Plant Spacing Calculator
Calculate how many plants a bed needs at a given spacing on center, in a square grid or staggered rows, with plants per square foot, rows and flats to buy.
By CalcBuilt Editorial TeamUpdated September 9, 2026Formulas checked against manufacturer specs, see how we calculate.
Results
- Plants needed
- 185 plants
- 160 sq ft at 12 in on center, staggered
- Plants per square foot
- 1.15 per sq ft
- Square grid density divided by 0.866, about 15% more plants
- Rows and plants per row
- 9 rows of 20
- 176 plants land inside the bed with the first row 6 in off the edge; the count above carries the spares that edges and curves eat. Every other row holds one fewer plant
- Flats to buy
- 11 flats of 18
- 13 spare plants; keep them potted for the gaps that show next spring
Plant Spacing formula
Plants per sq ft = 144 / spacing² (square grid)
Plants per sq ft = 144 / (spacing² x 0.866) (staggered rows)
Plants = Bed length x Bed width x plants per sq ft
Rows = (Bed width x 12 - 2 x edge offset) / row spacing + 1Worked example
A 30 x 10 ft bed of liriope at 18 in on center, staggered: 144 / (18 x 18 x 0.866) = 0.513 plants per square foot. 30 x 10 = 300 square feet, and 300 x 0.513 = 154 plants. At 32 cells per flat that is 5 flats.
The grid check: rows sit 18 x 0.866 = 15.6 in apart, so a 120 in wide bed with the first row 9 in off the edge fits 7 rows, and a 360 in long bed fits 20 plants per row. Staggered, that is 137 plants inside the bed. Order the 154 and use the spares along the curved front edge.
Quick reference
| Spacing on center | Square grid | Staggered rows | Flats of 18 (staggered) |
|---|---|---|---|
| 6 in | 400 | 462 | 26 |
| 8 in | 225 | 260 | 15 |
| 10 in | 144 | 167 | 10 |
| 12 in | 100 | 116 | 7 |
| 18 in | 45 | 52 | 3 |
| 24 in | 25 | 29 | 2 |
| 36 in | 12 | 13 | 1 |
Spacing comes off the tag, not the pot
Every spacing decision starts with the mature spread printed on the plant tag. A plant sold in a 4 in pot that spreads 24 in gets 24 in of room, and the bed looks thin for two seasons. Nurseries space ground covers tighter than the mature spread on purpose, because bare soil grows weeds: vinca and pachysandra go in at 8 to 12 in, liriope and hosta at 12 to 18 in, daylilies at 18 to 24 in. WSU Extension sets the rule for anything larger, including shrubs: the distance between two plants is half of one mature spread plus half of the other, so an 8 ft shrub sits about 7 ft from a 6 ft one.
Hedges and specimens follow different rules. A hedge has to close, so low hedge plants 3 to 4 ft tall go about 18 in apart and tall hedge plants 3 to 4 ft apart. A specimen shrub is meant to be seen whole, so it gets its full mature width plus room to walk around it. Against a foundation, small shrubs sit at least 2 ft out, medium shrubs 3 ft and tall shrubs 4 to 5 ft, measured from the wall to the trunk.
Square grid or staggered rows
A square grid puts every plant on a 12 in checkerboard: easy to lay out with a string line and a spacing stick, and easy to walk between. It also leaves a diamond of bare soil in the middle of each square, which is where the weeds start. Staggered rows offset every other row by half a spacing, so the rows sit 0.866 of the spacing apart and each plant keeps the same distance from six neighbors. That fits about 15 percent more plants in the same bed and closes the canopy roughly a season sooner. Illinois Extension recommends the staggered or diamond pattern for ground covers.
Lay it out before you dig. Mark the first row half a spacing in from the edge, set a row of plants still in their pots, then step the next row back by 0.866 of the spacing and slide it over by half a spacing. Check the far end of the bed before anything goes in the ground, because a curve that swallows two plants per row is easier to fix with pots than with holes. Plant on the flat, water each plant in as you go rather than at the end, and expect a bed at label spacing to take two growing seasons to close.
What this calculator leaves out
Soil prep, which is the part that decides whether the bed fills in: Illinois Extension calls for tilling 6 to 8 in deep with organic matter and killing perennial weeds before planting, not after. Also mulch at 1 to 2 in over new plugs, a starter fertilizer, edging, drip line or a soaker hose for the first two summers, and delivery. Slopes need the bed mulched or netted right after planting so the first storm does not wash the plugs downhill.
Mistakes that cost money
- Spacing to the pot size instead of the mature spread: a 4 in pot of a plant that spreads 24 in ends up at triple the count you need.
- Running the first row on the bed edge: the plants flop onto the walk within two seasons; hold the row back half a spacing.
- Ordering flats instead of plants: 18 cell and 32 cell flats are different plant sizes, so the count per flat changes the price per square foot.
- Landscape fabric under a running ground cover blocks the stolons from rooting, so the bed never knits and the fabric surfaces.
- Mulching 3 in deep over new plugs buries the crowns; keep it 1 to 2 in and pull it back off each plant.
- Spacing shrubs at their tag width but setting them 2 ft off the house: the spread is measured from the trunk, so half of it lands on the siding.
Key facts
- At 12 in on center a square grid holds exactly 1 plant per square foot; staggered rows at the same spacing hold 1.15.
- The Illinois Extension ground cover chart calls for 400 plants per 100 sq ft at 6 in spacing, 100 at 12 in and 45 at 18 in.
- WSU Extension puts it in reverse: 100 plants cover about 25 sq ft at 6 in spacing, 100 sq ft at 12 in and 400 sq ft at 25 in.
- Low hedge plants 3 to 4 ft tall go about 18 in apart; tall hedge plants go 3 to 4 ft apart (WSU Extension C132).
- Ground cover plugs typically cost under $1.50 each in tray quantities in 2026 US retail, against $3 to $6 for the same plant in a 4 in pot.
Frequently asked questions
How many plants do I need per square foot?
At 12 in on center, 1 plant per square foot in a square grid and 1.15 in staggered rows. At 6 in it is 4 and 4.6, at 18 in it is 0.44 and 0.51, and at 24 in it is 0.25 and 0.29.
Is triangular spacing better than a square grid?
For ground covers, yes. Staggered rows fit about 15 percent more plants in the same bed and close the bare diamonds a square grid leaves, so weeds get less time. For shrubs and anything you have to walk between, a square grid is easier to lay out and maintain.
How far from the edge of the bed should the first row go?
Half the spacing. At 12 in on center that is 6 in, which lets the plants fill to the edge without hanging over the walk or getting cut by a string trimmer.
How long before a ground cover fills in?
Two growing seasons at label spacing for spreaders like vinca and pachysandra, three or more at 24 in spacing or with clumping plants that never run. Mulch 1 to 2 in and pull weeds by hand until the canopy closes; nothing fills a bed faster than tighter spacing.
Sources and references
- Ground Covers: spacing chart and staggered planting pattern (University of Illinois Extension)
- Spacing of Landscape Plants (C132) (Washington State University Extension)
Next steps for this project
The usual order for a landscaping & outdoor project. See all landscaping & outdoor calculators.
Results are estimates based on standard formulas and typical product specifications. Confirm quantities with your supplier and local code before ordering.