Square foot gardening chart

How square foot gardening works

Square foot gardening is a method popularized by Mel Bartholomew, a retired civil engineer, in his 1981 book Square Foot Gardening and the PBS television series that followed. Instead of long rows with a walking path beside each one, you grow in small beds divided into a grid of one-foot squares and plant every square at a fixed density. The classic bed is 4 × 4 feet: you can reach the middle from either side, so you never step on the soil and it stays loose.

The densities come straight from seed-packet spacing. A carrot needs about 3 inches all around, so a 12-inch square holds four rows of four: 16 carrots. Beets need 4 inches, which gives three rows of three, or 9 per square. Lettuce needs 6 inches, so 4 per square. A tomato, pepper or broccoli plant needs the whole foot. Plants too big for one square, like zucchini and pumpkins, take a block of four or nine.

Bartholomew’s later book, All New Square Foot Gardening (2006), added beds only 6 inches deep filled with “Mel’s Mix”: equal parts compost, peat moss and vermiculite. It is a good recipe, not a requirement. Any loose, rich raised bed soil works, and the raised bed soil calculator tells you how much to buy.

How to read the chart

• The big number is how many plants go in one 1 × 1 ft square. The line under it is the spacing inside that square: 9 per square means three rows of three, 4 inches apart.
• Eight per square is for peas and pole beans: two rows of four along a trellis, 3 inches apart in the row. Cucumbers go two per square, also at a trellis.
• Big plants show their block. Zucchini, yellow squash and cantaloupe take 2 × 2 squares each; winter squash, pumpkins and watermelons take 3 × 3.
• The colored dot is the plant family. Spread each family around the bed and move it to a new spot next year; the companion planting chart shows which neighbors share pests.
• Seeds versus plants: sow two or three seeds in each spot and snip off all but the strongest seedling. That is easier than trying to place single carrot seeds 3 inches apart.

Example: a 4 × 4 ft bed

The north row holds the climbers: two squares of cucumbers on a trellis (four plants) and two caged tomatoes. Below them sit basil, a pepper and marigolds, then lettuce, beets and bush beans, and along the sunny south edge onions, carrots, radishes and parsley. That is 84 plants in 16 square feet.

Radishes are ready in about a month, so that square can be resown three or four times in a season, or handed over to fall lettuce. To plan your own, open the garden planner, add a 4 × 4 ft bed and paint plants into the squares; it fills each square at these densities and keeps a running plant list.

Trellising: why climbers fit

The square-foot numbers for climbing crops assume they grow up, not out. Every plant marked “Needs a trellis” in the chart only fits its count with support:

• Tomatoes: one per square in a sturdy cage or tied to a stake. Indeterminate varieties also need regular pruning of side shoots.
• Cucumbers: two per square on vertical netting. The fruit hangs down and grows straighter.
• Peas and pole beans: eight per square along netting or strings. Pole beans need 6 to 8 feet of height; most peas are happy with 4 to 5.
• Cantaloupe: can climb too, with each melon supported in a sling of cloth or netting as it swells.

Put trellises on the north side of the bed so they don’t shade everything else, and anchor them well. A popular build is a frame of metal electrical conduit with nylon trellis netting. A trellis full of vines and fruit in a summer storm is heavier than it looks.

Pros and cons

What it does well

• More food from a small space. No rows means no paths inside the bed, so most of the ground grows something.
• Less weeding. Densely planted squares shade the soil, and small beds are quick to weed by hand.
• Simple planning. Counting squares turns “how many seedlings do I need?” into arithmetic.
• Easy succession. When a square is harvested, replant just that square instead of waiting for a whole row to finish.
• Small jobs. A 4 × 4 bed is quick to water, cover with row cover or net against birds.

Where it falls short

• Some counts are tight. For broccoli, cabbage and peppers, row spacing guides often say 18 inches. One per square works in rich soil, but in hot climates or with large varieties the plants crowd and stay smaller. Giving them two squares is fine.
• Shallow beds dry out. A 6-inch bed can need water daily in July. Deeper beds, mulch or drip irrigation help.
• Filling beds costs money. Bagged soil and compost add up; buying by the cubic yard is usually cheaper for several beds.
• Not for bulk crops. Sweet corn pollinates by wind and needs a block at least four rows deep, and potatoes or winter squash in quantity are easier in open ground.

Tips for planning your squares

• Mark the grid with string or thin wood strips. Seeing the squares makes it much easier to sow at the right density.
• Keep tall plants at the north edge and low ones at the south, so everything gets sun.
• Fill gaps with quick crops such as radishes, arugula and green onions, harvested before slower neighbors need the room.
• Time each square from your own frost dates: the planting calendar and frost dates by ZIP code tell you when. Each plant’s guide, such as carrots or tomatoes, has the details.

Plants per square foot: the full list

The same chart as a table, for quick reference. Follow a plant’s name for its growing guide.