What To Add To A Vegetable Garden To Break Up The Clay

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Hard, dense, compacted clay soil types can be a nightmare to get a shovel through, let alone raise healthy plants in. There's no reason to give up on your garden just because of a little stubborn dirt, though. Wait to aerate your clay soil until it's thoroughly dry or wet, when it will be at its most manageable. Then, follow up by working in a quality amendment like compost, biochar, or manure to make it more hospitable for emerging plant life. It's not an overnight fix, but it's faster than waiting for traditional solutions like repeated applications of gypsum to get the job done.

1
Wait to aerate your soil until it's completely wet or dry. Since one of the biggest problems with clay soil is poor drainage, it's most difficult to work with when the ground is partially damp. Hold off on turning the soil until it either dries out to the point of cracking or softens up enough to get your shovel or tiller through easily.^[1]
- The fall months are a good time to aerate your soil, as conditions tend to be drier.^[2]
- If you attempt to work clay soil while it's still wet, you'll most likely just end up with a sticky, impenetrable mess on your hands (and shovel).
2
Turn the soil thoroughly before adding your amendment of choice. Thrust the tip of the shovel or trowel blade into the ground, scooping up a small amount of soil as you pull it back out. Repeat this churning action over every part of your garden where you intend to put down plants. You can turn your soil as often as needed, provided you follow up with an application of high-quality amendments, or materials used to condition the soil and improve its physical properties.^[3]
- Avoid working your soil without adding amendments immediately afterwards. Doing so will only cause you to end up with a mass of oversized soil clumps that are still unsuitable for planting.^[4]
- You can also use a push tiller to cover more ground in less time, if you have one.^[5]
Tip: Manual aeration will break up hard, compacted patches of clay soil, introduce air and other gases from the environment, and make it easier for your amendments to find their way deeper beneath the surface.
3
Remove any large rocks you come across. If you happen to uncover a pocket of large rocks while working your soil, stop and pull them out by hand. Rocks are a pain for many reasons—they act as a barrier for water, take up valuable space that could be used to incorporate nutrient-rich amendments, and can even damage your aeration tools if they make contact at just the right angle.^[6]
- Make it a point to remove all rocks bigger than about 6–8 inches (15–20 cm) in diameter.
- Rather than just discarding the rocks you find, you might use them to build a small retaining wall, ring a pond, or line an outdoor walkway.^[7]

1
Work organic compost into your freshly-turned soil. After loosening surface of the soil, pile on 2–3 inches (5.1–7.6 cm) of compost and use your shovel to spread it around until it's distributed evenly. Compost comes highly recommended by experienced gardeners for improving clay soil due to its soft texture and abundance of organic nutrients.^[8]
- Not only will compost introduce vital nutrients to the soil to feed your plants, the decaying plant matter will also help break up the clay particulate surrounding them.^[9]
- Consider starting your own compost heap or bin somewhere near your garden. That way, you'll always have a ready supply on hand.
2
Add 1 pound (450 g) of biochar for every 10 pounds (4.5 kg) of soil. The term "biochar" refers to organic material that's been burnt at a low temperature to form charcoal. Charred plant matter has a light, porous structure that's perfect for promoting drainage while also infusing a generous amount of healthy carbon and nitrogen into the soil.^[10]
- You can make your own biochar at home by slow-burning sticks, leaves, weeds, and other brush under a thin layer of soil, then collecting the remnants.^[11]
- The ashes from your fireplace, fire pit, or wood burning stove can also the serve many of the same functions as biochar.
3
Spread manure over planned planting sites that are lacking in nutrients. As you probably already know, manure is one of the best fertilizers there is. Like compost and biochar, it's useful for filling dense soil with beneficial organic compounds, but it may also be cheaper and more accessible if you own livestock or grazing animals, or know someone who does.
- Purchase bags of manure at your local gardening center or plant nursery, or ask a friend who keeps animals if they would be willing to share a portion of their stock with you.
4
Use a commercial soil conditioner as a quick and easy alternative. If you don't feel like going to the trouble of amassing your own organic matter, another option is to simply buy a few bags of perlite, greensand, or a similar soil conditioner. Fold these products into your soil the way you would any other amendment, making sure to use no more than the amount specified on the product packaging.^[12]
- Soil conditioners are specially formulated to deliver micronutrients to poor-quality soil while creating tiny channels to encourage runoff.
Warning: Contrary to popular belief, adding gypsum to clay soil isn't always a good idea. It's possible for gypsum to leach key nutrients like iron and manganese, leading to nutrient deficiencies that can slow the growth of your plants.^[13]

1
Bring in a new layer of topsoil if your plants are struggling. Even after loosening the compacted soil and adding amendments, you may discover that your plants are growing slowly or not at all. One immediate solution is to purchase a fresh supply of topsoil from your local gardening center and lay it down over the clay. You can then transfer your plants to the new soil, where they'll be exposed to better growing conditions.^[14]
- You can also haul over healthy topsoil from another part of your yard or garden to cover patches of clay soil in prime growing areas.
- Another benefit of putting down new topsoil is that it will gradually filter into the clay, acting as its own amendment and improving the quality of the underlying soil over time.
2
Plant cover crops to protect your soil during the off season. After you've harvested your fruits and vegetables or your flowering plants have entered dormancy, use your vacant beds to sew small grazing crops like alfalfa, clover, or buckwheat. These plants will improve your soil's physical properties by filling up space, introducing new organic materials, and keeping it dry.^[15]
- Other cover crops include field peas, hairy vetch, and cereal grains like rye, barley, and millet.^[16]
Tip: Be sure to pick out species that will fare well in the climate where you live. They won't do you much good if they die off a few short weeks after planting.
3
Build a raised garden or flower bed if you're still not having any luck. There's no guarantee that your clay soil will ever produce the kind of flourishing plant life you'd like. If all of your previous efforts have failed, a few raised beds may be just what you need. Growing your plants on top of the bad soil rather than in it will allow you to make use of your existing garden space without the need for a lot of time-consuming aeration or amendment applications.^[17]
- You can buy premade, ready-to-install beds at any major gardening center, or make your own out of scrap lumber, stones, plastic containers, or wooden crates.
- Raised beds can be used to cultivate all of the same sorts of plants you would grow in open soil. Due to their inherent size limitations, however, it's best to reserve one or two species to a single bed.

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Things You'll Need

Shovel or hand trowel
Compost, biochar, manure, or other organic amendment material
Push tiller (optional)
Commercial soil conditioner (optional)
Replacement topsoil (optional)
Building supplies for raised garden beds (optional)

About This Article

Article Summary X

By aerating your clay soil and adding an amendment, you can break it down fast and encourage new growth. Wait until the ground's completely wet or dry, since it'll be harder to work with soil that's partially damp. Then, turn your soil by digging up small amounts where you want to put plants to aerate it. Or, use a push tiller to save you time. Once you've turned the soil, mix in an amendment, like compost, biochar, manure, or a commercial soil conditioner, to add some extra nutrients. If your plants still struggle to grow, lay an extra layer of topsoil over the clay. For more tips, including how to make your own biochar from garden waste, read on!

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