HesapHanem

Bulb Planting Calculator

Enter your bed area and bulb spacing to find how many bulbs to plant.

How it is calculated

The tool assumes each bulb occupies a square of side equal to the spacing, laid out in a grid. Bed area is converted from square metres to square centimetres: area_cm² = area_m² × 10000. The count is bulbs = floor(area_cm² ÷ spacing²), rounded down to a whole bulb. The density line is 10000 ÷ spacing² bulbs per square metre, shown with one decimal. The spacing is the distance between bulb centres in cm, and the area is the planted area in m². Both must be above zero. The tool does not leave a margin at the bed edges and does not add a spare allowance, so buy a few extra if you want a reserve. Staggered planting fits slightly more.

Worked example

A bed of 4.5 m² planted with 12 cm between bulbs. Area in cm²: 4.5 × 10000 = 45,000. Space per bulb: 12 × 12 = 144 cm². Bulbs: 45,000 ÷ 144 = 312.5, rounded down to 312 bulbs. Density: 10000 ÷ 144 = 69.4 bulbs per m². At a tighter 8 cm spacing the same bed holds 703 bulbs, over twice as many, because the count depends on the square of the spacing.

Try this example →

Common mistakes

  • Entering the bed area in square feet or square centimetres. The field is in square metres, and 4.5 m² is 4.5, not 45000.
  • Entering the spacing as the bulb diameter or as the gap between bulbs. It is the distance from the centre of one bulb to the centre of the next.
  • Expecting the count to change in proportion to the spacing. Halving the spacing multiplies the number of bulbs by about four, not two.
  • Using one spacing for every kind of bulb. Large bulbs need more room than small ones, so calculate each kind separately if you mix them.
  • Ignoring the edge. The result assumes the whole area is planted, so subtract paths, shrubs and an edge margin from the area first.

About this calculator

Planting flower bulbs at the right density is mostly a matter of geometry: divide the bed's area by the space each bulb needs, and you get how many bulbs will fill it evenly. Spacing recommendations vary by bulb type and desired look — tulips and daffodils are typically spaced 10–15 cm apart for a naturalistic drift, while smaller bulbs like crocuses can be packed closer for a dense carpet of color.

This calculator takes your bed's area and your chosen bulb spacing and estimates how many bulbs to buy, saving a trip back to the garden center for more (or leftover bulbs going to waste). It's a practical tool for home gardeners and landscapers planning autumn bulb plantings, letting them budget the right quantity before digging a single hole.

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Comments (1)

  • Editorial team

    Bulb packaging often prints a recommended number per square metre, and the density line is the quickest way to compare with it: 10 cm spacing is 100 bulbs per square metre, and 15 cm is 44.4. If the label's figure is far from the density you chose, your spacing is probably different from the supplier's. For a drift look, you may plant fewer than the grid count, so the number here is an upper figure. Which bulbs are you planting, and at what spacing?

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