(Hint: Don’t Use Sand!)

Soggy, slippery, slushy soil is probably not what you had in mind when you envisioned your outdoor living space.

Poorly-drained soil leads to root rot, pest problems, uneven ground, and dead spots.

Fortunately, soggy soils have a tried-and-true remedy that includes a basic 4-step process to improve your lawn’s drainage:

  1. Core aerate each spring
  2. Topdress with compost
  3. Create an optimized mowing schedule
  4. Create an optimized irrigation schedule

So, wipe the mud off your boots and take a seat. Let’s solve this.

Why Lawns Have Poor Drainage

Healthy, loamy soils have a spongy, free-draining structure that holds shape in all but the most torrential downpours.

Sandy soils drain too freely and leach nutrients into the groundwater.

Clay soils are responsible for poor drainage. Clay soils are made from the smallest soil particles, and over time, these particulates pack together and cause compaction. Compacted soil has very low porosity, or air pockets, which makes it difficult for water to pass through into the subsoil.

So, the obvious answer is to add sand to clay, right?


Sand + clay = concrete

This is a formula for disaster.

Instead of mixing two poor soil structures, the real solution is to improve your existing soil structure and create a spongy, loamy topsoil.

Core Aeration

Core aeration removes cores of soil from the lawn and introduces oxygen into the root zone. This also allows organic matter to penetrate into the topsoil.

Core Aeration is one of the key ways of improving your lawn’s drainage.


Topdressing is the process of adding a thin layer of compost over the lawn and raking it into the holes left behind by core aeration.

This will replace clay particles with loose, free-draining organic matter. Over time, compost will accumulate in the root zone and create a more porous soil profile.

This is the most important task for improving your lawn’s drainage.

Optimized Mowing Schedule

Mowing is more than making your lawn look pretty. Proper mowing encourages deep, fibrous root growth, which will promote drainage.

Optimized Irrigation Schedule

Although it’s tempting to water frequently to promote lush, green growth, it’s not going to end well. Frequent, shallow irrigation encourages lots of surface-level root growth.

Deep root growth breaks up compacted soil. Promote deep roots by watering deep & infrequent, which forces roots to dig deep for their agua.

What You’ll Need

Improving clay soil is a long-term endeavor, but the most important tasks are aeration and topdressing. These steps are completed at the same time.

For core aeration, you will need:

  • A core aerator (not a spike aerator)
  • A sturdy rake

There are mechanical and manual options for core aerators. Clay soils are usually too compacted for manual aerators, so save your back the headache and opt for the machine.

For topdressing, you will need:

  • Lots of compost (formula below)
  • That sturdy ol’ rake
  • A shovel
  • A wheelbarrow
  • 3 gallons of sweet tea (seriously, though- stay hydrated)

Your goal is to spread ¼”-½” of compost over the top of your lawn. The formula for this is as follows:

  1. Calculate the square footage of your lawn: Length x Width
  2. Multiply the square footage by .02 for a ¼” layer, or .04 for a ½” layer
  3. The resulting number is the amount of compost you need in cubic feet
  4. Divide by 27 to find cubic yards

Example: a 20’ x 35’ lawn is 700sq’.

700sq’ x .04 (½” layer) = 28cu’.

28cu’/27 = 1.03 cubic yards.

For mowing & irrigation, you will need:

  • A mower with a sharp primary blade & mulching blade
  • A form of supplementary irrigation (sprinklers, irrigation system, etc.)

Although these may seem obvious and trivial, proper mowing and irrigation is critical to root health, and root health is critical to good drainage.

Sharpen your blade at least once per season. Mulching blades are optional, but preferred. They chop blades of grass into smaller sections that break down faster.

Measure the output of your irrigation system to find how many inches per hour your system applies to the lawn. You will use this number when you calculate an irrigation schedule.

Step-by-Step Guide to Aeration & Topdressing

Aeration and topdressing have a direct impact on the health of your soil. These are the most important annual maintenance tasks for improving soggy soil.

Stage 1: Core Aeration

Cool-season grasses should be aerated in early spring or early fall. Warm-season grasses should be aerated in mid spring to early summer.

Step 1: Mow

Mow your lawn 1/2”-1” tall. Warm-season grasses can tolerate lower mowing heights, but cool-season grasses should be mowed taller.

Use a bag and remove as many clippings as possible. This will help to clear the soil for the aerator.

Step 2: Irrigate

When you aerate, the soil should be damp. If it’s too hard, the machine may not be able to remove as much soil. If it’s too wet, it will cause more compaction issues.

Water thoroughly 2-3 days before you intend to irrigate (less if you live in a dry or windy climate).

Step 3: Rent A Core Aerator

Go to a local hardware store and rent a mechanical core aerator. Look up the recommended depth and spacing for your turf species beforehand so you can choose a machine that will adjust to these settings.

Step 4: Adjust Settings

Adjust the depth, spacing, and core diameter (if possible) to the recommended settings for your turf species.

Step 5: Aerate

Follow the instructions for your specific machine. The cores should come out intact but crumbly. If the cores are too soft or too hard, stop aerating. Wait until the soil is damp.

Ensure your soil is damp before breaking out the aerator.

Step 6: Rake

With healthy soil, the cores are left to disintegrate and return to the topsoil. However, with clay soil, you should rake up and remove the cores, which leaves more room for the compost to penetrate into the root zone.

Throw cores in a compost pile or use them to fill low, inconspicuous areas of the lawn.

Stage 2: Topdressing

Aeration prepares the canvas, but topdressing is where the magic happens. Compost is the fairy godmother of soil problems. No matter what issue your soil may have, just sprinkle some magic compost on top and everything gets better.

Begin topdressing within 1-2 days of aeration.

Step 1: Order Compost

Use the formula to determine how much compost you need to apply to your lawn. Then, find a garden supply company near you and schedule a bulk delivery.

Although it’s possible to buy bagged compost for topdressing, this is only cost-effective in extremely small lawn spaces. Even with a delivery fee, bulk purchasing is generally much cheaper. Plus, you don’t have to go through the hassle of transportation or opening 50 plastic bags.

Step 2: Spread Compost

After treatment is the time to give your grass the food it needs. Source: TrimProLawns

Bring out that trusty rake- you’re about to get cozy.

Use a wheelbarrow, shovel, and rake to transport and spread compost across your lawn. This process may take a day or two, but try to finish before the holes dry out and get crumbly.

The goal is to fill the core holes with compost, but you will probably end up with compost on everything. That’s fine. It will settle when you water.

That’s it! Topdressing is pretty simple.

Step-by-Step Guide to Mowing & Irrigation Schedules

Aeration and topdressing directly improve the soil, but proper mowing and irrigation schedules will direct roots deeper into the soil and integrate compost further down into the soil profile.

This will help improve drainage and the overall health of your lawn.

Stage 3: Optimized Mowing Schedule

Mowing causes intentional stress on the turf, and the turf’s natural response to stress is to dig deep. Roots will grow deeper into the soil to access more water and nutrients to help the blades regrow.

Infrequent mowing can lead to weak root systems, which leads to a higher compaction rate in clay soils.

Step 1: Identify Optimal Mowing Height

Research the recommended mowing height for your turf species. Most warm-season grasses will be ½”-2 ½”, while most cool-season grasses will be 2”-4”.

Mowing height will change throughout the growing season.

Step 2: Identify Optimal Mowing Frequency

Research the recommended mowing frequency for your turf species. This will usually be 1-2 times per week, but it will change throughout the growing season.

Step 3: Create a Mowing Schedule

Use the recommended mowing height and frequency to create an annual mowing schedule for your lawn.

Step 4: Implement the Mowing Schedule

Once you have a mowing schedule, use it!

Stage 4: Optimized Irrigation Schedule

The final stage in improving your lawn’s drainage is consistent irrigation. Deep, infrequent irrigation will encourage roots to grow down towards moisture reserves. But, if you don’t water enough, your turf may suffer from drought stress.

Step 1: Identify Optimal Weekly Moisture

Research the recommended weekly irrigation rates for your turf species. This will vary depending on climate, but most species require ½”-2” per week.

This will change throughout the season.

Step 2: Calculate Irrigation Duration

Once you calculate the hourly output for your irrigation system/method, you can calculate how long you should water.

If your lawn needs 1” per week, and your system lets out .5”/hour, then you need to water for a total of 2 hours per week. Use a rain gauge and deduct rainfall when appropriate.

Step 3: Create an Irrigation Schedule

Divide the total amount of time you need to water into 1-2 watering sessions per week. The rule for irrigation is deep & infrequent; the less often you water, the more likely the roots will grow deeper to access water reserves.

Infrequent irrigation also allows your soil to dry out between watering, which will prevent that sludgy, sloppy mess we’re trying to solve.

Step 4: Implement the Irrigation Schedule

Follow your irrigation schedule! Water early in the morning to give plants time to absorb moisture before it begins to evaporate.

If in doubt, let the soil dry out. It’s always best for plants to be a little drought stressed rather than a little overwatered.


Mucky, muddy lawns are a pain. Luckily, there’s a tried-and-true solution.

Implement annual maintenance tasks like core aeration and topdressing to add organic matter into the root zone. This will improve porosity, which improves drainage.

Implement a customized mowing and irrigation schedule for your specific turf species. This will promote deep, fibrous root growth, which incorporates compost deeper into the soil profile and creates a healthy, lush lawn.

Thanks for reading- now get out there and get your hands dirty!

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