If you want to get the most out of each square foot of your garden, one of the best investments is in developing the depth of your garden soil.
Specifically,’ what I’m talking about is a target depth of 24 inches of loosened, aerated, fertile soil. This may seem extreme, especially if you’re read about other methods that recommend only six inches… But it’s my opinion that every inch you increase the depth yields a payoff in the health and productivity of your garden. Vegetable plant roots grow deeper than most of us realize – their complex root systems will use every inch of that two feet.
In future posts, I will address the “HOW” of achieving this goal – through techniques like double-digging and building up raised beds, but for now let’s briefly address the common question, “But why so deep??”
For one, it allows us to grow plants closer to each other, without creating a situation of unhealthy competition between the plants [Close-spaced plantings are better for the soil, produce healthier plants, require less watering, and more space-efficient] – but you can only use close spacing if you have the depth of soil to support it. Picture a pair of plants growing close together in 6″ of good soil, with a hard pan of shale and clay beneath. The roots will grow generally downward, until reaching the hard shale, at which point the roots will abruptly spread outward, as they search for nourishment. The roots of the two plants will intertwine, and will ultimately rob each other of nourishment and water. Neither plant will do well, and in that soil, the only solution would have been to plant further apart in the first place. Now picture the same plant in 24 inches of soil. Pretty obvious, right? The roots will continue growing more-or-less downward, and the two plants will have little if any competitive effect on one another.
The best gardeners are ones who observe and seek to understand the principles, processes & cycles of Creation, and attempt to integrate these principles into their gardens. Here are a couple of the most basic observations of nature that we can bring into the garden 1) In untouched nature, soil is very deep and fertile, because it is built slowly, over time. Widespread soil compaction is fairly rare in nature, so the fertile soil is deeply aerated. 2) Plants in nature grow close to one another, creating a kind of ‘blanket’ or ‘living mulch’ that shades and protects the soil. As we try to nurture these ‘creation-like’ conditions in our gardens, they will thrive.
As I always stress to my gardening students and customers, one of the great virtues that gardening promotes in us is patience. You won’t achieve perfect, deep soil in one or two seasons. But keep the goal of deep, fertile soil at the core of all of your gardening plans and activities.