Square Foot Gardening is a method of intensive planting that was developed by retired civil engineer Mel Bartholomew, and introduced to the rest of the world in his book Square Foot Gardening in 1981. The aim of the method, according to Bartholomew, was, “To replace the traditional wasteful single row gardening method with a better way to garden, one that’s more efficient, more manageable, and less work.”
The book was a huge success, and was followed by a television series that ran on PBS, The Discovery Channel, and The Learning Channel for eight years. Since that time, Bartholomew developed the Square Foot Gardening Certified Instructor Program, and founded the Square Foot Gardening Foundation, which has as its mission the goal of ending world hunger by teaching people how to grow nutritious produce with limited resources.
The Square Foot Gardening method is fairly straightforward.
- You start by building a box that is 4 feet long, 4 feet wide, and 6 inches deep, using untreated wood or any other non-toxic material you can find, like bricks or cinderblocks.
- Place the box on top of some sort of weed-blocking substance, like landscape fabric or a weed mat. Combine what has become known as “Mel’s Mix”: 1/3 Coarse grade Vermiculite, 1/3 Sphagnum Peat Moss or Coconut Coir, and 1/3 Blended Organic Compost. Note: these ingredients are measured by volume, not by weight.
- Fill the box with the mix.
- Place a grid that divides the area of your filled box into 12 square foot boxes. This grid can be made either from something like venetian blinds, or the wood lath that you see in home improvement or garden centers. It doesn’t really matter.
- Whatever grid you use, you’ll need to secure it to the box, because it will stay there for the entire growing season. If building isn’t your thing, Square Foot Gardening is such a popular method that pre-made beds and grids can be purchased online, or even in some of the more savvy garden centers.
After you’ve assembled your bed, filled it, and gridded it, it’s time to plant your seeds and/or plants. How many seeds or plants can go into each 12 square foot box depends on the size of the full-grown plant.
Plants like broccoli, cabbage, tomato, and pepper will take up the entire square foot. Leaf lettuce, Swiss chard, and marigold can be planted four to a square foot. Bush bean, spinach, and beet can be planted nine per square food. Carrot, radish, and scallion can be planted sixteen to a square foot, however, the carrot will need to be one of the shorter varieties, unless you make your box 12 inches deep, or make/acquire a little square foot frame “hat” to put on top of the area where you want your carrots, and fill it with more mix before you plant your carrot seeds.
This makes sense when you remember that carrots are root vegetables, and need nice fluffy soil to snake down into. More of those hats will also allow you to plant potatoes, another root vegetable that needs deep soil. When you harvest a crop from a square foot, add a layer of compost and work it into the soil before you plant another. This is to help replenish the soil for the new planting.
Ideally, you should plant a different crop in each adjoining square foot. Among the many reasons for this are to stagger your harvest, to avoid over-planting any one crop, to encourage companion planting and crop rotation, and to avoid having so many of the same crops close together that their insect predators know just where to go. As a bonus, this approach is aesthetically pleasing, much like a 3D patchwork quilt.
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