Bulb Spacing Calculator
Calculate exactly how many flower bulbs you need for any garden bed. Enter your planting area and recommended bulb spacing to get total bulb count, coverage layout, and estimated cost.
Bulb Spacing Calculator Tool
Why use this free bulb spacing calculator?
Built with the features most competitors miss — deeper inputs, benchmark data, and actionable guidance alongside the core calculation.
How to use this bulb spacing calculator
Spacing and depth by bulb type
| Bulb type | Spacing (in) | Planting depth | Blooms |
|---|---|---|---|
| Tulip | 4 to 6 | 6 to 8 inches | Spring |
| Daffodil | 4 to 6 | 6 to 8 inches | Spring |
| Crocus | 3 to 4 | 3 to 4 inches | Early spring |
| Hyacinth | 6 to 8 | 5 to 6 inches | Spring |
| Allium (large) | 6 to 10 | 4 to 8 inches | Late spring |
| Lily | 8 to 12 | 6 to 8 inches | Summer |
| Grape Hyacinth | 3 | 3 to 4 inches | Spring |
How this calculator compares
LazyTools fills the gaps most competing tools leave open — deeper analysis, benchmark context, and actionable guidance alongside the core calculation.
| Feature | LazyTools | OmniCalculator | GardenDesign.com | Longfield Gardens |
|---|---|---|---|---|
| Calculator (not just chart) | ✓ Yes | ✓ | ✗ | ✗ |
| Circle bed shape | ✓ Yes | ✓ | ✗ | ✗ |
| Triangular planting pattern | ✓ Yes | ✓ | ✗ | ✗ |
| Cost estimate output | ✓ Yes | ✓ | ✗ | ✗ |
| 10% wastage allowance | ✓ Yes | ✗ | ✗ | ✗ |
| Density per sq ft output | ✓ Yes | ✗ | ✗ | ✗ |
Bulb Spacing Calculator: Complete Guide
Calculating the right number of flower bulbs before you buy is one of the most practical steps in garden planning — it prevents the frustration of running short mid-planting or buying twice as many as needed. This calculator handles rectangular, circular, and custom-shaped beds with square and triangular planting patterns.
The bulb count formula
For square grid planting: Bulbs per sq ft = 1 / (spacing in ft) squared. For triangular (offset row) planting: Bulbs per sq ft = 1 / (spacing squared x 0.866). Multiply by total bed area in sq ft, then add 10% for edge wastage and filling gaps. This calculator applies all three steps automatically.
Spacing recommendations by species
Tulips and daffodils: 4 to 6 inches (formal beds) or 6 to 8 inches (naturalising). Crocus: 3 inches for carpeting effect, 4 to 5 inches for natural look. Hyacinths: 6 to 8 inches. Large alliums: 6 to 10 inches. Lilies: 8 to 12 inches. Smaller spacing creates a denser, more lush immediate display but requires more bulbs and can lead to overcrowding in subsequent years.
Square vs triangular planting patterns
Square grid planting places bulbs at equal distances in both directions, making it easy to lay out with a measuring tape. Triangular (quincunx) planting offsets alternate rows by half the spacing, creating a diamond pattern that looks more natural and uses bed space about 15% more efficiently. For formal beds and geometric designs, use square. For borders, mixed perennial beds, and naturalistic plantings, triangular gives a better result.
Planting depth for common bulbs
The standard rule is to plant bulbs at a depth of 2 to 3 times the bulb diameter. Large bulbs (tulips, daffodils, hyacinths): 6 to 8 inches deep. Medium bulbs (alliums, camassias): 4 to 6 inches. Small bulbs (crocus, grape hyacinths, snowdrops): 2 to 4 inches. In cold climates (zones 3 to 5), plant on the deep end of the range for insulation; in warmer zones (7 to 9), shallow planting helps the bulb experience cold temperatures.
Buying bulbs: quality indicators
Choose the largest bulbs in each size grade available — larger bulbs store more energy and produce bigger flowers in the first year. Look for firm, unblemished bulbs with dry, papery outer tunics. Avoid soft, mouldy, or lightweight bulbs. For tulips and daffodils, "double-nosed" or "double" bulbs have two growing points and will produce more flower stems per bulb in the first season.