Plant Spacing Calculator
Calculates exact plant counts for flower beds and groundcover areas using either square grid layout or 15% denser triangular staggered equilateral layouts based on on-center spacing in inches.
Formula
Square Grid = Area ÷ (Spacing/12)²; Triangular = Square Grid × 1.155
1. Spacing in Feet = Spacing in ÷ 12 2. Square Grid Area per Plant = Spacing ft × Spacing ft 3. Base Plants (Square) = Area ÷ Square Area 4. Base Plants (Triangular) = Base Plants (Square) × 1.155 5. Total Plants with Waste = Ceil(Base Plants × (1 + Waste %))
Inputs
- Garden Bed Surface Area
- On-Center Plant Spacing
- Planting Pattern
Worked example
Planting 250 sq ft of periwinkle groundcover in a staggered triangular pattern at 12" spacing.
Outcome: Square grid rate is 1 plant/sq ft (250 plants). Staggered triangular pattern multiplies by 1.155 = 288.75 plants. Adding 5% nursery surplus gives 304 total plants (typically ordered as 6 flats of 48-count cell plugs).
Why does triangular plant spacing require ~15% more plants than square grid spacing?
In a triangular layout, each row is offset by half the spacing distance, bringing rows closer together (by a factor of √3/2 = 0.866). This eliminates diagonal empty space, requiring 15.5% more plants to cover the same square footage.