Plant Spacing Calculator
How many plants fit a bed at the spacing on the label, in rows or staggered.
Good to know. Staggered rows fit about 15% more plants than a square grid at the same spacing. Bees don’t mind either.
How it works
In plain words
Each plant needs a circle the size of the spacing. In a square grid, divide the length and the width by the spacing and multiply. In staggered rows the rows are only 0.866 of a spacing apart, and every other row is shifted half a spacing, so more rows fit.
The formula
grid: ⌊length ÷ s⌋ × ⌊width ÷ s⌋ staggered: rows = ⌊(width − s) ÷ (0.866 s)⌋ + 1, alternating full and shifted rows
Worked example
A 3 × 2 m bed with plants 30 cm apart takes 10 plants per row. Staggered, 7 rows fit (4 of 10 and 3 of 9), 67 plants, against 60 in a square grid.
Sources
No outside data or rates: this is plain arithmetic.
4 automated tests check its answers on every change.
About the plant spacing calculator
The spacing on a plant label is the distance from the centre of one plant to the next, chosen so they just touch when grown. This calculator works out how many fit a rectangular bed at that spacing, keeping half a spacing from every edge so the outer plants don’t spill over the path.
There are two ways to lay them out. In a square grid every plant sits in line with its neighbours: simple, and good for vegetables in rows. In staggered rows each row is shifted by half a spacing, so the plants form triangles. The rows can then sit closer together, at about 0.87 of the spacing, which fits roughly 15% more plants and covers the ground evenly: the usual choice for ground cover, bedding and hedges in a double row.
For irregular beds, use the area calculator and divide the area by the space each plant takes: the spacing squared for a grid, or 0.87 times the spacing squared staggered.
Wider spacing saves money and gives each plant room; closer spacing fills in sooner. For mulch or soil for the bed, use the mulch, soil and gravel calculator.
Questions people ask
How many plants do I need per square metre?
At 30 cm spacing, about 11 in a grid (1 ÷ 0.3²) or about 13 staggered. At 50 cm, 4 or about 5.
What is triangular spacing?
Rows shifted by half a spacing so each plant sits between two in the next row. It fits about 15% more plants than a grid.
Should I measure from the edge of the bed?
Leave half a spacing from each edge, as this calculator does, so plants don’t grow over the edge.