How To Improve Clay Soil In 6 Steps
Last Updated by Amy
Heavy clay soil can frustrate even the most optimistic gardener. Follow this 6-step plan to improve soil structure and drainage so you can garden with ease and grow crops that thrive.
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The compacted, hardpan dirt in my first yard was a despicable pass for soil.
The builders scraped off the topsoil when they built the home in 1955, and after the clay subsoil was nice and compacted by construction machinery, they placed sod right on top of it.
During a rain, water hit the hardpan clay soil like pavement and quickly sheeted away, unable to soak in and irrigate the lawn or hydrate the soil organisms below.
In the backyard, previous homeowners filled in the swimming pool with low-quality, heavy clay construction fill. Not only did I find blue-painted chunks of concrete when I tried to dig, the thought of trying to put a shovel into the clay sent shivers down my spine!
I wasnt sure how to create a healthy, productive garden without back-breaking labor to improve my situation. It seemed hopeless.
I added organic matter in large amounts, but the clay soil just seemed to swallow it up without showing any signs of improvement.
I figured there had to be a better way, so I started researching how to transform my hardpan dirt into rich, loamy-clay soil the way nature might do it. My research led me to a combination of steps that totally worked, and Im excited to share them.
Amend The Soil With Compost
Add organic matter to improve drainage in poorly drained soils. Incorporating organic matter, such as compost, improves soil structure in poorly drained soils by increasing soil aggregation. Soil aggregates are groups of soil particles. The space between the aggregates provides pore space for holding and exchanging air and water. Adding organic matter is also ideal for improving very well-drained soils. Incorporating organic matter into sharply drained soils improves the water, air, and nutrient holding capacity.
Spread compost 2 to 4 inches thick over the soil surface and work it into the top 6 to 12 inches of soil by spading with a shovel or garden fork or through tillage. Do not over till. Using a rototiller too much or too frequently breaks down soil aggregates.
How Does The Type Of Plant Youre Growing Affect How Much Drainage Your Soil Needs
The type of plant youre growing will affect how much drainage your soil needs. Some plants, such as succulents, cacti, and other desert plants, need very little water and can tolerate dry, compacted soils.
Other plants need moist soils with good drainages, such as ferns and other moisture-loving plants. If youre unsure how much drainage your plant needs, check the label or ask a nursery employee.
When in doubt, its always better to err on the side of too much drainage. Soils with good drainage are less likely to waterlog your plants and kill them. If you have any questions or concerns about your soil, contact a local soil expert.
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How Can You Tell If Your Soil Is Well Drained Or Not
Most plants require well-drained soil to thrive. This means that the soil must be able to quickly remove excess water. If the soil is too dense or has poor drainage, the roots of plants can become waterlogged, leading to disease and death.
There are a few simple ways to test your soil drainage. First, dig a small hole in the ground and fill it with water. If the water drains away within a few minutes, the soil is well-drained. If the water takes longer than an hour to drain, the soil may be too dense or have poor drainage.
Another way to test drainage is to take a handful of soil and squeeze it into a ball. If the ball holds together and does not crumble, the soil is too dense. Good drainage is essential for plant health, so testing your soil before planting anything.
In general, well-drained soil is loose and free-flowing, while poorly-drained soil is dense and compacted.
What Does It Mean To Have Well
Well-drained soil is soil that allows water to drain at a moderate rate without water pooling and puddling.
This soil does not drain too quickly or too slowly.
Rather, it allows the plants to absorb the water.
If water drains too quickly, the plant will be dehydrated and die.
If the water drains too slowly, then the plants are left in water and are unable to get oxygen from the soil.
As a result, the plants will also die.
Plants that have insufficient water are more susceptible to disease and insect damage.
Ensuring your plants are in well-drained soil is essential to their health.
In particular, compacted and clay soil can both drain poorly.
If you have either of these soil types, then its important to amend them to make them more porous.
You can also choose plants that tolerate wet areas.
Sandy soil can also be problematic as it drains water away from plant roots too quickly.
If youre attempting to plant in an area with sandy soil, youll either need to amend the soil or choose plants that have the ability to tolerate dry and drought-like conditions.
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The Good And The Bad Of Clay Soil
Of all the different soil types , clay soil is made up of the smallest and densest particles. These small and dense particles can cause drainage problems and become compacted easily. However, clay can also hold onto nutrients.
So, all is not lost, we just need to manage it properly!
Lets look at how to transform that solid, waterlogged soil into a rich, loamy clay that is just right for planting.
Soil Drainage Method #: Use Additives
The fifth and final way to improve soil drainage is to use additives in your soil. There are a few different additives that will make your soil drain better and also help with nutrition.
Organic Material
Organic material is the most common and well-known additive to improve soil drainage. Soil drains better when it contains more organic material, such as compost, manure, and mulch.
Making compost can take months, depending on how much help the pile has from bacteria and worms. However, it is a great way to recycle yard and kitchen scraps, including:
- grass clippings
- fruit or vegetable scraps
You can even use wood ash, paper, cardboard, and many other materials to make your compost. If you are ambitious and have a large garden, you can ask friends, neighbors, or local landscapers if they have extra material you can use for composting.
For more information, check out my article on how to make compost, as well as my article on where to get manure, and my article on mulch vs compost.
There are lots of ways to find fresh or aged manure for your garden For example, you can find bags of Black Kow manure online from Ace Hardware.
You can also source manure from a friend who keeps chickens, or from a local business that boards horses or raises cows.
You can create your own leaf mulch by going over fallen leaves with your lawnmower.
Sand, Gypsum, or Limestone
Gypsum and lime both help to improve drainage, in addition to providing extra calcium for your soil.
Volcanic Rock
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What Are The Elements Used For Potting Soil And Mix
Potting soil and potting mix contain a mixture of perlite, sand, fertilizer, vermiculite, wood chips, and rocks. These coarse materials permit water and oxygen to flow and lets the roots spread.
- Perlite
Perlite is small, white rock that can soak up nutrients and water. Meanwhile, it is very lightweight, which stops the soil from weighing down.
Furthermore, the round balls occupy quite some space, thus making the soil breathable. Additionally, the stones can retain moisture which keeps the soils temperature in check and prevents cracking.
- Sand
Sand particles are tiny and coarse, making them the most economical option for good drainage. In addition, the small particles maneuvers between the soil and prevents it from clumping and, in return, allows for unrestricted water movement.
- Fertilizer
Fertilizers not only provide nutrients to the soil but can retain moisture too. As a result, they can absorb any excess water from the soil and halt excess water pooling.
- Vermiculite
It is another type of small stone-like material too. It can soak up water and make the soil flaky. When it is integrated with other materials like perlite and compost, it is a recipe for success as this combination can make inhabitable soil usable and good.
- Wood chips
Wood chips are a great organic material to add to the soil. It can decompose over time and release nutrients to the soil, making it fertile and healthy.
- Rocks
Final Words
Soil Draining: How To Make Your Soil Drain Better
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Creating well draining soil is fairly easy and involves only a few ingredients. The idea is to allow air spaces for the plant roots to receive nutrients and water.
The reason plants thrive with properly draining soil is because this extra space allows for soil aeration. This means that oxygen can move throughout the soil and around the plant roots.
Without oxygenated soil, such as with soil compaction, plant roots cannot receive important nutrients from the soil. They suffocate without the oxygen for nutrient exchange.
If you overwater compacted soil or have soggy soil, then your living plant roots will develop root rot. They will be drowned of oxygen and unable to receive important nutrients.
The exciting part is that healthy plants will grow much faster in aerated soil with proper drainage.
You got a little plant that just wont grow?
Improving soil drainage in your potted friend may do just the trick.
Soil Drainage Method #: Install A Drainage System
Another way to improve soil drainage is to install a drainage system. A drainage system can be as simple as a single pipe on a slope, or it can be much more involved.
The idea is to move excess water away from your garden by directing it with drains, pipes, and other channels, either above or below ground.
It may take some digging, but a good first step is to create a slight incline away from your garden so that excess water flows away from it on all sides.
If you want to take more direct control of the water , you can dig a channel. Then, either fill it with a pipe or with gravel .
Dont install a drainage pipe without at least a slight incline. Otherwise, the water will just sit inside the pipe, and it may even flow back into your garden!
Also, be courteous to your neighbors. Talk to them first to discuss any drainage problems, and dont send water into their yards.
Plants That Cannot Grow In Clay
Poor drainage can lead to waterlogged groundnot ideal for plant growth.
Add Worms To Your Soil
These little beings are part of the worldwide soil food web. You can add mulch to your soil, and then introduce worms if you have an outdoor garden. If you are adding organic matter to your potting mixes, then just mix a bit of mulch or compost into it. It softens the soil and also will be great for beneficial garden insects and worms to feed off of.
Add Organic Materials To Your Soil
Adding organic material can be a simple way to naturally improve soil drainage & increase water holding capacity. You can add manure as well as add compost or mulch. Mulch helps to retain water, and decomposes slowly. It will also help protect the roots of your plants against weeds and during temperature changes. Soil drains a lot better with soft, decomposing materials such as compost or mulch. It might take you a while to create your own compost, but it is definitely worth the wait. Organic matter acts as a sponge and will keep the soil moist.
In the meantime, while you wait for your homemade compost you can also add perlite, sand & vermiculite to your soil.
Perlite is a volcanic rock that helps loosen soil, prevents it from creating clumps and improves drainage. Sand will also help prevent clumps and help with root development. Vermiculite is also volcanic rock, and you can make or buy a mix of all three of these ingredients for better draining soil. Your plants will thrive and grow to new heights!
Improve Soil Drainage In Your Garden
Along with roots sitting in wet soil, compacted soil that doesnt drain well can also contribute to run off meaning water doesnt get absorbed at all. Plant roots can also be starved of oxygen if the soil is compacted. Sand is a good and cheap way to improve drainage. Incorporating it into your garden soil will help break it up and help aerate for healthier roots. Many hard soils have little organic matter, so adding in some well-rotted organic compost such as manure or garden compost helps break down clumps of soil and provides nutrients needed for your plants to grow. Soil conditioners can also help or try green manure and leaf mulch.
How To Create Soil That Drains Well
Digging organic matter into your existing soil is one of the best things you can do to improve soil drainage. This simple fix works for almost any soil that drains too fast or slowly. For an unplanted bed, spread 3-4 inches of your organic matter across the surface of the soil and work it into the top 8-12 inches . For a bed that is already planted, add a couple of inches of compost to the soil surface each year and over time, nature will do the mixing.
If you’d rather avoid lots of digging or want a quicker solution, raised beds are the answer. The beds should be at least 6-8 inches above the existing soil level. You can purchase or build raised beds out of many different materials and size them to suit your needs. Recipes abound for soil mixes for raised beds, but they are basically combinations of high-quality topsoil and compost or other well-decomposed organic matter.
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Creating well-draining soil in pots is similar. You can either buy bagged potting mix, or make your own blend. It’s best not to use soil from your garden in containers, no matter how well-drained. It tends to be too heavy and can contain weed seeds and pets that could cause problems later.
The Concept Of Perched Water Table In Pots
As Ive mentioned earlier, in gardening, especially container gardening, you will often run into a phenomenon called a ‘Perched Water Table’ .
So what is PWT and how does it form?
This is a common scientific phenomenon known to scientist. But it is a foreign subject to most gardeners despite the fact that it affects them every day.
Im going to explain this concept in the context of container gardening.
Lets find out:
When watering your container plants, you might notice some sogginess at the bottom of the pot.
This water that doesnt drain as intended is what we call PWT.
How does PWT then form?
The image below illustrates the formation process of a perched water table in pots.
Dont mind my mediocre drawing because Ill explain exactly whats happening.
Ill get a bit scientific but will try to explain as simply as possible.
First, lets start with the basics:
Your favorite potting mix or growing media holds water by means of two natural forces.
The first force is through adhesion and the second one, cohesion.
These two forces are generally referred to as Matric Potential or generally explained as water potential. Simply put
Adhesion + Cohesion = Matric Potential
MP is responsible for retaining water within the pot so that the moisture is available to the roots.
You should also note that MP is always uniform within the entire container.
We call this force gravity.
Now, heres the catch:
Its called the perched water table .
Thats it!
I hope Ive not lost you.
Improving Clay Soil And Using Gypsum To Improve Soils
- Most Maryland soils are made up of mineral particles- sand, silt, and clay organic matter and air and water- pore spaces . Soils are classified largely by their texture and that is determined by the relative amounts of sand, silt, and clay.
- Clay gets a bad rap, but it is an important constituent of soil because it holds nutrients and water. But too much clay can cause problems.
- Soils high in clay feel sticky, dont drain well, and become rock hard when dry. You cant change the texture of your soil but you can improve soil structure .
- Adding lots of organic matter such as compost, farm manure, or shredded leaves to clayey soil will allow it to drain more easily and hold the right amounts of water and air for better plant growth and increased biological activity. Adding sand can be tricky and typically is not recommended to be added to clay soil.
- Gypsum is calcium sulfate and is often recommended as a ‘clay buster’. Despite what the bag proclaims, there is no scientific evidence that it can improve the structure of Maryland soils. It is a good source of soluble sulfur and calcium and can be useful to add to soils that are low in these two nutrients and are in the correct pH range