What this tool does and when to use it
This calculator counts plants the way you lay them out: it starts half a spacing in from every edge, fits as many plants as the row length allows, then counts the rows across the bed. It handles square grids for vegetables and raised beds, staggered rows for flowers and groundcovers, round beds, and feet or meters.
How many plants fit in a 4x8 raised bed?
These counts come straight from the calculator for a 4 by 8 foot bed, with the first plants half a spacing in from the edge.
| Spacing | Square grid | Staggered rows | Good for |
|---|---|---|---|
| 4 in (10 cm) | 288 | 306 | Carrots, radishes, onion sets |
| 6 in (15 cm) | 128 | 140 | Garlic, leeks, beets |
| 9 in (23 cm) | 50 | 60 | Bush beans, small herbs |
| 12 in (30 cm) | 32 | 30 | Lettuce, potatoes, peppers |
| 18 in (45 cm) | 10 | 9 | Broccoli, cabbage, kale, strawberries |
| 24 in (60 cm) | 8 | 7 | Tomatoes, eggplant |
A 4 by 4 bed holds half the close spaced counts and 4 plants at 18 or 24 inches. A 10 by 4 bed holds 40 plants at 12 inches, 12 at 18 inches and 10 at 24 inches in a square grid.
Vegetable spacing chart
Spacing is center to center within the row. Rows are the gap between rows if you plant in long rows; in a raised bed or block planting, use the plant spacing both ways.
| Crop | Plant spacing | Between rows |
|---|---|---|
| Garlic | About 6 in (15 cm) | 12 to 18 in |
| Onions | 2 to 5 in (5 to 13 cm) | 12 to 24 in |
| Carrots | 1 to 3 in (3 to 8 cm) | 12 to 16 in |
| Lettuce | 10 to 16 in (25 to 40 cm) | 16 to 18 in |
| Potatoes | 7 to 12 in (18 to 30 cm) | About 30 in |
| Broccoli, kale | 12 to 24 in (30 to 60 cm) | 18 to 36 in |
| Cabbage | 18 to 24 in (45 to 60 cm) | 2 to 4 ft |
| Peppers | 12 to 18 in (30 to 45 cm) | 24 to 30 in |
| Tomatoes | 18 to 30 in (45 to 75 cm) | 3 to 4 ft |
| Strawberries, June bearing | 18 to 24 in (45 to 60 cm) | 3 to 4 ft |
| Summer squash, zucchini | 3 to 4 ft (90 to 120 cm) | 6 to 10 ft |
Figures are the usual ranges from US university extension guides and seed company planting charts. Closer spacing gives more but smaller garlic heads and potatoes; wider spacing gives fewer, bigger ones. Always check the seed packet for your variety, because compact and bush types can go closer.
How to work out how many plants you need
Plant labels give a spacing, the distance from the center of one plant to the center of the next when both are fully grown. This is how the calculator turns that into a count.
- Start half a spacing in. Plant the first row half the spacing in from the edge of the bed or path, so plants don't spill over as they grow. At 18 inches, that is 9 inches in.
- Count plants per row. Divide the bed length by the spacing and round down. A 10 foot bed is 120 inches, and 120 divided by 18 is 6 plants.
- Count the rows. Divide the bed width by the spacing and round down. A 4 foot bed is 48 inches, so 2 rows at 18 inches.
- Multiply. 6 plants times 2 rows is 12 plants.
Many calculators simply divide the area by the space each plant needs, which gives 18 for the same bed. That only works if the outer plants sit right on the edge, so in a raised bed it overcounts. We show that figure as a note when it differs.
Square grid or staggered rows?
A square grid is easy to lay out and suits vegetables in rows and raised beds. A staggered, or triangular, layout places each plant in a zigzag so every plant is the same distance from its neighbors. Rows sit closer together, so in a large bed it fits up to about 15 percent more plants and fills in faster, which is why designers use it for groundcovers and flower borders. In a small bed the shifted rows lose a plant each, so a square grid can hold as many or more; the calculator shows both, so compare them.
Crowded plants compete for water and light and are more prone to disease, while plants spaced too far apart leave bare soil for weeds. Following the label and covering gaps with mulch in the first season gives the best of both. For planting ideas, see our small garden and backyard ideas and summer patio ideas, fill the bed with the raised bed soil calculator and work out the mulch with the mulch calculator.
