Centre to centre. Use the mature width on the plant tag, not its pot size.
Quantity estimate for planning and buying. Rates vary by variety, region and product — check the label on what you actually buy.
How many plants do I need for a 10x20 ft bed?
A 10 x 20 ft bed (200 square feet) at 18 inch spacing takes 102 plants staggered, or 88 in a square grid.
At 12 inch spacing the same bed takes 230 staggered or 200 square; at 24 inches, 57 staggered or 50 square.
Staggered planting fits 15% more plants at the same centre-to-centre distance, closes the ground faster, and is how nurseries lay beds out. Square grids are easier to set out and weed between, which still makes them right for vegetable rows.
Square grid or staggered?
At the same centre-to-centre spacing, a staggered (triangular) layout fits 2/√3 = 1.1547 times as many plants into a bed as a square grid. That is 15% more plants in the same area with no plant any closer to its neighbour.
Each plant in a staggered layout sits in the gap between the two in the row behind, so the rows nest together. The row-to-row distance becomes 0.866 of the spacing rather than the full spacing, and the plants cover the ground faster and more evenly. It is how nurseries and landscapers lay out beds, and it is why a bed planted on a square grid looks sparser than the plant count suggests.
Square grids are easier to set out and easier to weed between, so they still make sense for vegetable rows and anywhere you need access lanes.
| Spacing | Square grid | Staggered | Row spacing |
|---|---|---|---|
| 4 in | 900 | 1039 | 3.5 in |
| 6 in | 400 | 461 | 5.2 in |
| 8 in | 225 | 259 | 6.9 in |
| 10 in | 143 | 166 | 8.7 in |
| 12 in | 100 | 115 | 10.4 in |
| 15 in | 64 | 73 | 13.0 in |
| 18 in | 44 | 51 | 15.6 in |
| 24 in | 25 | 28 | 20.8 in |
| 30 in | 16 | 18 | 26.0 in |
| 36 in | 11 | 12 | 31.2 in |
| 48 in | 6 | 7 | 41.6 in |
What spacing to use
Use the mature width from the plant label, not the size of the pot it came in. A perennial in a 4 inch pot that matures at 24 inches across wants 18-24 inch spacing, and it will look thin for two seasons. That is normal and correct.
| Plant type | Spacing | Per 100 ft² staggered |
|---|---|---|
| Annual bedding plants | 6-8 in | about 461 |
| Groundcover (pachysandra, vinca) | 8-12 in | about 259 |
| Perennials, small | 12-15 in | about 115 |
| Perennials, medium | 18-24 in | about 51 |
| Hosta, daylily | 18-24 in | about 51 |
| Small shrubs | 24-36 in | about 28 |
| Medium shrubs | 36-48 in | about 12 |
| Hedge plants (informal) | 18-24 in | about 51 |
Planting closer than the label
There are two legitimate reasons to plant tighter than the mature width: you want ground cover to close up within one season rather than three, or you are planting an annual display that will never reach mature size anyway.
The cost is real. Crowded perennials compete for water and nutrients, air circulates poorly between them, and fungal disease follows. If you plant at half the mature width, plan on dividing or thinning in two or three years — and for most perennials, dividing is free plants, so this is a reasonable trade rather than a mistake.
Common questions
How many plants do I need for a 10x20 ft bed?
At 18 inch spacing, 88 plants in a square grid or 102 staggered. At 12 inch spacing, 200 square or 230 staggered.
Does staggered planting really fit more plants?
Yes, 15.47% more at the same centre-to-centre spacing. Each plant sits in the gap between two in the row behind, so rows sit 0.866 of the spacing apart instead of the full spacing.
How far apart should I space groundcover?
8-12 inches for most spreading groundcovers like vinca or pachysandra. Closer gives faster coverage at higher cost; a staggered layout at 12 inches closes up about as fast as a square grid at 10.
What spacing do I use for hedge plants?
18-24 inches for an informal hedge, closer for a formal clipped one. Measure centre to centre, and use the plant mature width rather than its current size.