How to Help Drainage in Clay Soil?

Clay is important to the overall composition of soil but an overabundance of clay prevents water from draining correctly. This can cause pooling as well as plant rot. Solutions exist to fix the drainage issue but you will need to do some testing and work to fix drainage in clay. 

There are two basic ways how to help drainage in clay soil. You can add organic matter or you can install a drainage system. You may also do something other than planting your vegetables and plants in the clay too, such as utilizing raised garden beds. 

Read further for more information on the best ways to deal with a lot of clay in your soil. 

The Composition of Soil

Soil should have some clay in it. Clay can help retain water and nutrients. That can be helpful if there is a drought or at a time when the drainage system works well. Clay is also plentiful in nutrients, which benefits all plants if the drainage is corrected.

The downside of clay holding water is that the water fills up all the air spaces in the clay and that pushes out air that plants need for their roots.

You shouldn’t have more than 50 percent of clay in the soil. There should be topsoil on the top layer with clay further down. A reduction of topsoil, no topsoil at all, or too much clay will make the dirt feel sticky. It becomes hard when it’s dry and doesn’t drain. 

Read: Are Rocks Better Than Mulch?

Testing Your Soil

Two simple tests can give you an indication of where your soil lies on the composition scale. One way is to dig up a little soil and squeeze it in your hand to form a little ball. Soil that is easy to mold, smooth, and sticky is heavy with clay. 

Soil that tends to fall apart and has a coarser texture has less clay. 

The next thing to look at with your soil sample is the color. Poor drainage is indicated with gray clay while red soil shows the dirt is high in iron and has good drainage.

You can test how well your soil drains before trying to plant. That will involve digging.

First, dig a hole that’s 12-inches in diameter and 12-inches deep. Fill with water and fill it again the next day. 

It should take no more than eight hours for all the water to drain out the second day. Holes where the water drains less than 1 inch an hour mean bad drainage. That could be because of high clay content in the soil, compacted soil, or another problem like a high water table or buried debris. 

You should test your soil to find out the percentage of clay and the pH. You can get a soil test kit at the local agricultural extension office. The test will show you the pH as well as nutrient content. It will also have advice for soil supplements in the results. 

A soil’s pH should fall between 6.3 and 6.8 for most plants used in landscaping to thrive.Improving Your Clay Soil

Read: How Much Does It Cost To Redo A Backyard?

Add Organic Material

The easiest thing to do to improve the health and nutrients of your clay soil is to add organic material to it. Garden compost is the most recommended but you can also use farmyard manure, bagged manure products, and even seaweed. 

To add the organic material, spread the material container across the top of your soil and mix it in with a garden fork. You can also mix it with a tiller four to six inches down. You will need to adjust the thickness depending on what’s in the compost. 

Manure needs about a 3-inch thickness while dried seaweed should be applied 3 to 6 ounces per square yard. 

Organic matter should be applied over your garden beds in spring or fall. Cover the beds with mulch. You can use sawdust, wood chips, or bark on the surface to prevent erosion.

Read: Are Backyard Renovations Worth It?

Use Gypsum

Gypsum is another element that can change clay soil for the better. Gypsum releases heaving sodium into the clay soil, which helps clay drain more water. However, a white crust may develop when the soil is dry and that means it’s high in sodium and you shouldn’t add gypsum. 

It’s best to add one pound of gypsum for 5-square-feet of soil and then mix it into the top three inches of soil. You may need to add it again eventually because gypsum only offers a temporary solution. 

Installing Drainage

The last resort is to install drainage to help your clay soil improve how it handles water. You can add an underground drainage pipe that moves water from the low part of your yard to outside your yard. 

A French drain is a popular option because they look nicer. These underground tunnels are filled with gravel and a perforated pipe that disperses water. 

You can also install a Herringbone drainage system. Dig deep trenches across the area that feed into a primary trench in a herringbone design. Cover the trench surfaces with small stones or gravel.

Lay pipe with drainage holes across the top in the trenches and connect them. Set the pipes where they flow into the main pipe. Finally, build a soak-away at the end of the main pipe. This should be a circular hole that’s six feet deep with sloping sides and filled with gravel. Cover it with thick plastic sheeting. 

Read: How Much Should I Spend On My Backyard?

Plants for Clay Soil

Some ground covers work well in clay soil to help improve the nutrients. Other plants that do well are:

  • Ivy
  • Peonies
  • Roses
  • Snowdrops

Plants that don’t do well in clay soils include:

  • Bulbs
  • Lilies
  • Sea hollies
  • Irises

Read: How Often To Replace Mulch?


What if I can’t get my clay soil to grow the plants I like?

One solution to grow vegetables and plants that require a different type of soil other than clay soil is to create raised flower beds. Then, you can completely control both the soil and the drainage. 

Is there a quick way to change my soil’s composition?

While you can’t fix clay-filled soil overnight, you can use certain materials that will change the soil content rather quickly. The best material to use for quick changes is compost. Composts that work the fastest are left mold, green plants, and well-rotted manure.

How will mulch help my clay soil?

Mulch is a great additive for yards with a lot of clay. It can be used in gardens but also should be put around trees and permanent plants to conserve moisture and help reduce summer heat.

Mulch will eventually decompose into the soil, adding vital nutrients that will also help overcome the disadvantages of clay.

Do I have to till my clay soil to add organic matter?

You don’t have to till the soil to mix organic matter into it, although tilling is the best way. You can use a garden fork, liquid aeration, dig and drop composting, and grass mulching. 

Remember that adding nutrients to your clay soil isn’t a one-time event. You will need to keep up with it once or twice a year to have good plantings and a healthy yard.

Do I have to install drainage to improve my clay soil water pooling issue?

Installing a drainage system is an option to fix water issues in clay soil but it isn’t the only solution. The first solution is to add organic matter to the soil.