The question at hand is about the best method for preparing garden soil: digging once or twice to improve its structure.

The question at hand is about the best method for preparing garden soil: digging once or twice to improve its structure.

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Digging or no-digging the garden soil isn't a straightforward yes or no question. Embrace the no-till method, often favored by us and gardeners alike, as it's generally better for soil life. However, there are instances where digging could be beneficial, including double digging.

Let's dive into this gardening topic from a gardening perspective, uncomplicated and straightforward.

Soil Stratification: In Depth

Soil, as we know it in our yards, consists of topsoil and subsoil or undersoil. The topsoil, usually referred to as garden soil, is what we gardeners focus on. This is the soil we grow plants in.

We strive to build a substantial amount of topsoil atop the subsoil – often called "building good soil."

The subsoil or undersoil lies beneath the topsoil. It generally has a higher clay content, is harder, and often lighter in color. It's not suitable for plant growth, but it still plays a crucial role as it supports deep-rooted plants and houses excess minerals.

No-Dig: The Gardeners' Gospel

Contrary to popular belief, mixing the two soil layers isn't ideal. If you till with a 6-inch deep tool, for example, you get a mix of the two layers. Despite initially appearing loose and nice, the freshly tilled top layer can harden into a rock over time.

A well-established garden requires at least 6 inches of topsoil for healthy plant growth. If your garden has struggled, it might be due to mixing topsoil with subsoil, creating poor quality soil. In such cases, consider stopping tilling and building up the soil by adding compost on top.

For those who prefer tilling, incorporate a good amount of compost each time to gradually improve the soil over time.

Fresh Garden Plots: Digging Deeper

When starting a new garden bed, carefully examine the topsoil and subsoil quality. Dig a vertical hole to reveal the layers. Once the digging becomes challenging, you've likely reached the subsoil.

In new subdivisions, topsoil is frequently removed using heavy machinery. If you don't find the subsoil layer and the soil is tough to dig, it's reasonable to assume there's little topsoil to speak of. In such cases, loosen the subsoil with a fork, do not turn, and cover it with one of the recommended no-till options.

When converting a field into a garden, keep in mind its cultivation history. You might find the same situation as a tilled garden, with shallow topsoil where it turns into a mix of top- and subsoil.

Once again, the best way to deal with it is to cover the soil with organic matter to build up the desired topsoil.

In our trial to convert a hayfield into a garden, we used a shallow till, ensuring not to go deeper than the topsoil. We did not bother finding out the soil situation as it wasn't our garden at the time. Now, preparing a pasture on our new land, we'll be investigating the soil situation more thoroughly.

When and How to Double Dig

Double digging separates the topsoil from the subsoil and loosens both independently.

Mixing the topsoil with the subsoil is generally not ideal, but there are situations where doing so might be beneficial. For instance, when there's very shallow topsoil (e.g., 3 inches), removing the topsoil and loosening the subsoil can be a good idea.

Another circumstance where double digging might be necessary is when the subsoil is excessively hard, such as clay-based soil. In such cases, double digging can help break up the subsoil, making it easier for water to drain and for earthworms to inhabit.

After loosening the subsoil, replace the topsoil and cover it with 3 more inches of organic mulch. Here's a helpful video on how to double dig.

Alternatives to Double Digging

Double digging can be labor-intensive, so alternatives are available. If you have a garden with poor soil, little topsoil, or compact subsoil, it may show signs of growing deep-rooted weeds such as dandelions, bitter dock, or goldenrod.

Instead of double digging, let these weeds grow, allowing their roots to penetrate deep into the soil. Once the plants have no way to photosynthesize, the roots will die. Consider also planting deep-rooted plants like forage radish to help loosen the soil.

Broadfork: Your Friend in the Garden

Lastly, let's discuss the broadfork. While a garden fork can work, a broadfork is more suitable for larger gardens. A broadfork only loosens the soil without disturbing the layers, making it a great tool. Simply drive it into the ground, wiggle a bit to loosen the soil, and pull it out. Repeat this every few inches to loosen the soil to the depth of the fork.

In combination with deep-rooted plants, using a broadfork will gradually improve the soil over time. Each year, add a layer of mulch on top to build up the topsoil.

Now you understand the ins and outs of digging, no-digging, and double digging. Share your double-digging experiences in the comments below, and subscribe to our website, follow us on Instagram, Facebook, or Pinterest for the latest updates.

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1. Embrace the no-till method, often favored by gardeners, as it's generally better for soil life, and build at least 6 inches of topsoil for healthy plant growth in a well-established garden.
2. In a new garden bed, carefully examine the topsoil and subsoil quality, dig a vertical hole to reveal the layers, and consider covering the soil with organic matter if mixing topsoil with subsoil could lead to poor quality soil.
3. For those with shallow topsoil or excessively hard subsoil, double digging separates the topsoil from the subsoil and loosens both independently, making it easier for water to drain and for earthworms to inhabit.
4. chopped and drop gardening, or allowing deep-rooted weeds like dandelions, bitter dock, or goldenrod to grow, allows their roots to penetrate deep into the soil, and encourages the growth of deep-rooted plants like forage radish to help loosen the soil.
5. The broadfork, a tool that only loosens the soil without disturbing the layers, is perfect for large gardens, and when used in combination with deep-rooted plants, can gradually improve the soil over time.
6. Build and maintain organic raised beds in your home-and-garden lifestyle to encourage improved soil health, and consider the no-till method for your garden plot in a cold climate for a garden that is more resilient and sustainable.
7. Embrace organic gardening practices, such as incorporating compost and no till methods, for healthier soil, less weed growth, and a more sustainable lifestyle, whether you are planting seeds in a garden bed, a container, or a raised bed.

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