The longest foot

Square Foot gardener Mel Bartholomew talks about his method of growing big produce in little spaces

Mel Bartholomew developed square foot gardening.

Mel Bartholomew developed square foot gardening.

Mel Bartholomew is the author of the biggest-selling gardening book ever, Square Foot Gardening, which was published in 1981. He got his gardening start after retiring from his career as a civil engineer. He grew frustrated at the wastefulness of traditional gardening methods and began experimenting with new ways to use resources more efficiently. In 2006, he published All New Square Foot Gardening, which again rocketed to the bestseller lists. Nowadays, the gardening guru is heading up a nonprofit, the Square Foot Foundation, to teach people in poor countries how to grow food with limited recourses. He’s going to teach a seminar in Reno, “Everything You Need to Know about Square-Foot Gardening,” on May 2 at Moana Lane Nursery.

I have been using many of your techniques from the first book for many years now, but I have to admit I haven’t bought the new one yet.

You’re in for a big surprise. We’ve made 10 major improvements to the system to make it even easier, even better, less work.

Let’s talk about those improvements.

Well, in the first one, I said to lay out a 4-foot-by-4-foot area. Of course, pick a good location. And then dig up the first six inches of your soil. Put that aside and to that six inches of your existing soil, we’re going to add two inches each of three different ingredients: peat moss, vermiculite and compost. Mix it all together, and you now have 12 inches of improved soil. And because you have 12 inches, you now have to build a box to hold the extra six. So now the original square-foot system was growing in 12 inches of improved soil. It’s still divided up with a grid. I had the boxes spaced 12 inches apart, and I was using just a plank of 1-by-12 to lay down and walk on. That proved much too narrow, especially when the plants grew. So one of the improvements is to make your boxes at least three feet apart—even four, if you want to have more room to get in.

The major improvement goes back to digging up your existing soil. What happened, Brian, is I went around the country, and everyone’s saying, “Oh, it’s wonderful, it works great, but”—and you know, every time you hear ‘but,’ you wonder, ‘What’s coming, now?’—they said, “It’s a lot of work.” And I’d say, “Hey, you used to have to dig up your whole garden.” I went back to the drawing boards, and I experimented with trying to grow in less depth. What I ended up finding, after growing for a year and experimenting, is plants—all plants, including plants that we thought were deep-rooted plants, like corn, tomatoes—all plants will grow better in six inches of perfect soil than in 12 inches of improved soil. So now we don’t have to improve our existing soil.

Right. OK.

So those same six inches that we used to add to our existing soil, forget about adding. Forget about digging. Just build a box six inches deep on top of your existing soil, take out any weeds or grass, put down a weed cloth, so weeds won’t come up into your good soil, and you fill your box with six inches of perfect soil. It’s the same two inches of peat moss, two inches of vermiculite and two inches of compost. And your plants will do much better than before, and there’s no work.

In layers or do you mix it up?

Yeah, those three ingredients get mixed. And you put a grid on top of it and divide the surface into 16 squares for a 4-by-4. Kids use a 3-by-3 because they can’t reach in.

That’s what I use, too.

You walk around your box, and you reach in. You never walk on your growing soil. If you never walk on it; it never gets packed down. And because it’s a perfect soil, it holds its structure, whereas existing soil packs down even if you don’t walk on it. Now you have a perfect soil. It holds water, and it also breathes air. If it has too much water, it drains out the bottom so the plants can get air. The plants can get air, which is what they have to have.

That’s what the water does, it delivers oxygen to the roots, right?

The roots sort of breathe just like we do. So now you have six inches of perfect soil, and it will last forever. So what I devised is when you harvest, for each square foot, you add just a handful of compost. Just mix it in, and it reenergizes that soil. So now what we’re doing is getting crop rotation and soil improvement, and you don’t even have to know anything about soils. It’s kind of like tools—if you don’t have to know whether soil is clay or silty or sandy—you don’t have to learn any of that anymore. So there’s very little you have to learn to do square-foot gardening. We realized that people who have failed or brand new gardeners are afraid to start, and they’re afraid of failure, so this makes it much easier for them to start—because they don’t have to learn a lot of stuff.

Did we get to 10 improvements?

We got the spacing, don’t dig up your existing soil, the handful of compost each time, crop rotation, then there’s a protection of the soil.

What do you mean by that?

When you make the soil mix, it’s very loose and very friable. And people would write and say, “My cat thinks I made a new litterbox,” or “My dog digs in it because it’s so nice.” So we developed a cage—this is in the new book in pictures, so you can see how to make it—you make a cage that fits right over your existing garden, 4-by-4, it’s made out of chicken wire.

Is that an improvement? That’s the one I use, maybe I invented it before you. It’s just four inches tall with chicken wire over the top to keep the quail out.

[Ours] we make two feet high. The higher you make it, the taller the plants can grow. Because you [don’t] want them to grow through, and then you can’t take it off. So, yeah, if you have quail there, and they come and eat the young seedlings or even the seed, it’s perfect for them. The other thing is, if it’s two feet high in the springtime, you can throw a piece of plastic over it. Now you have yourself a green house, and it has enough height to let the heat out.

That would be good for things like lettuce, too. You could keep them from bolting when the summer comes in …

You can put shade cloth over it. That’ll hold the lettuce, that’ll keep cabbage from bolting, too. … The other major improvement is you don’t use fertilizer now. In the original book, because we were improving existing ground, you had to add fertilizer. We gave you a choice: commercial, chemical or organic. Now, because one-third of this new soil is compost, all-organic, all natural. We found in research and testing all over the world that average amount of organic matter in natural soil is about 3 percent. We’re adding 10 times as much, so that means plants will grow much, much better. And now with the new green movement, no fertilizer just fits in perfectly.

You’ve got a nonprofit now?

We’re a nonprofit foundation, a 501(c)3. We started out to go into schools to teach gardening. Then we got involved, especially after the new book came out, which has now been converted to square-meter gardening because it goes overseas. We have projects in Africa and India and the Philippines, all the Third World countries. Our goal is to stop sending food to poor people, but to teach them to grow their own.

But they’re not going to be importing vermiculite.

You’re way ahead of me. Because it’s expensive, and they don’t have it in Third World countries, and they couldn’t afford it even if it was there, our soil mix is pure compost. We experimented in all parts of the world using just compost, and it works fine. Not quite as good as if you could add that peat moss or vermiculite. It packs down a little more, it’s harder to hold water, but it works much better than existing ground. So we use the same principles: Build a box out of any materials—mud or bricks or stones—and have six inches of compost. Put a grid down, you can make it out of bamboo, it’s free all over the world. And a square meter turns out to be almost exactly the same as a square yard, it’s off by an inch or two. So that’s what we take to Third World countries.

Are you going to discuss any benefits of square foot gardening to xeriscaping?

Sure. First of all, square-foot gardening, compared to a single-row garden, takes only 20 percent of the space. That means 80 percent of a single-row garden was wasted. And it takes only 10 percent of the water, yet you grow 100 percent of the harvest. And it takes only 5 percent of the seeds. And it takes only 2 percent of the work. And the best part of it is, there are no weeds, because you started with weedless soil—no seeds. So with no weeds taking up a lot of energy and a lot of water, you use very little water for this since you’ve reduced the space. We teach hand watering because your garden is so small, you really don’t have to use a lot of water. You don’t need a sprinkler or to water from the hose. You water from a bucket of sun-warmed water.

Oh, is there a benefit to having it warmed?

Even with a cool weather plant, if it’s warm, they grow faster. It may grow too fast, perhaps, but all plants grow faster and better in warm weather. So why sprinkle them with cold hose water?

Darn. Because it’s easy.

What a terrible waste of water. Here’s a gardening system that uses very little water. So your plants have perfect spacing, they’re grown in perfect soil that has perfect water. And no competition from weeds. How could this garden not be perfect?