Plant Spacing Calculator
Enter your bed's dimensions and a plant's recommended spacing to see how many you'll need, in a square grid or a more efficient triangular layout.
Layout plan
Planning a full bed
Spacing calculations are only as good as the shortlist behind them — start with the shade plant selector to find species suited to your zone, light, and moisture, note the spacing each one recommends, then run each through this calculator to compare plant counts (and cost) before you buy.
For moss and other true groundcover, the moss coverage calculator uses a dedicated patch-and-slurry model instead of row spacing, since moss establishes and spreads differently from potted perennials.
Frequently Asked Questions
Where do I find the right spacing number to enter?
Plant tags and nursery listings almost always give a recommended spacing — often as a range, like "12–18 inches." Use the wider end of the range for plants that will spread with age (many groundcovers and hostas) and the tighter end if you want a fuller look sooner and don't mind dividing plants later.
Why does the triangular layout fit more plants?
In a square grid, each plant sits directly above and beside its neighbours, leaving diamond-shaped gaps of unused space between four plants. A triangular (offset, or hexagonal) layout staggers alternating rows so each plant nestles into the gap of the row before it — the same spacing between neighbours, but roughly 15% more plants per unit area.
Does the calculator account for edge effects?
It uses simple floor-division on rows and columns, which is a standard planning approximation — real beds often fit one or two extra plants along an edge depending on the exact shape. Treat the total as a solid planning number and adjust slightly on-site for odd corners or curved edges.
Should groundcover use tighter spacing than a specimen perennial?
Generally yes — groundcover and mass plantings (moss, foamflower, wild ginger) are usually spaced at the tight end of their range, or even tighter, specifically so they knit together into a solid patch faster. A single specimen plant, like a hosta meant to stand out, is usually given its full mature spread.
Educational tool only. Plant counts are a planning estimate — irregular bed shapes and mature spread will shift the real number slightly.