Plant spacing calculator: know how many plants to buy
Start with one clear planting bed. Enter its measurements and the spacing on your chosen plant’s label to see a simple grid, then take the notes to your nursery or into a garden makeover.
Size your planting bed
Use the centre-to-centre spacing for your chosen plant. In metres, 50 cm is 0.5; in feet, 18 inches is 1.5.
Add a few site notes
24 planting positions
4 rows × 6 plants · 6 m²
Each dot is a plant centre. This grid leaves at least half the selected spacing at each edge. It does not identify plants or infer measurements from a photo.
Choose plants for your climate, sunlight and soil before buying. The count uses your spacing, not a recommendation for a particular species.
Worked example: a 3 m × 2 m bed
At 50 cm spacing, a regular grid fits 6 plants along the length and 4 across the width: 24 plants. Leave half the spacing at the outer edges. At 60 cm spacing, the same bed fits 5 × 3 = 15 plants. Use the mature spread on the plant label, and measure again after excluding paths and existing shrubs.
Measure the space that is actually available
Leave paths, existing trees and features outside the rectangle. For an L-shaped bed, calculate two separate areas. This tool uses a regular grid with one spacing value; it does not optimise a mixed planting scheme.
Give your planting time to grow
Use the eventual spread of the variety as a starting point, rather than the size of the pot. A nursery can confirm the right distance for your planting goal. The RHS perennial planting guide explains how spread affects spacing.