Enter Planting Details
Formula Used
Square layouts divide usable area by spacing multiplied by row spacing. Staggered layouts use a triangular packing factor of 0.866. Allowances and packet rounding determine the final purchase quantity.
| Layout | Core formula |
|---|---|
| Square or rows | Bulbs = usable area ÷ (spacing × row spacing) |
| Staggered or triangular | Bulbs = usable area ÷ (0.866 × spacing × row spacing) |
| Purchase quantity | Layout bulbs + allowances, rounded to complete packets |
| Container soil | Planter volume after drainage and unused depth deductions |
How to Use
Select a bed or container, then enter its dimensions. Choose a bulb preset or enter custom planting measurements. Review allowances, pricing, layers, and mixed-variety percentages before calculating.
- Choose the planting mode and desired calculation goal.
- Enter the bed, border, or container dimensions.
- Select the bulb, spacing, depth, and planting pattern.
- Add losses, packet sizes, prices, or mixed varieties.
- Calculate, review warnings, then export your results.
Example Planting Data
| Bulb | Typical spacing | Typical depth | Common season |
|---|---|---|---|
| Tulip | 12 cm | 15 cm | Autumn |
| Daffodil | 15 cm | 15 cm | Autumn |
| Crocus | 8 cm | 8 cm | Autumn |
| Hyacinth | 15 cm | 12 cm | Autumn |
| Lily | 25 cm | 18 cm | Autumn or spring |
| Allium | 20 cm | 15 cm | Autumn |
| Bulbous Iris | 10 cm | 10 cm | Autumn |
| Snowdrop | 7 cm | 7 cm | Autumn or in-the-green |
Supplier instructions should override these broad planning values. Soil, climate, and cultivar size can alter recommended depths. Confirm local guidance before completing large or expensive plantings.
Planting Tips and Common Mistakes
Keep the pointed end upward unless the bulb differs. Improve drainage before planting bulbs in heavy, wet ground. Avoid compressing soil directly above newly planted bulbs.
- Measure usable space after subtracting paths and permanent plants.
- Use wider spacing for naturalised displays and larger cultivars.
- Check mature spread, not only the bulb’s current diameter.
- Use complete packets when ordering to prevent shortages.
- Label mixed layers so later maintenance remains manageable.
Frequently Asked Questions
How accurate is the bulb quantity?
The estimate uses geometric spacing and usable planting area. Curves, roots, stones, and existing plants can reduce capacity. Add a sensible allowance before ordering your final quantity.
What does centre-to-centre spacing mean?
Spacing is measured between the centres of neighbouring bulbs. It prevents bulb diameter from distorting the layout calculation. Follow supplier distances when they provide cultivar-specific recommendations.
Why is staggered planting denser?
Staggered rows place bulbs within gaps between neighbouring rows. This arrangement uses space more efficiently than square grids. The calculator applies a triangular packing adjustment automatically.
How deep should bulbs be planted?
Many bulbs are planted two or three heights deep. Soil texture and bulb type can change that guidance. Always check the packet before planting valuable or unusual bulbs.
Can I calculate container bulb layers?
Yes, select container mode and choose multiple planting layers. Enter usable soil depth and vertical separation between layers. Warnings appear when the chosen layers may overlap.
How should mixed varieties be entered?
Add each variety with its percentage, spacing, and depth. The combined percentages should equal exactly one hundred percent. Quantities are allocated from the calculated layout total.
What allowance should I use?
Five to ten percent suits many ordinary projects. Increase it for uncertain quality or difficult conditions. Keep replacement bulbs only when their storage requirements permit.
Does the calculator include packet rounding?
Yes, required bulbs are rounded to complete packet quantities. This may create extra bulbs beyond your selected allowance. Use extras in containers or nearby naturalised groups.
Can it calculate from a fixed budget?
Choose budget mode and enter packet or bulb pricing. Delivery and percentage charges are included when supplied. The result estimates the maximum affordable bulb quantity.
Why might real soil volume differ?
Existing soil, settling, roots, and drainage materials affect volume. Container taper is approximated using a frustum calculation. Purchase slightly more mix for topping up after watering.
Are climate zones included?
The calculator provides general seasonal notes, not local forecasts. Frost dates and dormancy needs vary by region. Confirm recommendations with reliable local horticultural guidance.
Important Note
Results are planning estimates rather than horticultural guarantees. Bulb quality, drainage, climate, and supplier instructions can change outcomes. Verify local conditions before purchasing or planting substantial quantities.