What does centre-to-centre spacing mean?

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.

What is staggered (triangular) planting?

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.

How do I know the right spacing?

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.

Should I include edge spacing?

Usually plant the first row half-spacing from the edge. This calculator assumes you plant from edge to edge of the given area.

Does spacing change for container planting?

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.

GardenCalcs.uk

Plant Spacing Calculator — How Many Plants Do I Need

Calculate how many plants you need for a given area and spacing.

Bed Length

Longer side of the bed — rows run along this length

Bed Width

Shorter side of the bed — rows are stacked across this width

Plant Spacing

Centre-to-centre gap between plants — use the mature spread on the label or RHS guidance

Planting PatternGrid = square rows and columns; Staggered = offset rows that fit ~15% more plants

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

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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.