What is Square Foot Gardening?

Square Foot Gardening divides the growing area of a raised garden bed into a grid in which crops are planted according to their mature size. This orderly approach to intensive planting was popularized by author Mel Bartholemew, a former engineer, in his 1981 book Square Foot Gardening. A Square Foot Gardening chart is included below.

Bartholemew introduced order and engineering process into gardening. His system, which he dubbed square foot gardening, incorporates a series of 4’x4′ raised garden beds, each marked with a grid of 16 1’x1′ squares. Each square is planted with 1, 2, 4, 9, or 16 individual crops, depending on their mature size. For example, one grid might hold one broccoli plant, 2 cucumbers, 4 bulb onions, 9 spinach plants, or 16 carrots. Tall plants are trellised on the north side of the garden bed to avoid shading smaller plants. Once a grid or “square foot” is harvested, another crop is planted to take its place, creating season-long production.

Square Foot Gardening incorporates many of the values of crop rotation and companion planting. Once a plant reaches maturity, it’s harvested and that grid is planted with a different vegetable or herb (crop rotation). Different plants grown in high density create a polyculture, which is thought to have positive impacts on pest and disease resistance (companion planting). It also creates living mulches and suppresses weeds (densely planted crops shade out weed seeds).

Season extension with square foot gardening

Square Foot Gardening makes season extension simpler, as it’s much easier to cover a 4×4 bed with a canopy or make a cold frame than it is to cover a large garden bed. It’s also much easier to protect from animals like rabbits and squirrels, as making a cage or fence for the square-foot bed is a much easier task.

How to build a square foot garden

Many gardeners – millions in fact, swear by this method. Square foot gardening offers a simple vegetable garden layout that makes it easy to calculate exactly how many plants can grow in your garden. It’s also convenient for gardeners with limited growing space as the style of planting allows for more plants per square foot than traditional growing methods. Bartholemew recommended 4-foot square beds, but his planting grid can be applied to any existing garden bed. The good news is, it’s incredibly simple.

If you don’t yet have a vegetable garden, read about how to build a raised garden bed. Bartholemew recommends 4’x4′ beds because they grid evenly, but honestly, you can make the garden bed any size. When deciding on the width of your raised garden beds, the rule of thumb is that you should be able to reach halfway across the bed comfortably to make maintenance and harvesting easy. The length is your choice.

Use of Landscape Fabric

In his books, Bartholemew recommended the use of landscape fabric on the bottom of the garden bed to prevent weeds. That was back in 1981. This is no longer a recommended practice as it inhibits drainage, insect movement, bioactivity, and gas exchange in the soil. Plus, weeds are not a significant problem in square foot gardening, as the dense planting shades out weed seeds.

Bartholemew also experimented with various planting mixes for his square foot gardens and eventually arrived at “Mel’s Mix”: 1/3 peat moss or coconut coir, 1/3 vermiculite, and 1/3 blended compost. Bartholemew claimed that this mix yielded superior results in only a 6” depth, kept the soil friable, reduced weeds to almost zero, and eliminated the need for artificial fertilizer. The mix is added each time a new square is planted and provides enough nutrients to support the plants. I wouldn’t recommend a depth of only 6″ however, as it’s very shallow for the likes of tomatoes, onions, and potatoes and may pose drainage problems in some soils. I would recommend at least 9″.

Steps in building a square foot garden:

1. Measure your garden area Measure the garden bed and divide it into 12″x12″ sections. Bartholemew recommends that you make a wooden grid and permanently attach it to the top of the bed so your grid is always present.
2. Fill with soil mix Fill your garden beds with high-quality soil, if you haven’t done so already. Bartholemew recommends his “Mel’s Mix” of 1/3 blended compost, 1/3 peat moss, and 1/3 coarse vermiculite. This mix should guarantee adequate drainage and sufficient fertilization all season.
3. Trellis Tall plants that need trellising should always be on the North side of the bed so they don’t shade out smaller plants. Attach a trellis to the end of the bed that is closest to North.
4. Plant Plant your grids according to the mature size of each plant. Grow 1, 4, 9, or 16 equally spaced plants per square foot.

Square Foot Gardening Plant Chart and Spacing Guide

The square foot gardening chart shows the number of plants of that variety recommended for each 12″x12″ square. Source: Square Foot Gardening Foundation.