GardenCalcs.uk
Plant Spacing Calculator — How Many Plants Do I Need
Calculate how many plants you need for a given area and spacing.
Longer side of the bed — rows run along this length
Shorter side of the bed — rows are stacked across this width
Centre-to-centre gap between plants — use the mature spread on the label or RHS guidance
Grid = square rows and columns; Staggered = offset rows that fit ~15% more plants
Row spacing multiplier for staggered pattern (default 0.866 = equilateral triangle)
Distance from bed edge to first plant (default 0 = plant from edge)
How We Calculate This
Grid pattern: Rows = Floor(Width ÷ Spacing) + 1. Plants per row = Floor(Length ÷ Spacing) + 1. Total = Rows × Plants per row.
Staggered pattern: Row spacing = Spacing × 0.866 (sin 60°, the equilateral-triangle offset). Alternate rows have one fewer plant. At scale this packs about 15% more plants per area; on a small bed the actual count gain is smaller because of edge rounding (the whole-plant counts at each end).
Frequently Asked Questions
Spacing is measured from the centre of one plant to the centre of the next. A 30 cm spacing means each plant centre is 30 cm from its neighbours.
Every other row is offset by half the spacing. This gives more even coverage and fits about 15% more plants in the same area than a grid pattern.
Check the plant label or RHS guidance. Spacing depends on the mature spread of the plant. Closer spacing gives quicker coverage but plants may become crowded.
Usually plant the first row half-spacing from the edge. This calculator assumes you plant from edge to edge of the given area.
In containers, plants are often placed slightly closer together than in open ground because you control watering and feeding. Reduce spacing by about 20% for container displays.
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Last updated: February 2026
All calculations are estimates based on standard gardening guidelines. Results may vary with soil conditions, climate, and plant varieties.