Square Foot Gardening: Plants Per Square Chart, Soil Mix and a 4×4 Layout

Square foot gardening is a tidy, beginner-friendly way to grow a lot of food in a small space. The method was developed and popularized by Mel Bartholomew, whose book Square Foot Gardening first came out in 1981, and extension services now teach the same basic idea as intensive or small-scale gardening. Instead of long rows with paths between them, you plant a grid where every square is within reach. This guide covers how to build and fill a bed, a full plants-per-square chart from Clemson Extension, a sample 4×4 layout that passes our companion checker, and how to keep every square producing all season.

How square foot gardening works

University of Maine Extension describes it as a special type of raised-bed gardening: the bed is divided into 1-foot squares, and each square gets a defined number of transplants or seeds. Because you sow at the final spacing listed on the seed packet rather than sowing thickly and thinning, it uses very little seed. The plant count follows the packet's in-row spacing:

• 1 per square for crops normally spaced about 12 inches apart, such as tomatoes, peppers and cabbage.
• 4 per square for crops spaced about 6 inches apart, such as leaf lettuce and Swiss chard.
• 9 per square for crops spaced about 4 inches apart, such as bush beans, beets and spinach.
• 16 per square for crops spaced about 3 inches apart, such as carrots and radishes.

The payoff is space. Clemson Extension compares it with conventional rows, which it estimates take roughly 100 square feet per person for a season of fresh vegetables, and suggests one 4×4 bed of 1-foot squares (16 square feet) per person for fresh eating instead, plus a second bed per person if you want extra to preserve.

Build the bed

• Size: 4 by 4 feet is standard, giving 16 squares. University of Maine Extension notes you can build 3×3 or 2×2 beds for smaller spaces or children; the rule is that you can reach the middle from any side without stepping in the bed. Several 4×4 beds are easier to manage than one huge one.
• Frame: UMaine suggests four boards about 1 inch thick, 6 inches wide and 4 feet long, screwed together at the corners. UMaine specifies boards that are not pressure treated; bricks or blocks work too.
• Depth: about 6 inches is enough for most crops. Carrots, parsnips and potatoes do better with a deeper bed or a deeper section.
• Bottom: Clemson Extension lines the bottom with cardboard to smother weeds before filling.
• Site: full sun, ideally 6 to 8 hours or more of direct sun, on a level spot near a hose. Leave a path wide enough to kneel on all four sides.

Fill it with a light, rich mix

The classic square foot mix is equal parts by volume of compost, peat moss and coarse vermiculite. University of Maine Extension describes it and notes that Bartholomew recommended blending several kinds of compost, that coir is a more sustainable substitute for peat moss, and that a 4×4 bed about 6 inches deep needs about 8 cubic feet of mix in total, so roughly 2⅔ cubic feet of each ingredient. Mix it on a tarp or in a wheelbarrow and fill the box to the top.

You do not have to use that exact recipe. Clemson Extension says a commercial raised-bed planting mix works too. If a bagged mix uses perlite instead of vermiculite, an Ask Extension answer explains the difference: both add air, but vermiculite holds water longer while perlite lets the bed dry out faster between waterings, so either can work.

Mark the grid

Clemson Extension's method: measure 1, 2 and 3 feet along each side of the frame, set a nail or push pin at each mark and stretch tight string across in both directions. For a permanent grid, UMaine suggests thin wooden lath or old blind slats screwed to the frame. A visible grid is the heart of the method: it keeps spacing honest, shows at a glance which square is free, and makes it easy to plant one square at a time.

Plants per square: the chart

These counts are from Clemson Extension's sample planting guide. Use them as a starting point and adjust for your varieties: a compact patio tomato and a sprawling heirloom take very different amounts of room, and the seed packet's spacing is the best tiebreaker.

Vining winter squash, melons and pumpkins are the hard cases. Clemson lists winter squash at one plant per square only when it is staked or trellised; left to sprawl, one plant easily covers several squares or spills over the edge. Corn needs a block of plants to pollinate, so plant it four per square in a block of at least four squares; see our Three Sisters guide for a small block.

A sample 4×4 summer bed

Here is a 16-square summer bed for tomatoes, cucumbers, peppers, basil, lettuce, carrots and bush beans. Every pair in it is a listed companion or neutral in our companion planting checker; there are no onions or garlic near the beans and no potatoes near the tomatoes.

Companion planting in a grid

In a square foot garden, every plant is a close neighbor, so companion planting is easy to get right and easy to get wrong. A few rules keep a grid happy:

• Check the whole bed, not just neighbors. Squares are only a foot apart, so treat everything in one 4×4 bed as planted together. Run your list through the companion checker before you plant.
• Keep-apart pairs go in different beds. Beans or peas with onions and garlic, and tomatoes with potatoes, are the pairs our sources most often list as poor neighbors; see what not to plant together.
• Tall at the back. Trellised peas, pole beans and cucumbers and caged tomatoes go along the north edge so they do not shade the rest of the grid.
• Flowers in corner squares. A marigold or nasturtium in a corner square brings color and flowers for beneficial insects without taking a whole row; see nasturtium companion plants.

When to plant each square

A grid makes timing simple, because each square is its own little planting. Start cool-season squares (peas, spinach, lettuce, radishes, carrots) a few weeks before your last spring frost, and fill warm-season squares (tomatoes, peppers, basil, beans, cucumbers) after it. Use the planting calendar to get the window for each crop from your frost date.

When a square is harvested, replant it. University of Maine Extension's advice is to mix a trowel of compost into the square each time you make a change, then sow or transplant the next crop, so a spring radish square can become bush beans in early summer and lettuce again in fall. Our succession planting guide has sowing intervals for quick crops that suit a square-by-square rotation.

Water, feeding and upkeep

• Water: a shallow bed of light mix dries faster than garden soil, especially in summer. Water at the base of plants when the top inch is dry; a small watering can or a soaker hose run through the grid works well.
• Feeding: UMaine notes that the compost-rich mix may make extra fertilizer unnecessary. Clemson Extension's advice is to fertilize according to a soil test, so test before adding anything.
• Topping up: the mix settles and breaks down over time. Add compost as you replant squares, and top the bed up when the level drops.
• Rotation: move crop families to different squares or beds each year to reduce soil-borne disease, just as you would in rows.

Common mistakes

• Using heavy garden soil in a shallow bed. Plain soil compacts and drains poorly in a 6-inch box. Use a light mix.
• Overcrowding big crops. One sprawling tomato or zucchini can swallow four squares. Cage, stake or trellis them, or give them more squares.
• Planting everything on day one. The grid works best when squares are planted and replanted through the season.
• Ignoring the keep-apart list. Close spacing means bad neighbors really are next door.

To plan the rest of the garden around your beds, see our vegetable garden planner guide.

Frequently asked questions

How many plants go in a square foot garden square?

It depends on the crop. Clemson Extension's counts include 1 tomato, pepper or cabbage, 2 trellised cucumbers, 4 leaf lettuce, basil or onions, 8 trellised peas or pole beans, 9 bush beans, beets or spinach, and 16 carrots or radishes per square.

What soil do you use for square foot gardening?

The classic mix is equal parts by volume of compost, peat moss (or coir) and coarse vermiculite. A 4×4 bed about 6 inches deep needs about 8 cubic feet. A commercial raised-bed planting mix also works.

How deep does a square foot garden need to be?

About 6 inches is enough for most vegetables. Carrots, parsnips and potatoes do better in a deeper bed or a deeper section.

What should not be planted together in a square foot garden?

The same pairs as in any garden: our sources most often list beans or peas with onions and garlic, lettuce with onions and garlic, and tomatoes with potatoes, corn, fennel or cabbage-family crops as poor neighbors. Put them in different beds.

Can you plant corn or squash in a square foot garden?

Yes, with care. Corn needs a block of plants to pollinate, so plant at least four squares of it. Squash should be staked or trellised at one plant per square, or given several squares.