Plant Spacing Calculator
Enter the bed size and the spacing, or pick a plant from the presets, and choose square, triangular or row layout. You get the number of plants, the alternatives side by side, and the cost.
Plants needed
80
80 sq ft at 12" square
Square grid
80
1.00 per sq ft
Triangular
93
offset rows, tighter canopy
Cost
$320
at $4 each
Square: area ÷ spacing². Triangular: area ÷ (spacing² × 0.866). Rows: area ÷ (in-row spacing × row spacing). Edge plants sit half a spacing in from the border; for a border of width W and spacing S, a row holds about W ÷ S plants.
Plants per bed, square spacing
| Bed (ft) | sq ft | 6" | 8" | 12" | 18" | 24" | 36" |
|---|---|---|---|---|---|---|---|
| 4 × 4 | 16 | 64 | 36 | 16 | 8 | 4 | 2 |
| 4 × 8 | 32 | 128 | 72 | 32 | 15 | 8 | 4 |
| 4 × 12 | 48 | 192 | 108 | 48 | 22 | 12 | 6 |
| 3 × 20 | 60 | 240 | 135 | 60 | 27 | 15 | 7 |
| 5 × 30 | 150 | 600 | 338 | 150 | 67 | 38 | 17 |
| 10 × 10 | 100 | 400 | 225 | 100 | 45 | 25 | 12 |
Multiply by 1.15 for triangular spacing.
Common spacings
| Plant | Spacing | Per sq ft | Per 4 × 8 bed | Per 100 sq ft (triangular) |
|---|---|---|---|---|
| Lettuce | 8" | 2.25 | 72 | 260 |
| Bush beans | 6" | 4.00 | 128 | 462 |
| Carrots | 3" | 16.00 | 512 | 1848 |
| Onions | 4" | 9.00 | 288 | 1040 |
| Peppers | 18" | 0.44 | 15 | 52 |
| Tomatoes | 24" | 0.25 | 8 | 29 |
| Squash / zucchini | 36" | 0.11 | 4 | 13 |
| Strawberries | 12" | 1.00 | 32 | 116 |
| Groundcover (creeping thyme) | 10" | 1.44 | 47 | 167 |
| Groundcover (pachysandra) | 8" | 2.25 | 72 | 260 |
| Boxwood hedge | 24" | 0.25 | 8 | 29 |
| Arborvitae screen | 36" | 0.11 | 4 | 13 |
| Daylilies | 18" | 0.44 | 15 | 52 |
| Hostas (medium) | 24" | 0.25 | 8 | 29 |
Edges, rows and reality
- Edge allowance. The formula assumes plants right to the border. Set the first row half a spacing in and the count drops a little on narrow beds; a 2 ft wide border at 12 in. spacing holds 2 rows, not 2.5.
- Vegetables in rows use two numbers: in-row spacing and row spacing (for access). Carrots at 3 in. in rows 12 in. apart is 4 per square foot, not 16.
- Buy 5-10% extra for a mass planting; losses at planting are normal and matching later is hard.
- Plugs versus pots: groundcover from 2 in. plugs at 8 in. spacing costs a quarter of gallon pots at 12 in. and fills in a season later.
Frequently Asked Questions
How many plants do I need for my bed?
Area in square feet ÷ (spacing in feet)². A 4 × 20 ft bed (80 sq ft) at 12 in. spacing takes 80 plants; at 18 in., 36; at 24 in., 20. Triangular (offset) planting fits about 15% more at the same spacing.
What is triangular spacing and why does it fit more?
Each row is offset by half a spacing from the one before, so plants sit at the corners of equilateral triangles instead of squares. Rows end up 0.866 × the spacing apart, which packs 15% more plants into the same area and closes the canopy faster -- the usual choice for groundcovers and mass plantings.
How many plants per square foot?
144 ÷ spacing in inches². At 4 in.: 9 per sq ft; 6 in.: 4; 8 in.: 2.25; 12 in.: 1; 18 in.: 0.44; 24 in.: 0.25. Square-foot gardening's grid of 1, 4, 9 or 16 per square is this table at 12, 6, 4 and 3 inches.
Should I space by the mature size or plant closer?
By mature size for shrubs and perennials, or you will be digging them out in three years. For annuals and vegetables the seed-packet spacing already assumes mature size within the season. Groundcovers are the exception: the label spacing is a compromise between cost and how fast you want cover, and closer is faster.
These calculators use published seeding rates, extension-service fertilizer guidance, and standard pool-chemistry dosing figures, and are for planning. Read the product label; it governs the dose. Pool chemicals are hazardous when mixed or mishandled, and a pool store's water test beats any estimate here.