Bulb Spacing Calculator

• Always include a border

  A border of 5–15 cm (2–6 inches) keeps bulbs away from the bed edge and creates a more natural look. Without a border, the calculator places bulbs right up to the perimeter, which can look cramped.

• Try both grid types before buying bulbs

  The triangular grid packs 10–15% more bulbs into the same area. If you are on a budget, the rectangular count tells you the minimum. If you want maximum impact, go with the triangular count.

• Account for bulb size

  Large bulbs (daffodils, tulips, allium) need more space than small ones (crocus, muscari, snowdrops). The pre-set spacings in the calculator reflect best practices from horticultural sources. If you are planting particularly large or small specimens, adjust the spacing in the "Custom plant" mode.

• Layer bulbs for season-long color

  Plant small, early-blooming bulbs (crocus, snowdrops) above later-blooming ones (tulips, allium) in the same bed. Use the calculator for each layer separately, then plant at different depths. This technique, called "lasagne planting," maximizes your display from early spring through summer.

• Order 5–10% extra bulbs

  Not every bulb will survive or bloom. It is good practice to order slightly more than the calculated count. Use the excess to fill gaps or create container displays. The calculator gives a solid baseline — add a buffer for real-world losses.

Key variables

• $L$: bed length, $W$: bed width, $B$: border distance
• $P_s$: plant spacing (distance between plants in a row), $R_s$: row spacing (distance between rows)
• Usable length: $U_L = L - 2B$, usable width: $U_W = W - 2B$

Rectangular grid

In a rectangular grid, plants are aligned in rows and columns. The number of plants is the product of how many fit along the length and how many fit along the width.

The $+1$ accounts for the first plant at the starting edge. The floor function ensures we count whole plants only.

Triangular (staggered) grid

A triangular grid staggers every other row, allowing plants to fit more densely. The vertical spacing between rows is reduced by a factor of approximately$\sqrt{3}/2 \approx 0.866$.

First, calculate the number of triangular rows:

Then, count plants in odd and even rows:

Total triangular plants:

Rectangular vs triangular planting

The choice between rectangular and triangular grids is not just about maximizing numbers — it also affects how the planting looks. Rectangular grids create clean, geometric lines that work well for formal gardens and crop rows. Triangular grids give a more natural, organic feel that blends into informal beds and borders.

Understanding bulb spacing recommendations

Spacing recommendations vary by bulb type and depend on the mature size of the plant. Small bulbs like crocus and muscari can be planted 5–8 cm apart, while large bulbs like daffodils and tulips need 10–20 cm. The pre-set values in the calculator come from horticultural best practices, but you can always override them in "Custom plant" mode.

If you are planning a mixed border with non-bulb perennials and shrubs, you can apply similar spacing principles using the "Custom plant" option.

Lasagne planting (layering bulbs)

Lasagne planting means layering different bulbs at different depths in the same container or bed. Early-blooming crocus and snowdrops go on top (shallow), mid-season tulips and daffodils in the middle, and late-blooming allium at the bottom. Each layer uses the same surface area, so you can use the calculator once and plant multiple layers at different depths.

This technique works beautifully in patio pots and window boxes. Just make sure each layer has enough depth — the calculator handles the surface area, you handle the depth.