Plant Spacing Calculator
Find out how many plants will fit in your bed at a given spacing.
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plants will fit
| Bed area | – |
|---|---|
| Rows × plants per row | – |
| Plants per m² | – |
Plant spacing calculator
This garden calculator works out how many plants, seedlings, or bulbs you can fit into a bed at a chosen spacing. Enter the size of your bed and the recommended spacing between plants, choose a square or triangular layout, and it gives the total number of plants, the rows, and the planting density per square metre.
Square vs triangular spacing
A square grid is the simplest layout — plants line up in straight rows and columns. A triangular (offset) layout staggers each row so plants nestle into the gaps, fitting roughly 15% more plants into the same space while keeping the same minimum distance between them. It is a great way to make the most of a small bed.
Getting spacing right
Always follow the spacing on the seed packet or plant label — overcrowding reduces airflow and yields. Once you know how many plants you need, prepare the bed with the right amount of soil using our garden soil calculator, and feed them with help from the fertiliser calculator.
Frequently asked questions
How many plants per square metre at 30 cm spacing?
About 11 plants per m² in a square grid, or around 13 with triangular spacing.
The plant spacing formulas
For a square grid, each plant occupies a square with sides equal to the spacing, so the number of plants is area ÷ spacing². A triangular (offset) layout packs plants more tightly: each plant uses spacing² × 0.866, so the formula becomes area ÷ (spacing² × 0.866). That fits about 15% more plants into the same bed while keeping the same distance between neighbours.
Worked example
A bed 3 m long and 1.2 m wide has an area of 3.6 m². At 30 cm spacing, a square grid needs 3.6 ÷ (0.3 × 0.3) = 40 plants. A triangular layout needs 3.6 ÷ (0.09 × 0.866) = 46 plants. Ground-cover plants and hedging usually suit a triangular layout because it closes gaps faster. Vegetables in rows suit a square grid because it makes hoeing and picking easier.
Typical spacing for common plants
| Plant | Spacing (cm) | Spacing (inches) |
|---|---|---|
| Carrots (after thinning) | 5–7.5 | 2–3 |
| Onion sets | 10 | 4 |
| Lettuce | 25–30 | 10–12 |
| Potatoes (rows 60–75 cm apart) | 30–40 | 12–15 |
| Strawberries | 30–45 | 12–18 |
| Cabbage, broccoli and other brassicas | 45–60 | 18–24 |
| Cordon tomatoes | 45–60 | 18–24 |
| Hardy perennials and ground cover | 30–45 | 12–18 |
These figures are starting points; the seed packet or plant label is the best guide for a particular variety. Compact or patio varieties can go closer, while vigorous varieties need more room.
Square-foot gardening
Square-foot gardening divides a raised bed into 30 cm (1 ft) squares and plants a fixed number of each crop in every square. Common numbers are one tomato or cabbage, four lettuces, nine beetroot or spinach, and sixteen carrots or radishes per square. A 1.2 × 1.2 m bed has sixteen squares, so it can grow sixty-four lettuces or a mix of crops.
Why spacing matters
Space plants for their mature spread, not their size on the day you plant them. Crowded plants compete for water and nutrients, give smaller harvests, and suffer more from fungal diseases because air cannot move between the leaves. Leave room for paths, too — you should be able to reach the centre of a bed without standing on the soil. Once you know the bed size, the garden soil calculator shows how much soil you need to fill it.