Plant & Ground Cover Spacing Calculator

The count uses the area-density model: a square grid fits 144 / X² plants per square foot, where X is the on-center spacing in inches (144 in² per sq ft). A triangular (staggered) layout multiplies that by 1.155 — the equilateral-triangle lattice (row pitch X × 0.866) packs about 15% more plants at the same spacing. We multiply by your bed area and round the count up so you never under-buy.

density (square grid) = 144 / X²            (X = spacing in inches)
density (triangular)  = density × 1.155     (row pitch = X × 0.866)

plants (square)     = ceil(area_sqft × density_grid)
plants (triangular) = ceil(area_sqft × density_tri)

buy quantity = ceil(selected count × (1 + waste%))
material cost = buy quantity × price/plant   (when a price is entered)

The plants-per-sq-ft density is an estimate: the area model slightly overcounts on small or irregular beds (it ignores edge effects), so treat it as a starting buy quantity and adjust to the bed. Spacing ranges (12–24 in O.C. for ground covers) are general reference, not a species-specific mandate. Prices are your own input — no national price is asserted.