Overseeding is an important part of lawn care that makes thin, patchy lawns thicker by mixing new grass seeds into the turf grass that is already there. A thick, lush lawn not only looks great, but it also keeps weeds down and can handle more foot traffic.
When overseeding, using the right soil amendment together with grass seeds can make all the difference between success and failure. The age-old question faced by homeowners is whether to use top soil or compost as the topdressing when overseeding lawns.
In this comprehensive guide, we will dig deep to unravel this dilemma once and for all. We will compare top soil and compost to determine which one is the better choice for overseeding your lawn and achieve a thick, verdant turf
Why Topdress with Soil Amendments for Overseeding?
Some people may wonder why they can’t just plant grass seeds on their lawn without adding anything to the soil, like topsoil or compost. Well, here are some strong reasons why it’s important to topdress with the right amendment when overseeing:
-
It helps keep grass seeds in place and prevents them from being washed or blown away.
-
It improves seed-to-soil contact leading to higher germination rates and better establishment.
-
It provides essential nutrients for grass seedlings to get off to a vigorous start
-
It retains moisture close to the surface for tender grass shoots.
-
It creates a barrier between seeds and birds looking for an easy meal.
Top Soil for Overseeding Lawns
Top soil is the uppermost layer of soil, usually the top 3 to 8 inches, that contains most organic matters and nutrients. When used for overseeding, here are the main pros and cons of using top soil as the topdressing:
Pros
-
Levels bumps and divots to create a flat surface for even growth.
-
Provides good stability and anchorage for grass roots.
-
Its mineral content balances pH for healthy growth.
-
Offers quick establishment due to nutrient availability.
Cons
-
Leads to uneven settling over time.
-
Too thick of a layer can smother existing grass.
-
Introduces risk of weeds, pests, and diseases.
-
Offers no long-term improvement in soil structure or fertility.
-
Dries out faster and needs frequent watering.
-
Can contain clods which hinder seed-to-soil contact.
Compost as Topdressing for Overseeding
Compost is organic matter that has been broken down by things like leaves, grass clippings, food scraps, and manure. Here are some pros and cons of using compost when you’re overseeding:
Pros
-
Releases nutrients slowly to feed grass seeds and roots.
-
Improves moisture retention and reduces watering needs.
-
Inoculates beneficial microbes that enhance soil health.
-
Helps loosen clay soils and increases aeration.
-
Environmentally-friendly and sustainable choice.
Cons
-
Provides no help with leveling an uneven lawn.
-
Potency varies based on compost feedstocks and process.
-
Immature compost can damage tender grass shoots.
-
Some kinds may contain viable weed seeds.
-
Requires reapplication to maintain effects year after year.
Which is Better – Top Soil or Compost for Overseeding?
Which should you use when you need to choose between top soil and compost for overseeding grass that is already there? Here are some important things to keep in mind:
-
For extremely bumpy and uneven lawns, top soil is the better choice to level the surface for uniform growth.
-
Mature, high-quality compost is preferable for improving thin or worn-out lawns by enhancing soil fertility and structure.
-
A balanced approach would be to use a thin layer of top soil just to smooth out major bumps and hollows. Then apply 1/4 to 1/2 inch of compost over the seeds to provide nutrients.
-
For predominantly clay soils, compost helps aerate the ground and makes it easier for tender grass roots to establish themselves.
-
Sandy soils that drain too quickly are better served by compost’s ability to retain moisture compared to fast-drying top soil.
-
If using top soil, inspect it thoroughly because poor quality types may contain viable weed seeds, undigested wood chips, and stones.
-
Well-decomposed, weed-free compost provides organic matter to soil while minimizing the risks associated with bringing in outside top soil.
5 Simple Steps for Overseeding with Compost Topdressing
For best results, follow these simple steps when using compost as the topdressing for overseeding your lawn:
Step 1: Mow the lawn shorter than usual to a height of 1 to 1.5 inches. This removes any material that can hinder seed-to-soil contact.
Step 2: Use a core aerator to punch holes across the lawn so compost and seeds can penetrate the soil surface.
Step 3: Spread a 1/4 to 1/2 inch layer of weed-free, finely screened compost using a broadcast spreader.
Step 4: Broadcast grass seeds according to the recommended rate for your lawn’s square footage.
Step 5: Use a stiff rake to lightly work compost and seeds into the aeration holes. Then water gently to moisten the topdressing.
Optional Step: Consider rolling the lawn with a water-filled lawn roller to press seeds firmly against compost and soil.
When to Avoid Using Straight Compost for Overseeding
Despite its benefits, there are a few scenarios where compost alone may not be the best choice for overseeding lawns:
-
If major depressions or humps exceed 1 inch, compost cannot level the surface adequately.
-
Pure compost topdressing on a thick lawn mat or heavy thatch can create floatation, preventing seed-soil contact.
-
Low-quality compost containing large pieces of twigs or uncomposted materials can cover seeds instead of nurturing them.
-
On sandy soils in arid regions, compost alone may not provide sufficient anchorage for seeds, increasing washout risk.
-
Where weed pressure is high, seeds in pure compost are more prone to bird attacks without soil covering them.
Maintaining Your Overseeded Lawn
Once you have completed overseeding, proper aftercare is vital for the grass seeds to flourish. Here are some tips:
-
Water lightly and frequently, keeping the top 1/2 inch moist until seeds germinate.
-
Allow soil to dry out partially between watering once seedlings are established.
-
Apply a starter fertilizer high in phosphorus to fuel root development.
-
Mow existing grass high (3-4 inches) to allow sunlight to reach establishing seeds.
-
After new grass reaches 3 inches, begin mowing regularly at the desired height.
-
Let new grass thicken up before resuming heavy use and foot traffic.
The Bottom Line
When overseeding thin, patchy lawns, using compost offers substantial benefits over top soil as the topdressing in most cases. Compost boosts soil health and fertility while avoiding the potential downsides of bringing in outside top soil.
However, for extremely bumpy lawns, a thin layer of top soil may still be required before applying compost and grass seeds. As always, the condition of your existing lawn and soil will dictate the best approach. Follow the tips above to give your grass seeds the best chance of success when overseeding with compost.
Step 2: Choose the Compost
Pick compost that was made in a hot process, where microbes and other living things gave off heat that reached more than 140°. The high temperature ensures that weed seeds and pathogens that were in the compost inputs have been neutralized. If you buy commercial compost or use municipal compost, you should be all set in that regard. If you want to use your own compost, use a soil thermometer to check it while it is still moving.
You should see and touch the compost yourself before placing an order. It is free of rocks, glass, and plastic. Does it have that earthy smell? When you squeeze the compost in your hand, does it clump together well but also break apart easily? If the compost doesn’t pass these tests, don’t buy it.
Compost spread out on the lawn
Step 5: Water In
Water in the compost with a sprinkler. A little water will help the compost get to the soil, and it will also reveal grass blades that are hidden, so they won’t get suffocated. When you water your lawn quickly, don’t use a lot of water at once. That will make the compost run off instead of staying where it needs to go.
Black Cow Manure & Top Soil @lowes
FAQ
What type of soil is best for overseeding?
Overseeding Soil has a very consistent texture that is composed of compost and peat loam this light, clean and weed free soil is a terrific top dresser for existing or new lawns in conjunction with grass seed.
Should you use topsoil when overseeding?
-
Nutrient Enrichment:Topsoil, especially if it’s enriched with compost, provides grass seeds with vital nutrients like nitrogen, phosphorus, potassium, and iron, promoting healthy growth.
-
Improved Soil Contact:Mixing seeds with topsoil ensures better contact between the seed and the soil, allowing for easier moisture absorption and nutrient uptake, which are crucial for germination.
-
Uniform Distribution:A pre-mixed seed and topsoil mixture can help ensure even distribution of seeds across the lawn, preventing patchy or uneven growth.
-
Simplified Application:Mixing seeds with topsoil streamlines the overseeding process, as it reduces the need for separate application steps.
Should I use compost or topsoil?
-
Benefits:Provides a stable base for planting, helps retain moisture, and can be used to level uneven ground.
-
Uses:Laying new turf, creating garden beds, filling in bald spots in lawns, and raising ground level.
-
Drawbacks:May not be as rich in nutrients as compost, and can be heavy and difficult to work with.
Should you topdress before or after overseeding?
Scarify and aerate your lawn first, then add a top dressing. Finally, fill in any bare spots with grass seed. Sep 26, 2023.