Plant Spacing Calculator
Work out how many plants you need for a bed or area from the spacing — square grid, triangular (offset) grid or rows.
About this tool
Enter the area of your bed and the spacing between plants from the label or seed packet. Choose a square grid, a triangular (offset) grid or planting in rows, and the calculator shows how many plants you need, plants per m² and per ft², and how the two grid patterns compare. Add a few percent extra if you want spares.
Frequently asked questions
In a square grid, divide 1 by the spacing in metres squared. At 30 cm that is 1 ÷ 0.3² = 11.1 plants per m², at 50 cm it is 1 ÷ 0.5² = 4 per m², and at 20 cm it is 25 per m². Multiply by the area: 10 m² at 30 cm needs 111.1, so 112 plants.
In a triangular (offset or staggered) grid every other row is shifted by half a spacing, so each plant is the same distance from six neighbours. That fits 2 ÷ √3 ≈ 1.155 times as many plants as a square grid: 12.8 per m² at 30 cm instead of 11.1. It gives more even cover, which is why it is often used for ground cover and bedding plants.
Multiply the spacing within the row by the spacing between rows to get the area each plant needs. Plants 30 cm apart in rows 60 cm apart take 0.3 × 0.6 = 0.18 m² each, so you get 1 ÷ 0.18 = 5.6 plants per m², or 56 plants for 10 m².
Use the spacing on the plant label or seed packet. It is based on the size of the plant when it is fully grown and is measured from the centre of one plant to the centre of the next. The calculator works from the area, so along the edges of a bed the real count can differ by a few plants — use the extra field if you want spares for plants that fail.
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