Garden Maintenance

Gardening In Clay Soil

If you live in a newer neighbourhood or a newly built home, you likely have a lot of clay soil. Gardeners often believe they have to get rid of clay, or use raised garden beds. But is that true or can you garden in clay soil?

What Is Clay Soil

Clay is pretty easy to recognize when you hit it. If it’s dry, the outside looks cracked, and it’s rock hard. If it’s wet, it’s very dense. Clay retains its shape whether very wet or dry. It retains moisture for a long time, but when it does dry out, the top hardens like rock, and cracks form. When it’s wet, if you break it apart, you’ll be able to smooth the inside edge until it’s smooth and polished.

Dry cracked clay soil

Digging up clay soil is a lot of work. Be sure to use very sturdy tools, or prepare to buy a new shovel every few feet. It’s heavy and difficult to work.

Benefits of Clay Soil

Clay soil does have benefits. The first benefit is that it retains moisture and nutrients longer than other soil types. This is really great through drier summers. It allows us to water and fertilize less often.

Clay soil tends to be alkaline, this makes it easy to grow plants that prefer a specific (higher) pH.

During cold winters, wet (not boggy) clay offers extra protection to the roots of our plants. Wet soil maintains its temperature during colder weather better than dry soil. Because clay retains so much moisture, and has soil particles closer together it requires much colder temperatures before it freezes. In the winter, clay soil doesn’t freeze as deeply as silt (regular garden soil). This provides a lot of cold protection for your garden (this protection is amplified if we get good snow coverage).

Pitfalls of Clay Soil

All those benefits of clay soil? Yeah, they’re also the reasons why some gardeners dislike it.

Yes, clay retains moisture. But because it’s dirt particles are so small and close together, it’s easy to flood the garden because the water doesn’t absorb or drain. The opposite problem can also occur. If rain is hard, fast, and short lived, then it mostly runs off rather than getting absorbed into the ground.

shovel in dry dirt

Monitoring soil moisture is important. Too frequent watering can damage plants as much as not enough water. Mulch helps with water retention as well as providing weed control, and adds organic matter to the garden.

Yes, clay holds nutrients better than other types of dirt. But it also holds things like salt as well. It’s possible for plants to die from lack of nutrients’ even with adequate fertilization if a clay garden bed accumulates too much salt over the years.

Clay soil has fewer air pockets. This means roots quickly become water logged and drown if we don’t provide additional drainage.

Plants that prefer acidic soil don’t do as well in clay. If you wanted to grow blueberries or other plants that prefer acidic conditions, you’d need to pay careful attention to the pH, prepare the bed well in advance, and amend more often.

I find it helpful to track both pH and how often I amend so I learn how often my garden needs amending to stay healthy. A soil and amendment log is included in My Garden Journal & Planner:

Garden Journal & Planner

Planting In Clay Soil

When transplanting seedlings you can either dig a hole that’s a lot bigger than the plant you’re planting will become, then backfill with amended soil when you plant the seedling. Or you can dig a hole that’s just big enough for the seedling, make sure the roots are open, then stick it in the hole with little amending of the soil.

The benefit of digging the larger hole is that your plant will have easy to maintain soil that follows standard garden rules. It will establish itself quickly and usually do very well. This method offers greater plant flexibility because you don’t have the rigid conditions to work with. If you want to plant blueberries, this method would work best.

  1. The biggest draw back to this method is the cost. If you’re digging holes for trees and shrubs, you’ll need to dig massive holes and fill them with dirt. Unless you have a free supply of dirt, the cost will climb very quickly.
  2. You can still find yourself with an even more frequent boggy area when the water drainage from your perfectly amended garden hits the wall of clay around it.
  3. This is a back and shovel breaking method. Clay is heavy.
  4. If you don’t dig your hole big enough, you create a situation that basically becomes a root bound plant. It grows well in the lovely amended soil, but as soon as the roots hit clay, they wind themselves back in and around within he amended soil. Over time it doesn’t do as well as if it’d been planted in clay from the start.
person holding trowel with dirt.

The benefits to digging the smaller hole include:

  1. Easier. It’s so much easier to dig a small hole than a big one.
  2. Costs less.
  3. The plant’s roots grow into the clay instead of becoming root bound.
  4. No broken tools or aching backs.

But there are some drawbacks to this method. The most notable is that there will be certain plants that just don’t do well in clay, so you’d either need to replace them more often, or they wouldn’t grow as well.

A third method is to use raised garden beds and avoid the clay altogether. This allows the gardener better control of the growing environment, but can be cost and/or labour intensive to set up. If this method is used, it’s a good idea to note the natural drainage of your yard so you don’t create flood plains that could hurt your yard or home.

Plants that want well drained or acidic soil won’t like clay.

Which ever method you choose for your garden, you’ll have the most success if you plant according to the appropriate growing conditions preferred by your plants. If a plant wants well drained soil, then it usually won’t do well in clay.

Amending Clay Soil

Instead of digging out clay, it’s possible to amend your soil to adjust the composition and texture. Amending it creates more air space between the particles of soil, it allows better drainage, and is more versatile for growing different plants.

If you’re short on time, you can add sand to the clay, and work it in. You’ll need equal quantities of sand to clay. This method quickly adjusts the drainage and texture, but it can be very costly. It’s important to note that sand doesn’t hold nutrients very well, so even though it will be easier for roots to grow through, it won’t provide the same quality of nutrients as other methods. In general, I don’t recommend this method. But it is a fast place to start. Further amending would still be needed if this method is used.

If you’re willing to wait a growing season for your garden to amend itself, you’ll get more balanced and versatile soil as a result. You can do either of these methods, or a combination of both.

  • Work organic matter into the clay and let it break down naturally. You can use mulch, compost, or leaves.
  • Plant daikon radish and purposefully leave it to winter kill in the ground.
2 daikon radishes on wood fence boards between a cup with rock salt and a wood handled knife.

As it breaks down, it releases nutrients into the soil, but it also provides food for microorganisms to move into your garden. These microorganisms feast on the rotting roots, and further till and nourish your garden.

Daikon grows well in clay – even better when there’s some water. The long, thick root breaks apart the clay. The large leaves provide a living mulch the keeps many weeds at bay. In a single season it turns a clay garden into a diverse and thriving garden.

Is It Necessary To Amend Your Soil?

The answer to that question is really, ‘It depends.”

I’d invite you to consider the growing conditions your plants prefer and then decide whether you need, or want, to amend your soil. Most plants can adapt to growing in clay soil, but some won’t. Some need extra care in order to thrive.

It’s okay to amend some areas, but not others. If you want a blueberry patch but also want raspberries, amend the soil for blueberries, but leave the raspberries in clay. Most raspberries will thrive with little difficulty.

It’s possible to work with clay soil and grow in it too. It’s up to you whether you’ll stick to the limitations of clay, push the boundaries, or work around you clay by using raised beds or containers for certain plants.

Whichever method you choose, you don’t need to be limited by the soil your home comes with, most plants grow well in properly tended clay soil gardens.

Gardeners often believe they have to get rid of clay, or use raised garden beds, to have a healthy garden. But is that true or can you garden in clay soil?


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