There’s nothing worse than getting ready to plant your seeds or seedlings only to find that the soil in your beds has become hard and compacted and is less than ideal for planting. Despite your best efforts, no trowel or dibbler is getting through that tough soil.
So, how do you fix this?
The best ways to fix compacted soil in your garden beds is to aerate the soil with a broadfork or digging fork, add mulch to retain moisture, add organic matter, and add worms to help break down the organic matter and create healthy and fluffy soil.
I’ll also share some common mistakes that you might be making to cause your soil to become more compact as well as the best cover crops to plant to prevent soil compaction in the next season.
Why is soil compaction bad?
When your soil is compacted, it means that there is little to no pore space left in the soil. Without pore space, plants have nowhere to spread their roots and can’t get oxygen from the soil.
When plants can’t spread their roots, their growth is ultimately stunted as they no longer have the ability to take in any nutrients or water from the soil. Similarly, soil that is heavily compacted probably can’t hold nutrients anyway.
Compaction also severely decreases the soil’s ability to take in and hold water. If you notice places in your garden where water just sort of sits on the surface instead of absorbing into the ground, there’s a chance that the soil may be compacted in these places.
What causes soil compaction?
Soil compaction can happen to the best of us and is a natural occurrence over time. But there are some common mistakes you might be making that are speeding up this process and making it worse.
Walking on the beds
The most common cause of compacted soil is foot traffic. Walking back and forth over beds where we plan to put our plants will press the soil down more and more over time. For those of you with much larger gardens, the same thing applies to vehicles as well.
Making sure you have walkways throughout your garden and have beds that are easily accessible is crucial to keeping soil compaction to a minimum.
Leaving soil exposed
Having bare soil is a quick way for your soil to end up hard and compacted. Throughout the season, the topsoil will dry out as it is continuously exposed to the sun, creating a hard crust on the surface.
An easy way to prevent this from happening is to plant cover crops. Cover crops do exactly what they sound like and cover the soil so that it’s not exposed. I’ll talk more in-depth about cover cropping later on.
Heavy clay soils
Soil is made of three different-sized particles: sand, silt, and clay. Sand is the largest of these 3 particles, clay is the smallest, and silt falls in the middle. For growing plants, you want your soil to have a good mix of sand, silt, and clay. This is called loam.
Soil that is largely made up of clay is much more likely to become compacted. For my fellow southern U.S. growers out there, we know this reality all too well. As clay soils get wet, the particles will stick together causing compaction.
But don’t let this scare you. It’s not impossible to grow in clay soils and the methods below will help make your clay soil workable.
It’s also important to note that while having soil with a heavy clay content happens naturally and isn’t a result of any mistake you made as a gardener, it’s always good to pay attention to your soil composition so you know exactly what you’re working with.
How to fix compacted soil
Having compacted soil can be stressful for any gardener but here are some things you can do to restore the soil to its former healthy and fluffy self.
Aerate the soil
The quickest way to create space and aerate the soil is to break it up yourself. For some, this may look like tilling. But be very careful with this. Tilling at the wrong time (i.e. when the soil is too wet or too dry) can actually make your soil compaction problem worse!
My suggestion would be to till only once as a way to “break ground” in an area that may be severely compacted or that has never been planted before.
I’m a not-till gardener myself so when my soil is compacted, my first move is to try and break it up a bit with a broadfork or digging fork. Broadforks are great because they can fluff up your soil without disturbing the organic matter and microorganisms that are crucial to soil ecology.
Digging forks work well for this too but they don’t cover as much ground and therefore are not quite as efficient as the broadfork in my opinion. But if you’re working with a much smaller space, digging forks may be a great option for you.
Mulching
Mulching is a great way to keep moisture in the soil and return organic matter to it as well. My preferred method of mulch is to use straw mulch but you can use other things you may have available like grass clippings, wood chips, or dead leaves.
I like to spread straw mulch about 2 inches thick over my beds. You can do this during the season while your crops are growing as a great weed suppressant and you can also do it at the end of the season to cover your beds and keep the soil from being exposed.
Mulching isn’t a substitute for cover cropping as it won’t add important nutrients to the soil like nitrogen. But, mulching can be a way to add some great organic matter to the soil which will ultimately help keep it from becoming compacted.
Add worms
Any gardener knows that having earthworms in the soil is a sign of healthy soil. Worms are cool because they work to break down organic matter (like the mulch we just talked about) and turn it into beautiful soil.
Because they move around so much, they’re constantly creating underground pathways which in turn, naturally aerate the soil and break up compaction.
But you can’t just throw some worms onto your compacted soil and hope that they’ll do the work for you. If the soil is too dry and compacted, the worms will die. To prevent this from happening, consider adding a layer of compost on top of the beds that need the help and add the worms to this compost layer.
You can buy good earthworms for your soil online from places like Uncle Jim’s Worm Farm or at a local garden supply store.
Prevent soil compaction next year with cover crops
Once you’ve gotten your soil to a place where it’s not quite as hard and compacted, you want to make sure that it stays this way. Cover cropping is one of the best ways to do that.
You can plant crops like daikon radishes that grow up to 18 inches long and penetrate deep into the soil. It’s a natural aeration method and also provides you with a great edible vegetable.
Sunflowers can also be a surprisingly good cover crop. Their large taproot can penetrate deep into the soil and bring up nutrients that may not be as readily available closer to the surface of the soil.
Other common cover crops include rye, alfalfa, clover, and oats. By planting these cover crops in late summer and leaving them until spring rolls around, you give them a chance to work their magic and add important nutrients back into the soil.
Once you’re ready to plant veggies or flowers in your beds, you can crimp or cut back your cover crops and leave them on the beds to break down into organic matter. This organic matter will help significantly in fluffing up your soil.
Have patience
But the key to restoring any soil is to have patience. Fixing compacted soil doesn’t happen overnight and may require a bit of trial and error until you finally get your soil where you want it.
This may mean you have to plant some things in containers this season while the soil in your beds works to heal and improve itself. Just know that your efforts will be well worth it in the end and your garden will thank you.
In Summary
Struggling to grow crops in your garden due to soil compaction is hard on any gardener. Luckily, there are ways to fix this problem and improve the overall quality of your soil for seasons to come.
To recap, here are the best methods to fix compacted soil in your garden:
- Aerate your soil by broadforking or tilling if necessary.
- Mulch the soil to improve moisture retention and add organic matter to the soil.
- Add worms to the soil to create natural aeration and help with the decomposition of organic matter.
- Plant cover crops as a way to maintain soil health and prevent compaction for seasons to come.
Use these methods and your soil will be brought back to life in no time.
