Plant Spacing Calculator

On a square grid, each plant occupies spacing squared. Plants at 12 inches on centre each own 1 square foot, so a 100 sq ft bed takes 100 plants.

Offsetting alternate rows, triangular or staggered spacing, packs the same plants closer without crowding any individual one. Each plant then occupies spacing² × 0.866, where 0.866 is √3⁄2, the row-offset factor. That fits about 15.5% more plants into the same area.

Nurseries and landscapers use triangular spacing for groundcover because it closes canopy faster and leaves no visible rows. For a formal hedge or a vegetable bed you want rows you can walk, so square or row spacing makes more sense.

Space plants for what they will become, not what arrived in the tray. A gallon-pot hydrangea looks lost at 5 ft centres and looks correct three years later; planted at 2 ft it becomes a tangled mass you will have to thin.

The exception is groundcover, where the point is fast coverage and the planting is meant to merge. Tightening groundcover spacing genuinely buys you a season of establishment time.

Planting a line rather than filling an area uses different math: length divided by spacing, plus one for the end plant. A 40 ft hedge at 18 inch spacing takes 27 plants, not 26.

For a screening hedge, tighten spacing to about two thirds of the plant's mature width so the canopy closes. Arborvitae rated at 4 ft wide goes in at roughly 3 ft centres for a solid screen.