Formula used
Plants per row = floor(row length ÷ plant spacing) + 1
Adjusted plugs = field target ÷ nursery survival ÷ transplant survival
Seeds required = adjusted plugs × seeds per cell ÷ germination rate
Spacing defines each planting position. Survival rates increase nursery production. Reserve seedlings protect schedules from unexpected establishment losses today.
How to use
Select a calculation mode. Enter realistic spacing and survival rates. Review every result before purchasing seeds, trays, or media.
- Choose planting area, rows, trays, succession, or multi-crop mode.
- Select units, crop spacing, layout, and establishment percentages.
- Add tray, water, labour, packet, and cost information.
- Calculate, then copy, export, or print the results.
Worked example
A grower needs five hundred transplants. Germination is ninety percent. Loss allowances increase seeds, plugs, trays, and total costs.
| Input | Example value | Purpose |
|---|---|---|
| Final transplant target | 500 | Desired field population |
| Germination rate | 90% | Expected seed germination |
| Nursery survival | 95% | Expected healthy plugs |
| Transplant survival | 95% | Expected field establishment |
| Tray size | 72 cells | Tray quantity calculation |
Plant spacing reference
| Crop | Plant spacing | Row spacing |
|---|---|---|
| Tomato | 45 cm | 75 cm |
| Pepper | 35 cm | 50 cm |
| Lettuce | 25 cm | 30 cm |
| Cabbage | 45 cm | 60 cm |
| Broccoli | 45 cm | 60 cm |
| Onion | 10 cm | 25 cm |
| Spinach | 10 cm | 25 cm |
| Cucumber | 45 cm | 90 cm |
| Melon | 90 cm | 150 cm |
| Mixed herbs | 20 cm | 25 cm |
| Bedding flowers | 20 cm | 25 cm |
Assumptions and limitations
Results remain planning estimates. Seed quality and conditions vary. Confirm commercial decisions using local crop guidance and records.
Frequently asked questions
What does this seedling calculator estimate?
It estimates plants, seeds, trays, media, water, labour, and costs. It supports several planting methods. Results help organise nursery and field preparation.
Why include germination rate?
Not every seed germinates successfully. Lower rates require more seed. Use tested values from current seed lots.
What is nursery survival?
Nursery survival measures usable seedlings after germination. Disease and handling reduce survival. Use recent records for reliable planning.
Why add reserve seedlings?
Reserve plants replace damaged or weak transplants. Weather can increase losses. A modest reserve protects planting schedules.
How does staggered spacing work?
Staggered rows place plants between neighbouring gaps. This raises planting density. The calculator applies a triangular pattern factor.
Can it calculate succession plantings?
Yes, enter dates and interval days. The tool counts planting batches. It then totals all required seedlings.
Can I compare multiple crops?
Yes, divide one area among three crops. Shares must total one hundred percent. Each crop uses separate spacing values.
How is potting mix calculated?
Cell volume multiplies total tray cells. Extra media covers filling losses. The result appears in litres.
Are costs exact?
No, costs are planning estimates. Prices and labour vary. Update every cost field before budgeting.