Greenhouse Coverage Calculator
Planning greenhouse capacity before purchasing plugs or starts prevents crowding and expensive restocking. This calculator divides usable greenhouse floor area by the per-plant footprint to give the maximum number of plants at your chosen on-center spacing. A utilization factor accounts for walkways, bench frames, and other non-growing area. The default utilization of 70% reflects typical commercial greenhouse configurations, but you can adjust it for your layout. Spacing recommendations follow USDA Cooperative Extension greenhouse production guides.
Greenhouse coverage formula
Usable area (sq ft) = Length x Width x (Utilization% / 100)
Area per plant (sq ft) = (Spacing (in) / 12)^2
Plants = floor(Usable area / Area per plant)
For square on-center spacing, each plant occupies a square with side equal to the spacing distance. Divide spacing in inches by 12 to convert to feet before squaring.
Typical on-center spacings
- Herb transplants, small annuals: 6 to 8 inches.
- Bedding plant flats, petunias: 10 to 12 inches.
- Tomatoes, cucumbers: 18 to 24 inches.
- Hanging baskets: 24 to 30 inches (to prevent shading).
- Poinsettias (final spacing): 14 to 16 inches per pot diameter of 6 inches.
Greenhouse coverage calculator: frequently asked questions
How many plants fit in a 10 x 20 greenhouse?
A 10 x 20 ft greenhouse has 200 sq ft. With 1 sq ft per plant (12-inch spacing), you fit 200 plants. At 4 sq ft per plant (24-inch spacing), you fit 50 plants. This calculator divides total area by the area per plant.
How much space does each plant need?
Herbs and small transplants: 4 to 6 inches center to center (0.11 to 0.25 sq ft). Tomatoes, peppers: 18 to 24 inches (2.25 to 4 sq ft). Cucumbers: 12 to 18 inches (1.0 to 2.25 sq ft). These figures reflect USDA Cooperative Extension greenhouse production recommendations.
Should I account for walkways?
Yes. Walkways in commercial greenhouses typically occupy 20 to 30 percent of floor area. Subtract walkway area before calculating, or apply a utilization factor of 0.70 to 0.80. The calculator includes an optional utilization factor field for this purpose.
What is a pot footprint vs. on-center spacing?
On-center spacing is the distance between the centers of adjacent plants. The area per plant equals spacing squared (for square spacing) or 0.866 times spacing squared (for triangular offset spacing). Square spacing is simpler and used here.
How do I convert pot diameter to square feet per plant?
For square bench spacing, area = pot diameter (in inches) squared, divided by 144. A 6-inch pot at minimum spacing needs 6 x 6 = 36 sq in = 0.25 sq ft. In practice, add 2 to 4 inches to the pot diameter to get the on-center spacing for air circulation.
Official sources
- USDA National Institute of Food and Agriculture, greenhouse production: nifa.usda.gov.
- USDA Agricultural Research Service: ars.usda.gov.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.