Everything You Need for Square Foot Gardening
Six steps to more food than you thought possible in a small space
Carol J. Alexander; Image provided by the Square Foot Gardening Foundation
Square foot gardening is a great way to grow a bounty of produce in a limited amount of space. It’s by no means a new method, but its straightforward, efficiency-maximizing approach to gardening has made it a popular choice among rookie planters and pros alike.
Where Did Square Foot Gardening Come From?
About 40 years ago, Mel Bartholomew witnessed people in his neighborhood struggling to keep a backyard garden. They’d start with enthusiasm, often plowing up a large part of ground and planting enough to feed an army. Over time though, as watering became a chore, weeds grew, and insects came marching in, enthusiasm waned and people’s grand ideas of growing their own food fizzled out.
A retired civil engineer and efficiency expert, Mel knew there had to be a better way. A year later, he introduced square foot gardening, a simple alternative to his neighbors’ inefficient and labor-intensive row gardens.
“Square foot gardening is a simple, yet very productive, method that eliminates weeding, hard work, heavy watering, and all the other negative things associated with row gardening,” says Mel’s son Steve Bartholomew, director of the Square Foot Gardening Foundation (SFGF).
With the square foot gardening method, you plant your seeds or seedlings in 4-foot-by-4-foot boxes in a special soil mixture called Mel’s Mix, which is easy enough to make in your own backyard.
The Advantages of Square Foot Gardening
According to Steve, square foot gardening is one of the most successful gardening methods out there. You can grow more food in less space, using fewer seeds. You water less, and because weeds and pests are scarce, you work less.
And the disadvantages? “None that we can think of,” Steve says.
10 Basic Principles of Square Foot Gardening
The SFGF teaches 10 basic principles for gardeners to follow.
- Plant densely. A small space full of plants leaves little room for weeds.
- Grow up. Use trellises to grow vining plants like tomatoes and cucumbers. Getting plants off the ground saves space and prevents some disease and pests.
- Use Mel’s Mix. A combination of equal parts compost, vermiculite, and peat moss is the perfect food for most plants, according to the SFGF. If you don’t have compost from your own kitchen scraps, Steve recommends buying it. "Use a mixture of several kinds, like manure, worm castings, and mushroom,” he says.
- Garden close to home. Plant your garden close enough to enjoy and easily maintain it. “The square foot gardening method is perfect not just for the backyard, but for the rooftop, patio, or parking lot,” Steve says.
- Grow shallow. Most garden plants can grow in 6 inches of soil. In southern zones, Steve recommends 8 inches.
- Don’t fertilize. Mel’s Mix has all the nutrition your garden needs. When you replant a square, just add another shovelful of compost.
- Keep aisles between boxes narrow. Leave just enough space to get around but not more than you’re willing to weed or mow.
- Be stingy with seeds. In a square foot garden, you don’t plant a bunch and then thin later. You only plant the seeds you need.
- Plant in squares. Divide the 4-foot-by-4-foot box into 16 one-foot squares. In those smaller squares, plant one to 16 seeds, depending on the size of the plants. Mixing different plants in the same box prevents many pests and diseases.
- Rotate crops. As plants mature and you reap the harvest, replant in that square. This type of crop rotation provides the greatest yield possible.
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6 Steps to Building a Square Foot Garden
1. Make a Plan
Draw a diagram of your dream garden. Remember: It doesn’t need to be as large as a typical row garden. “The rule of thumb is one 4-foot-by-4-foot bed per person to produce enough to feed a salad a day throughout the growing season,” Steve says.
In your diagram, divide your four-by-four boxes into 16 squares. Using the recommendations in step 5 for planting below, label what you want to plant and where. Place the tallest vegetables on trellises on the north side of the bed to avoid shading the other plants. Also, plant items that need the most attention along the edges of the box.
With your garden mapped out, choose a sunny location in your yard to place the boxes and decide the configuration you will use to lay them out. Raised boxes can be any size as long as one side is not wider than 4 feet so you can reach in to tend your garden from all sides and never walk on your growing soil. Leave just enough room that you’ll be able to walk all the way around each box comfortably once the plants mature.
2. Build the Boxes
Using 1-by-6 or 1-by-8 untreated lumber, build your 4-foot-by-4-foot boxes. Brick or concrete blocks work well, too. If you want to paint the boxes, only paint the outsides.
Set the boxes in the yard, right on the grass is fine. Lay landscape cloth, weed mat, or cardboard on the ground within each box to prevent weeds from growing up.
3. Make Mel’s Mix
“Your growing soil is the most important part of a successful garden,” Steve says.
In a wheelbarrow or large tarp on the ground, mix equal parts coarse vermiculite, peat moss, and compost and fill the boxes. To find out how much you’ll need, use the handy soil calculator on the SFGF's website.
4. Add the Grids
Grids are the secret sauce to square foot gardening; they help with visualization and prevent you from overplanting, thereby maximizing your harvest. Use thin strips of lumber, old mini-blind slats, or string to divide your boxes into 16 1-foot-by-1-foot squares.
5. Plant Your Crops
When it comes to choosing how many plants you’ll grow in each of your 16 squares, plant either one, four, nine, or 16 seeds or seedlings. Here are some guidelines:
- Extra-large crops, such as broccoli, tomatoes, and peppers: one per square (16 per bed)
- Large crops, such as lettuce, swiss chard, and marigolds: four per square (64 per bed)
- Medium-sized plants, such as beets, kale, and bush beans: nine per square (144 per bed)
- Small plants, such as radishes, onions, and carrots: 16 per square (256 per bed)
In addition, as mentioned above, grow vining plants on trellises on the north side of the bed. You can even do this with pumpkins.
Also, it’s a good idea to devote one box to perennial plants like asparagus or strawberries.
6. Maintain Your Garden
If you’ve been row gardening, you’ll be amazed at how little work a square foot garden requires. Water as needed, by hand at the base of the plants, to prevent disease. Once you harvest a square foot of a fast-growing plant, like lettuce, replace it with a new crop. This staggered planting gives you a higher yield and a longer growing season.
Remove any unwanted pests by picking them off the plant with a gloved hand and depositing in soapy water. Also pick any blighted plants and dispose of properly. Look for weeds too, though you probably won’t find many.