# How many plants do I need?

Counts the plants that fill a bed at a given spacing, on a square grid or a staggered triangular grid, with an extra share for edges and losses.

- Page: https://www.acalculator.org/construction/plant-spacing-calculator
- JSON spec: https://www.acalculator.org/construction/plant-spacing-calculator.json
- Version: 2de1c014f256

## Default answer

Example with the default inputs (Bed known by Length and width, Bed length 10 ft, Bed width 10 ft, Plant spacing 12 in, Pattern Square grid, Extra plants 5%): Buy 105 plants (100 to fill the bed, plus extra).

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| by | Bed known by | Whether you know the bed’s length and width, or only its area. |
| l | Bed length | The length of the bed. |
| w | Bed width | The width of the bed. |
| a | Bed area | The area of the bed, for a bed of any shape. |
| s | Plant spacing | The distance between plants, centre to centre, from the plant tag. |
| grid | Pattern | A square grid, or a triangular grid with every other row shifted by half a space. |
| extra | Extra plants | Plants to add for curved edges, corners and losses, in percent. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| plants | Plants to buy | The plants that fill the bed with the extra share, rounded up. |
| fill | Plants without extra | Bed area ÷ the area each plant takes, rounded up. |
| perPlant | Area per plant (ft²) | The area each plant takes: spacing² (square) or spacing² × 0.866 (triangular). |
| perPlantM2 | Area per plant (m²) | The same area in square metres. |
| rows | Row spacing (in) | The distance between rows: the spacing, or 0.866 × the spacing for a triangular grid. |

## Method

Plants = ⌈bed area ÷ area per plant × (1 + extra)⌉, with area per plant = spacing² (square grid) or spacing² × √3 ÷ 2 ≈ 0.866 × spacing² (triangular grid).

## Assumptions

- The count fills the area at the spacing; it does not place plants along the edges. Narrow or oddly shaped beds may take a few more or fewer.
- The 5% default extra follows the nurseries’ advice of 5 to 10% for edges, corners and losses.

## Worked examples

1. by = sides, l = 3.048, w = 3.048, s = 0.3048, grid = square, extra = 0% gives plants = 100, fill = 100, perPlant = 1, rows = 12. Source: University of Missouri Extension, G6835 Ground Covers (Table 1: 100 plants cover 100 ft² at 12 in and 225 ft² at 18 in), https://extension.missouri.edu/publications/g6835; Bloomin Designs Nursery, Plant Calculator (square: area ÷ (spacing × spacing); triangular rows 0.866 × spacing apart; order 5–10% extra), https://www.bloomindesigns.com/plant-calculator/.
2. by = area, a = 20.903184, s = 0.4572, grid = square, extra = 5% gives fill = 100, plants = 105, perPlant = 2.25. Source: University of Missouri Extension, G6835 Ground Covers (Table 1: 100 plants cover 100 ft² at 12 in and 225 ft² at 18 in), https://extension.missouri.edu/publications/g6835; Plant Addicts, Free Plant Spacing Calculator (triangular row spacing = 0.866 × spacing; add 5% extra), https://plantaddicts.com/free-plant-spacing-calculator/ (5% extra).
3. by = area, a = 9.290304, s = 0.3048, grid = triangle, extra = 0% gives fill = 116, perPlant = 0.866025, rows = 10.392305. Source: Bloomin Designs Nursery, Plant Calculator (square: area ÷ (spacing × spacing); triangular rows 0.866 × spacing apart; order 5–10% extra), https://www.bloomindesigns.com/plant-calculator/ (rows 0.866 × spacing apart; about 15% more plants).
4. by = sides, l = 3, w = 1.2, s = 0.3, grid = square, extra = 10% gives fill = 40, plants = 44, perPlantM2 = 0.09. Source: Bloomin Designs Nursery, Plant Calculator (square: area ÷ (spacing × spacing); triangular rows 0.866 × spacing apart; order 5–10% extra), https://www.bloomindesigns.com/plant-calculator/.

## FAQ

### How many plants do I need for my bed?

Divide the bed area by the area each plant takes. At 12 in spacing on a square grid each plant takes 1 ft², so a 10 × 10 ft bed takes 100 plants, or 105 with 5% extra.

### What is triangular spacing?

Every other row is shifted by half a space, so each plant sits at the corner of equal triangles. The rows are 0.866 × the spacing apart, which fits about 15% more plants: 116 instead of 100 in 100 ft² at 12 in.

### Square or triangular, which is better?

A staggered (triangular) pattern covers the ground faster and looks more natural, so it is the usual choice for ground covers and hedges. A square grid is easier to lay out in rows.

### How much extra should I buy?

Nurseries suggest 5 to 10% extra for curved edges, corners and plants that fail. The page adds 5% unless you change it.

### What spacing should I use?

Use the spacing on the plant tag, which is about the plant’s width when grown. Missouri Extension’s table shows how fast it adds up: 100 plants cover 25 ft² at 6 in, 100 ft² at 12 in and 225 ft² at 18 in.

### My bed is not a rectangle. What do I do?

Measure or estimate its area and choose Area. For a round bed, area = 3.1416 × radius²; for an L-shaped bed, split it into rectangles and add their areas.

## Sources

- Bloomin Designs Nursery, Plant Calculator: square spacing divides the area by spacing × spacing; triangular rows are 0.866 (sine of 60°) × the spacing apart and need about 15% more plants; order 5–10% extra. https://www.bloomindesigns.com/plant-calculator/ (retrieved 2026-10-02)
- Plant Addicts, Free Plant Spacing Calculator: triangular row spacing = 0.866 × spacing; option to add 5% extra. https://plantaddicts.com/free-plant-spacing-calculator/ (retrieved 2026-10-02)
- University of Missouri Extension, G6835 Ground Covers, Table 1: area covered by 100 plants at different planting distances (12 in: 100 ft², 18 in: 225 ft²); staggered rows give the quickest cover. https://extension.missouri.edu/publications/g6835 (retrieved 2026-10-02)