly seeded lawns. That begs the question, is there a better option?
What is the Best Thing to Put on Top of Grass Seed?
Compost is the best option for covering new grass seed. Not only is compost a sustainable resource that fertilizes your soil naturally, but it also retains water to promote high germination rates, protects seeds from birds, and won’t bring weed seeds to your yard. If possible, use compost as your topdressing when seeding.
- Compost is an ideal cover for new seeds.
- The high nutrient and water-retention values in compost promote high germination rates.
- True compost rises to high temperatures as it decomposes, killing weed seeds, so it’s a safe fertilizer.
- Mix compost with topsoil for a low-cost top dressing to protect your seeds.
You can often find high-quality compost at low prices. This is an extra factor that makes it one of the best alternatives to peat moss. To make the price point even more competitive, consider making a 50/50 mix of compost and inexpensive topsoil to cover your grass seeds. You’ll create an incredible protective layer for your seeds on a budget.
Should You Use Peat Moss or Straw When Seeding Your Lawn?
Peat moss is better than straw at ensuring your grass seed germinates. This is because peat moss retains water to encourage seeds to sprout. Additionally, peat does not contain weed seeds, so it will not add pests to your yard. Straw not only often contains weed seeds, it also doesn’t encourage grass germination as well as peat. When it comes to starting seeds off right, peat is the better choice.