Should I put compost down before laying turf?

When preparing to lay new turf or sod in your yard, one of the key steps is preparing the soil properly. This ensures the grass has the nutrients it needs to establish a healthy root system and thrive. One question that often comes up is whether you should put down compost before laying new turf. The answer is yes, applying quality compost before laying sod can provide multiple benefits.

What is Compost?

Before examining the benefits of using compost when laying turf, it helps to understand exactly what compost is. Compost is organic material that has been broken down into soil-like material through the process of decomposition. Quality compost contains a mixture of:

– Decayed plant and food material such as leaves, grass clippings, straw, and vegetable scraps
– Manure and biosolids from animals
– Wood chips, sawdust, and shredded bark
– Soil

This mixture creates a dark, crumbly, earthy material that provides nutrients plants need. Compost introduces beneficial microorganisms to the soil that help plants extract nutrients. It also improves the physical structure of soil by breaking up heavy clay soils and helping sandy soils retain water and nutrients better.

Why Put Down Compost Before Laying New Turf?

There are several key reasons why it is recommended to spread a layer of compost over the soil before laying new sod or turf:

Increases Nutrients in Soil

One of the biggest benefits compost provides is increasing the nutrient content of the soil. As it breaks down, compost releases macro and micronutrients into the soil that grass needs to grow deep roots and stay healthy. This includes nitrogen, phosphorous, potassium, calcium, magnesium, sulfur, iron, zinc, manganese, copper and boron.

Improves Soil Structure

Compost also contains humic acids that are beneficial for improving soil structure. Humic acids help bind tiny soil particles into clumps, creating a better environment for roots to grow and penetrate the soil. The organic matter in compost also lightens heavy clay soils and helps sandy soils better retain water and nutrients.

Increases Water Holding Capacity

The increased soil organic matter provided by compost also improves the soil’s ability to absorb and hold moisture. This is very important for newly laid turf, ensuring the grass roots get sufficient water to establish themselves.

Promotes Healthy Root Growth

In addition to providing nutrients and improving soil structure, compost introduces beneficial microorganisms to the soil. These microbes form symbiotic relationships with grass roots, helping them take up nutrients from the soil. The microbes also produce growth-stimulating hormones that encourage stronger, deeper root growth.

Reduces Erosion

Laying new turf often involves grading and digging up the top layer of soil first. This can leave the soil loose and prone to erosion from wind and rain. Spreading a layer of compost over the soil provides protection from erosion while the new sod takes root. The compost acts as a blanket securing the soil.

Lowers pH of Alkaline Soils

Compost made from leaves, wood chips and other plant-based materials releases organic acids as it breaks down. These organic acids help lower pH levels in alkaline soils. Lowering pH helps make nutrients already present in the soil more accessible to grass roots.

Suppresses Weed Growth

Using compost when laying turf can help suppress weed growth. The increased microbial activity and improved soil structure make conditions favorable for turf grass growth but less ideal for weed seed germination and establishment. The compost acts as a barrier blocking light from reaching potential weed seeds in the soil.

Provides Pest Protection

The diverse community of microorganisms found in quality compost also helps protect turf grass against fungal diseases and harmful pests. Beneficial bacteria and fungi compete with and ward off turfgrass pathogens in the soil and on the roots.

How Much Compost Do I Need?

When laying new turf or sod, a general rule of thumb is to apply compost at a rate of 1 cubic yard per 1,000 square feet of area being covered. Here are some more precise guidelines:

– For sandy soils, apply 3/4 to 1 inch layer of compost over soil before laying turf
– For loamy soils, apply 1/2 to 3/4 inch layer
– For clay soils, apply 1/4 to 1/2 inch layer

Applying compost too thick can potentially obstruct grass roots from reaching down into the soil beneath. It is better to err on the side of less compost and you can always add more later by topdressing.

What Type of Compost is Best?

When selecting compost, you want mature compost made from quality ingredients. Here are some things to look for:

– Organic matter content over 50%
– A dark brown or black color
– No unpleasant odors
– A crumbly texture, not soggy
– Does not contain visible weeds or debris
– pH between 6.0-7.5

Compost with these characteristics has finished the decomposition process and provides the most nutrients and benefits. Avoid compost with a sour or ammonia smell, which indicates immaturity. Steer clear of compost containing visible weeds seeds, plastic, glass or other debris as well.

Should I Turn the Compost into the Soil?

There are differing opinions on whether you need to mix compost into the native soil before laying sod or just spread it evenly over the surface. Incorporating compost deeper into the soil profile can potentially provide benefits, however it also disturbs the soil structure.

A disadvantage of turning the compost into the soil is it requires extra work. Using a rototiller or spading the compost in by hand takes more effort but does mix the compost down 6-12 inches into the soil.

The easier method is simply spreading the compost in an even layer across the top of the soil and then laying turf directly over it. This allows the compost to break down slowly and naturally filter into the soil. It also creates an organic mat that encourages stronger root growth in the sod.

Step-by-Step Guide to Spreading Compost Before Laying Turf

Follow these steps for properly applying compost before laying new turfgrass sod:

1. Remove Old Grass and Weeds

First remove any existing grass, weeds or plant debris from the area getting new sod. You can use a sod cutter, scraper or shovel to strip off the old vegetation. Remove any sticks, rocks and debris that could create uneven areas under the new turf.

2. Rototill Soil

Use a rototiller or spade to loosen up and break up the first 4-6 inches of soil underneath where sod will be laid. This allows compost to mix in more easily. Rake the area flat and smooth.

3. Spread Compost Evenly

Spread compost evenly across the prepared soil using a shovel or compost spreader. Maintain the recommended depth based on your soil type. For optimal root development, do not exceed 1 inch depth.

4. Water Thoroughly

Use a sprinkler or irrigation system to thoroughly water the compost. This allows the compost to settle into the soil surface. The added moisture also kick starts the composting process.

5. Grade and Compact Soil

After watering, use a rake, lawn roller or landscape grading tool to gently flatten out any uneven spots. This creates a smooth, consistent base for laying the turf. Avoid excessive compaction that could overly restrict root growth.

6. Lay New Turf

With the compost spread and moistened, you can begin laying new turf or sod over top of it. Roll out each section carefully and ensure good contact between the sod and soil surface. Stagger the seams between each turf section.

7. Water New Turf

Gently water the newly laid turf to help the sod establish roots in the soil profile. Avoid overwatering before the turf takes root. The compost layer under the sod retains moisture well for the grass.

Turf Laying Tips When Using Compost

Here are some helpful tips to get the best results when using compost as part of laying new turfgrass sod:

– Purchase quality turfgrass sod free of weeds and pests
– Lay turf within 36 hours of harvesting to ensure sod stays fresh
– Roll out strips of sod tightly together but avoid excessive overlaps
– Use sod staples to secure sod strips on sloped areas
– Water sod thoroughly but avoid saturating mucky soil for 1-2 weeks
– Allow sod to establish roots for 3-4 weeks before heavy use
– Consider organic fertilizers to provide added nutrients
– Monitor new turf closely; apply more compost as needed

Does Using Compost Guarantee Lush, Weed-Free Turf?

Spreading compost before laying turf provides highly beneficial properties for establishing strong, healthy grass. However, using compost does not by itself guarantee perfect, weed-free turf. Proper ongoing lawn care and maintenance is still required after laying sod.

Compost aids the soil structure, fertility and microbial life that all support lush grass growth. But factors like weather, drainage, watering, mowing height, fertilization and pest control also impact results.

Quality compost reduces, but does not eliminate, the need for supplemental fertilizer on newly laid turf. Some weed seeds may still germinate through the compost layer. Careful maintenance helps the grass outcompete weeds.

So while compost provides ideal conditions for turf to flourish, it does not ensure perfect results on its own. Diligent lawn management and care is still essential after laying new sod.

Frequently Asked Questions

Is compost necessary or can I just lay sod directly on soil?

You can certainly lay turfgrass directly over soil. However, this misses the many benefits provided by using compost as an intermediary layer. Compost improves soil structure, fertility and health in ways that soil alone often lacks.

Should I fertilize the soil before spreading compost?

Pre-fertilizing the soil is not necessary when also applying compost. Good compost contains ample nutrients to support newly laid sod. Excess fertilizer combined with compost can cause nutrient burning of grass roots.

Can too much compost harm my new lawn?

Yes, applying compost too thickly can potentially harm turf. Excess compost can obstruct roots from penetrating down into the soil. It can also lead to overly moist conditions that encourage fungal disease. Stick within the recommended 1/4 to 1 inch depth based on your soil.

Will compost keep all weeds out of my new turf?

Unfortunately no, compost alone will not prevent all weeds from emerging in a newly sodded lawn. It can suppress many weeds, but not block every single weed seed. Careful maintenance and quick weed removal is still required after laying turf.

Should I apply fertilizer after laying turf over compost?

Allow the new sod to establish a strong root system over 3-4 weeks before fertilizing. Then apply a balanced organic fertilizer according to product instructions to provide nutrients to help the new turf thrive long-term.


Putting down compost before laying new turf or sod offers clear benefits for establishing a lush, healthy lawn. The compost provides essential organic matter, nutrients, and a biologically rich substance. This creates an ideal medium for grass roots to rapidly take hold and grow.

While using compost does not guarantee perfection, it sets your new turf up for success. Follow the proper steps for laying high-quality compost and sod for your best shot at a gorgeous new lawn. Pay close attention to good maintenance practices after laying the turf as well. Your efforts will be rewarded with a thriving turfgrass lawn everyone will envy.

Leave a Comment