One of many survival garden pitches.

Listen to AM radio for more than a few minutes and you’re bound to hear an ad touting seeds and “one acre survival gardens.” The implication is that hordes of foreclosed zombies will soon empty the shelves of the local Walmart and leave us all bartering for gas with our carefully stored heirloom pole bean seeds.

But it does raise the question of how much space you need to grow all your own food. It’s been on my mind since attending John Jeavons’ three day Grow Biointensive workshop where we spent a fair amount of time, calculator in hand, figuring out how many calories you can squeeze from small spaces.

What gets left out in the “survival garden” sales pitches is that, if you want real self-sufficiency, you’ve also got to maintain the soil fertility that you deplete by harvesting. To do that you need to grow all your own compost. For this, Jeavons suggests what he calls “carbon and calorie crops” things like corn and wheat where you get both something edible and a lot of biomass for your compost pile. In Jeavons’ 4,000 square foot “sustainable one person mini-farm” scheme, 60% of your growing area is devoted to these compost and calorie crops. The remainder is planted in 30% high calorie root crops, such as potatoes, with just 10% of the garden devoted to the usual tomatoes and greens.

The residents of Biosphere 2, using Jeavons’ techniques claimed that enough food could be grown for one person on as little as 3,403 square feet. Jeavons has shown that you could use less space, but you better like eating a lot of potatoes.

In reality, there’s probably too many variables, such as climate, to get an exact figure on how much space you need to grow enough food for one person. And let us not forget the novice survival gardener’s experience (I’m amused at the thought of those one acre survival gardeners busting open that paint can full of seeds for the first time having never gardened before). And if you want livestock, the acreage requirements jump considerably.

But considering that it takes, according to Jeavons, between 15,000 and 30,000 square feet for commercial agriculture to provide the same calories as Jeavons’ 4,000 square foot mini-farm, we’d do well to pull out those calculators on occasion. With just 176 square feet of vegetable beds at the Root Simple compound, our goal is self-reliance, not self-sufficiency. Do you think our post-apocalyptic overlords will feed us in exchange for blogging for them?