Bulb Spacing Calculator
Calculate bulb spacing with our free science calculator. Uses standard scientific formulas with unit conversions and explanations.
Reviewed by Daniel Agrici, Founder & Lead Developer
Formula
Grid: Bulbs = (floor(L/S)+1) x (floor(W/S)+1) | Staggered: Row spacing = S x sqrt(3)/2
For grid patterns, divide bed dimensions by spacing to get rows and columns. For staggered (triangular) patterns, alternate rows are offset by half the spacing, and row spacing is reduced by a factor of sqrt(3)/2 (approximately 0.866). Staggered patterns fit about 15% more bulbs in the same area while providing more natural coverage.
Worked Examples
Example 1: Tulip Bed Grid Layout
Problem:Plan a 12 ft x 5 ft tulip bed with 6-inch spacing in a grid pattern, planted 6 inches deep.
Solution:Length in inches: 12 x 12 = 144\nWidth in inches: 5 x 12 = 60\nRows = floor(60/6) + 1 = 11 rows\nBulbs per row = floor(144/6) + 1 = 25\nTotal bulbs = 11 x 25 = 275\nBed area = 12 x 5 = 60 sq ft\nDensity = 275/60 = 4.6 bulbs/sq ft\nSoil depth: 6 in = 0.5 ft, Volume = 60 x 0.5 = 30 cu ft
Result:275 tulip bulbs needed | 11 rows x 25 bulbs | 4.6 bulbs/sq ft | Est. cost: $82-$179
Example 2: Crocus Staggered Pattern
Problem:A 6 ft x 3 ft area for crocus with 4-inch spacing in staggered pattern, 3 inches deep.
Solution:Length = 72 in, Width = 36 in\nRow spacing (staggered) = 4 x sqrt(3)/2 = 3.46 in\nRows = floor(36/3.46) + 1 = 11 rows\nEven rows: floor(72/4) + 1 = 19 bulbs\nOdd rows: floor((72-2)/4) + 1 = 18 bulbs\nTotal = 6 x 19 + 5 x 18 = 114 + 90 = 204\nArea = 18 sq ft, Density = 11.3/sq ft
Result:204 crocus bulbs | 11 staggered rows | 11.3 bulbs/sq ft | Est. cost: $61-$133
Frequently Asked Questions
How do you determine the right spacing for bulbs?
The correct spacing depends on the bulb type and desired visual effect. A general rule is to space bulbs 2-3 times the bulb diameter apart, measured from center to center. Small bulbs like crocus need 3-4 inches, medium bulbs like tulips and daffodils need 4-8 inches, and large bulbs like dahlias need 18-24 inches. For a lush, full look in formal beds, plant at the closer end of the recommended range. For a more naturalized meadow look, use wider spacing. Bulbs planted too close together will compete for nutrients and water, resulting in smaller flowers over time. Most bulb packages include specific spacing recommendations.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy