If you’ve ever tried gardening in heavy clay soil, you know what a challenge it is. Digging is back-breaking work, and you might end up with plants that don’t grow very big or just struggle and die.
This doesn’t mean that clay soil is the worst thing ever. Clay actually has some benefits that are good for your plants and garden, but there’s no denying that it can be hard to work with.
Here’s more about what clay soil is, how to know when it’s time to “fix” your soil, and how to improve clay soil to make life and gardening easier on yourself!
What Is Clay Soil?
Even though we tend to label soil as “sandy” or “clay,” all soil is made up of a mixture of three different particles: sand, silt, and clay. Soil usually gets labeled based on which of these particles is the dominant one.
To help you get an idea of what clay soil is, here’s a look at the three different soil particles/types and the unique characteristics of each one:
- Sand– Sand particles are the largest of the three and have a rounded shape. They tend to stay separate, rather than sticking together, and provide excellent drainage and aeration because of this. However, they don’t hold onto nutrients very well, which makes sandy soils typically low in fertility.
- Clay– Clay particles are the smallest of the three and have a plate-like shape. They easily stick together and layer on top of each other, much like a stack of plates. This means clay can have drainage and aeration problems but is excellent at holding onto nutrients.
- Silt– Silt particles fall in between sand and clay for particle size and tends to have a spherical shape. They hold water well and release it easily to plants as needed.
Soil can be almost any mixture of these particles. Balanced soil that is made up of near equal amounts of each particle is referred to as loam soil. Slightly more sand would make a sandy loam and so on.
Clay soil is the bane of many gardeners because it’s hard to work with and tends to have poor drainage. The good news is that there are several things you can do to improve your clay soil.
Clay soil is usually defined as one that is made up of 40% or more of clay particles. Heavy clay typically has 50% or more clay particles.
How to Know If You Have Clay Soil
Many times it’s obvious that you have clay soil. It might get cracks on top when it dries out. Water might puddle instead of soaking in. You may have noticed that making holes is like trying to dig through concrete, or you get glue-like mud stuck to your shoes when it rains.
Other times, it isn’t as obvious, but there’s a simple test you can do at home to find out what your soil type is.
Take a handful of soil (try to get it without rocks and debris) and mix it with enough water to form a ball that sticks together. If you can’t get it to form a ball no matter how hard you try, you have sandy soil.
Once you have a ball formed, push it through your thumb and forefingers to make a ribbon. Keep pushing more through until your ribbon breaks, then measure the unbroken length.
If your ribbon measures at least 2 inches long or longer, you most definitely have clay soil. Anything between 1 and 2 inches long indicates a clay loam soil, which you may not need to improve it at all, or will take less effort to improve.
Most of the time, you’ll know if you have clay soil, but you can do a simple ribbon test at home to determine how much clay is actually there. The longer the ribbon you can form, the higher the amount of clay in your soil.
Benefits and Downsides of Clay Soil
Working with clay can be frustrating, but it’s not all bad. Here are the biggest pros and cons of clay soil.
- Holds water well
- Holds onto nutrients well and is usually very fertile
- Typically needs less irrigation and fertilizer
- Can be difficult to work with
- Often has poor drainage (especially heavy clay)
- Often has poor aeration
- Compacts easily
- Slower to warm up in the spring
- Tends to heave or crack
How to Make the Right Changes
If you find that the drawbacks of your clay soil are outweighing the benefits, it’s time to work at improving your soil. A big sign that your soil needs “fixed” is if you see plants struggling to thrive year after year.
When it comes to how to improve clay soil, your goal should be to keep some of the benefits of clay (like good water and nutrient retention) while still making it easier to work with and giving it better drainage.
Improving your soil can make a big difference to the plants in your garden. They’ll be able get more air and nutrients from the soil and won’t get waterlogged, resulting in a healthier garden.
To do this, you’ll need to have both short and long term strategies. Unless you want to ship in loads of perfect soil, the change won’t happen overnight, but you can see results pretty quickly.
One of the most important short-term steps to take is amending your soil with organic matter. From there, you can work on other strategies like implementing a no-till system or growing cover crops.
Here’s an in-depth look at each way to improve your clay soil for good.
Test Your Soil First
Even though this step is optional, it’s always better to get a soil test done before you start making changes. Getting your soil tested will tell you exactly what it’s lacking and give you guidance on what amendments to add.
For example, if you find out your soil is acidic and you want it to be closer to neutral, you can add in lime. Or if it’s the other way around, you can implement a few strategies to make your soil more acidic.
You can take some soil samples and send them off to your local ag extension office to get professional results and advice for a relatively low cost.
Another option is to buy your own soil testing kit and do it yourself at home. DIY testing kits won’t be quite as accurate or test for as many things, but you can still get a pretty good idea of what your soil is like before you start working on it.
Taking a sample of soil and getting it tested is the best way to learn more about your soil and what amendments you might need to add. You can either send it off to a lab or buy your own DIY soil kit.
How to Improve Clay Soil with Amendments
Amending with organic material is probably the single best way to improve clay soil. Adding organic matter improves soil structure, which means it will drain better, be easier to work with, and won’t get compacted as easily.
Many soil amendments also contain beneficial microorganisms that further help to break up clay and add more nutrients to your soil.
Here’s a look at the top options.
Gardeners love compost and with good reason. It’s basically broken down plant material that comes from food waste, dead garden plants, leaves, grass clippings, and more.
Compost is very rich in nutrients and one of the best ways to improve soil structure. It will lighten clay soil and give it better drainage and workability. It’s also rich in microorganisms that will further benefit your soil over time.
Another great thing about compost is that it can be free if you make it yourself at home. There are lots of ways to create a DIY compost bin where you can send a lot of food waste products instead of throwing them away.
Compost is at the top of the list as a way to improve clay soil. It improves drainage and soil aeration and will keep benefiting soil structure over time. You can build a compost bin of any size right in your backyard.
Depending on the area you’re trying to amend, you may not be able to make enough compost to cover it. If this is the case, look for a local company that sells compost in bulk.
Mushroom compost is frequently offered by landscaping companies, and some areas also have commercial compost suppliers that offer different types.
Check into your options and make sure to ask companies whether their compost contains any chemicals (pesticides, fertilizers, etc.) because you don’t want those in your soil.
Leaf mold is a specific type of compost. It simply consists of leaves that have decomposed for a year or two. You may not think much of leaves in relation to gardening, but leaf mold is actually compost gold in the gardening world.
If you can find a large amount of leaf compost, it will do wonders for clay soil. Some towns and cities that take away bags of leaves from residents will compost them. It would be worth finding out if you could buy any of the finished product.
If not, start making your leaf compost piles this year so that you can add your own to your soil in years to come!
Composting leaves makes one of the best versions of compost for your garden. It will benefit any type of soil but is especially good for amending clay.
Not everyone is thrilled with the thought of adding animal manure to their garden, but it can actually do a lot for improving clay soil. You can even make plant food out of it.
For the most part, you want to go with rotted manure over fresh manure, especially if you plan to plant your garden area soon. Not only has much of the smell gone away in well-rotted manure, the fresh stuff can release chemicals as it breaks down that won’t be good for your plants.
You can buy bags of manure from your local garden center, but check with a local farmer first. They would probably be happy to sell it to you at a low price (or even give it away!).
There are two things to be careful of with manure. First, it’s possible for manure (mainly from cows) to be contaminated with an herbicide that some farmers spray their hay fields with. If you buy from a farmer, ask about this issue before putting any manure in your garden.
Second, never apply manure before a hard rain or on frozen or waterlogged soil. This increases the potential for it to wash away and contaminate waterways.
Green manure isn’t really manure at all, meaning it doesn’t come from animals. It refers to things like grass clippings and other plant materials.
The difference between green manure and compost is that the plant material hasn’t broken down at all. It’s added to the soil while it’s still green (hence the name).
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Green manure can be very beneficial for improving clay soil, but it won’t have an immediate effect because the material still has to break down. Make sure you combine it with other amendments like compost and animal manure for the best results.
Worm castings are technically a type of manure, since they come from the waste products of earthworms. They are high in organic matter, including many beneficial nutrients.
Adding worm castings will improve the aeration and drainage of clay soil and make it more fertile. It’s also something you can make at home if you want to build your own worms bins. Otherwise, you can just buy it at the store.
Important Tips for Amending Clay Soil
Whichever amendments you choose, it’s important to go about amending your soil the right way. Just applying it to the top of your soil will not do very much overall.
First, you’ll need to decide which parts of your garden to work on first. Trying to improve a large area all at once can be overwhelming, so select smaller areas to begin with, perhaps where your favorite garden plants go.
Next, spread a 3-6 inch thick layer of your chosen amendments over the soil you want to improve. Make sure you have a sharp, sturdy garden shovel so that you can work what you just added 10-12 inches deep into the soil.
A sturdy shovel is a must for amending clay soil. It will be tough to work with at first but will get easier as you add more and more organic material.
It’s important to work your amendments deep into the soil because this is where the roots of your plants will try to grow.
If you are finding your soil to be impossible to work with, consider layering your amendments on your soil in late fall. Then, instead of working them in, let the cold, snow, rain, and freezing temperatures of winter do a lot of that work for you.
Utilize Cover Crops
Cover crops are another fairly simple way to improve clay soil. They have the name “cover crop” because they are crops that are grown for a purpose other than being eaten. Farmers and gardeners grow them to prevent erosion, add nutrients to the soil, and so on.
The reason cover crops are beneficial for clay soil is because they will send roots down that make little waterways for water to drain out and air to get through. They also enrich the soil and improve soil structure by being incorporated into the soil instead of harvested.
There are many cover crops you can grow, but nitrogen-fixing ones like hairy vetch and red clover can be particularly beneficial.
For heavy clay soil, you can try a cover crop like daikon radish that will grow thick roots several feet long and break up compaction. The best option, however, is to contact your local ag extension office for regional recommendations.
Nitrogen-fixing cover crops add nitrogen to your soil along with improving soil structure and adding green manure when you cut them down. Talk with a local expert to find the best cover crop options for your specific region and soil.
Whichever cover crop you choose, you’ll need to leave empty areas in your garden to plant it. Seed it at the appropriate time of year, and at the end of the season, incorporate it back into your soil as green manure.
Your soil will be much improved the year after planting the cover crop, and you can move on to other areas of your garden.
Go With Raised Beds
Sometimes, clay soil is just too much work to amend. Maybe you don’t have the physical strength to work with it, or it would take more time than you can afford.
If this is the case, one of the best ways to deal with clay soil is to build raised beds. Raised beds give you completely new soil to work with without going through the hassle of trying to fix your original soil.
What you’ll need to do is lay out a garden design and choose the materials for your raised beds. You can use lots of things for the sides, including wood, stone, large pavers, and even straw or hay bales.
Then, buy good quality soil in bulk to fill your raised beds with. Add a lot of compost and organic material to the beds along with the soil to ensure it will be the best possible for your plants.
Your plants will enjoy the benefits of not having to fight through clay soil with their roots, and you’ll also enjoy garden beds that are much easier to work with.
As an added benefit, raised beds can actually improve the soil underneath over time. It won’t happen right away, but the better soil and organic matter will eventually work their way down into the clay beneath, leaving it better than before.
Raised beds are a way to avoid working with clay soil. They’re an especially good choice if you have heavy clay or other challenges that would make amending your existing soil very difficult.
Aerate Clay Lawns
Clay soil can be just as difficult in lawn areas as it can be in garden areas. It’s much more likely to get compaction in lawn areas because there’s usually heavier foot traffic and heavy things like lawn mowers going over the soil.
Compacted clay soil becomes waterlogged easily and can make it difficult for grass roots to get air and nutrients.
If you’re struggling with clay soil in a lawn area, the best tactic is to aerate it once or twice a year.
Aerating your lawn just means putting holes in it that will allow water, air, and nutrients to get into the soil and excess water to drain out. You can use a plug coring aerator or something from your shed, like a pitchfork.
Use your chosen tool to poke evenly spaced holes as deep as possible. If you don’t want to do it yourself, most lawn companies offer this service.
Don’t Add Sand
Because sandy soils are basically the opposite of clay soils, it seems like it would make sense to amend clay soil with sand. However, this is not the case and can actually make your soil worse!
Adding sand is one of the first thoughts people have to improve clay soil, but sand and clay are not a good mix. Stick with compost and other organic materials to make your soil better.
Mixing sand into clay soils will create a concrete-like mess rather than improving your soil. Rather than trying to make soil more sandy, you want to focus on adding as much organic matter as possible, which is what will really improve soil structure.
Save yourself a headache and skip the sand!
Maintenance Tips for Improving Clay Soil
Once you’ve done the hard work of improving your clay soil, it might be tempting to just sit back and enjoy it. However, if you don’t do a few maintenance tricks, it will eventually end up reverting back to the way it was.
Here are the top ways to keep improving your soil every year:
- Topdress soil each year with organic matter– Always remember that organic matter is the key to improving clay soil! When you first amended your soil, you should have worked the organic material about a foot deep into your soil. Maintaining your soil is easier because all you need to do is apply a 1-3 inch layer of organic matter on top of your soil every year. No need to work it in, but keep regularly applying it!
- Avoid tilling and compacting your soil– Compacting your soil is a major problem if you’re dealing with clay. It can destroy years of hard work spent improving soil texture. Tilling may seem like it aerates soil, but it actually leads to more compaction because you’re breaking up the soil structure.
Tilling may seem like it loosens your soil up, but it actually leads to more compaction. After the first time you work amendments deep into the soil, avoid tilling and walking on garden areas to avoid compaction.
After working your amendments deep into the soil the first time around, avoid tilling and walking on your soil as much as possible. Try a minimal or no-till gardening system to keep your clay soil improving.
- Use natural mulches– Mulch is favored by many gardeners to keep weeds down and to help the soil retain moisture. Clay soil is less likely to need mulch because it already retains moisture well, but if you do want to mulch, use a natural type that will break down and add more organic matter to your soil over time.
- Test your soil occasionally– It’s a good idea to test your soil every 2-3 years to check whether it’s improving or holding steady. A regular soil test will help you stay on track with maintenance and let you know if there are any other amendments you need to add.
Get to Work on Your Clay Soil
Now that you know how to improve clay soil, it’s time to get to work! As you can see, there are many methods for improving your soil, so there’s no need to despair if you’ve gotten tired of dealing with clay.
Work in amendments, use cover crops, add raised beds, and keep up with a few maintenance tasks to get your soil into better shape! After all your hard work, you’ll be able to enjoy the best vegetable garden you ever had or do your landscaping with ease.
Jen is a master gardener, interior designer and home improvement expert. She has completed many home improvement, decor and remodeling projects with her family over the past 10 years on their 4,500 sf Victorian house. She is also a passionate farmer who keeps goats, chickens, turkeys cows and pigs on her farm, and an instructor for her community’s Organic and Sustainable Farming project.