Biology & Life Science

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Bulb Spacing Calculator.

Estimate bulbs for a rectangular planting bed from your dimensions, spacing, and waste allowance.

On-device calculationNo signup
01

Set your values

Results update as you type.

Rows: 10

Rows

10
Bulbs per row: 8

Bulbs per row

8
Required bulbs: 84

Required bulbs

84

How to Use

Rows = floor(bed length ÷ row spacing); bulbs per row = floor(bed width ÷ in-row spacing); add the entered waste percentage.

Use a named source for any material-specific coefficient. This page does not infer local rates, species tables, laboratory methods, or safety guidance.

Use Cases

Plan a new flower bed

Determine how many bulbs to purchase for a new rectangular garden bed by entering your bed dimensions and desired spacing.

Example: A 4m x 2m bed with 0.15m row and in-row spacing needs about 356 bulbs (with 10% waste).

Budget for a large planting project

Get an accurate bulb count to estimate costs and avoid over- or under-ordering for community or commercial plantings.

Example: For a 10m x 5m bed with 0.2m spacing and 5% waste, the calculator shows 1,313 bulbs.

Frequently Asked Questions

How does the Bulb Spacing Calculator estimate the number of bulbs?
It calculates the number of bulbs by dividing the bed area by the product of row spacing and in-row spacing, then adds a waste allowance percentage to account for planting errors or damaged bulbs.
What is the waste allowance for in the bulb spacing calculation?
The waste allowance is a percentage you can set to cover extra bulbs needed for replacements due to breakage, disease, or planting mistakes. It ensures you order enough bulbs for a full bed.
Can I use this calculator for any bulb type?
Yes, as long as you know the recommended row and in-row spacing for your specific bulb type. The calculator works for any bulb planted in a rectangular grid pattern.

Tips & Common Mistakes

Tips

  • Measure your bed accurately in meters, including any curves or irregular edges, to get a reliable estimate.
  • Check the recommended spacing for your specific bulb type; smaller bulbs like crocus need closer spacing than tulips.
  • Add a waste allowance of 5-10% to cover damaged bulbs or planting errors, especially for large orders.
  • Use the result as a guide; actual planting may vary based on soil conditions and bulb size.

Common Mistakes to Avoid

  • Forgetting to convert bed dimensions to meters if you measured in feet or inches, leading to incorrect bulb counts.
  • Using the same spacing for all bulb types without checking specific requirements, which can result in overcrowding or sparse planting.
  • Setting waste allowance to 0% and then running short when some bulbs fail to sprout.

Last updated: August 13, 2026