Plant Spacing Calculator

In short How many plants fit in a bed is a division, but which division depends on how you arrange them, and the difference is bigger than most people expect. A square grid at spacing s gives every plant a cell of s by s. A TRIANGULAR or offset grid shifts every second row sideways by half a spacing, which lets the rows sit closer together while every plant keeps exactly the same distance from every neighbour. How much closer is fixed by geometry: three plants at the same spacing form an equilateral triangle, and the height of an equilateral triangle is its side times the square root of three over two, or 0.8660. So the rows close up by 13.40% and the ground holds 15.47% more plants. That figure does not depend on the spacing, the crop or the units — the spacing cancels out of the ratio entirely, which is why it is the same number for lettuces at 8 inches and for apple trees at 20 feet. HERE IS THE PART THAT ALMOST NO CALCULATOR SAYS. That 15.47% is a DENSITY, and a bed holds a whole number of plants. In a small bed the offset rows lose their last plant while the extra row never appears, and triangular can fit exactly the same number or fewer. A 4 by 8 foot raised bed at 12 inch spacing fits 32 plants square and only 30 triangular. A 10 by 20 foot plot at the same spacing fits 200 square and 215 triangular, a real gain of 7.5% rather than 15.47%. The rule is that offsetting pays once the bed is deep enough for the tighter row pitch to buy a whole extra row. This page shows both counts side by side so you can see which case you are in. The spacings themselves are the one thing here that is not arithmetic. Seed packets, extension services and experienced gardeners disagree by a factor of two on the same crop, because the right answer depends on whether you are growing for size or for total yield, and on how much air a plant needs where you live. Use the figure on your packet and let this page do the counting.