Square-Foot Garden Planner

How square-foot gardening works

Square-foot gardening is a simple idea with a big payoff: divide a raised bed into one-foot squares, and plant each square according to how much room the crop needs. A square of carrots holds sixteen plants; a square of lettuce holds four; a square of bush beans holds nine; and a tomato needs a whole square — or four, if it is a sprawling variety. The grid replaces rows and paths, so a 4×4 foot bed grows as much as a much larger traditional plot, and every square is reachable from the edge of the bed without ever stepping on the soil.

How many plants per square?

The numbers come from spacing, and they follow a simple pattern. If a crop is spaced 3 inches apart, sixteen fit in a square foot (four across by four down). At 4 inches, nine fit. At 6 inches, four. At 12 inches, one. That is the whole system — the calculator applies it automatically from the spacing in our crop database, so you do not need to memorise anything. Crops spaced wider than 12 inches break the pattern in the other direction: a tomato spaced 24–36 inches needs two to four squares, a squash needs four or more, and corn needs a block of at least four squares to pollinate properly. The planner flags those crops so you can see the space they really take before you commit to them.

Planning a bed that works

Start with what you eat, not with what looks good on a chart. A 4×4 bed has sixteen squares: give four to tomatoes, two to lettuce, two to carrots, two to beans, and the rest to herbs and a pepper or two, and you have a summer of salads and sauces from sixteen square feet. Mix tall and short crops so nothing shades its neighbour — put tomatoes and corn on the north side of the bed (in the northern hemisphere) so their shadows fall outside it, and keep low crops on the sunny side. Mix families too: the same family in neighbouring squares shares pests and diseases, while a mix of vegetables, herbs and flowers confuses pests and uses the space better. Marigolds and basil tucked into spare squares are not decoration — they are pest management.

Think about the season, not just the moment. A square of lettuce sown in spring is finished by early summer, and the same square can then hold beans, then autumn spinach — three crops from one square in a year. Plan for that turnover when you lay the bed out: keep a few squares in reserve for succession sowings, and note what went where so you can rotate families next year. And keep the bed reachable: 4 feet wide is the practical maximum if you can reach it from both sides, and 2 feet if you can only reach it from one. A bed you cannot reach the middle of is a bed you will stop weeding.

Soil, water and honest limits

Square-foot beds are almost always raised beds, and raised beds dry out faster than ground-level soil — especially shallow ones in full sun. Water deeply and mulch the surface, and check moisture with a finger rather than a schedule. The soil in a square-foot bed should be loose and rich — the classic mix is a third compost, a third peat or coir, and a third coarse vermiculite — and it needs topping up with compost between crops, because intensive planting takes a lot out of a small volume of soil. The method is not magic: it grows a lot in a small space because it uses space well and asks for regular attention, not because it breaks the rules of how plants grow. A crowded square grows less than a well-spaced one, whatever the chart says — so trust the spacing, thin ruthlessly, and let each plant have the room the calculator gives it.

Related tools: work out exact spacings with the Plant Spacing Calculator, find out how much soil your bed needs with the Soil Volume Calculator, and check what your bed should yield with the Vegetable Yield Estimator. For what to plant this month, see the Garden Planner.