Vegetable Seed Calculator
Compute vegetable seed using validated scientific equations. See step-by-step derivations, unit analysis, and reference values.
Formula
Seeds = ceil((Plants x Seeds/Hole) / Germination Rate)
Total planting positions are calculated by dividing row length by plant spacing and multiplying by the number of rows. Seeds needed equals positions multiplied by seeds per hole, divided by the germination rate (as a decimal). This ensures enough seeds to achieve the desired plant population despite germination losses.
Worked Examples
Example 1: Tomato Garden Seed Calculation
Problem: Calculate seeds needed for 3 rows of tomatoes, each 10m long, with 60cm spacing, 2 seeds per hole, and 85% germination.
Solution: Plants per row = floor(10 / 0.6) + 1 = 17 plants\nTotal planting positions = 17 x 3 = 51 positions\nSeeds needed = ceil((51 x 2) / 0.85) = ceil(120) = 120 seeds\nSeed weight = 120 / 300 seeds per gram = 0.4 grams\nStandard packet (~2g) has ~600 seeds = 1 packet is plenty
Result: 120 seeds needed | 0.4 grams | 1 seed packet sufficient
Example 2: Carrot Bed Direct Sowing
Problem: Direct sow carrots in 5 rows, each 3m long, 5cm spacing, 3 seeds per hole, 75% germination rate.
Solution: Plants per row = floor(3 / 0.05) + 1 = 61 positions\nTotal positions = 61 x 5 = 305 positions\nSeeds needed = ceil((305 x 3) / 0.75) = ceil(1220) = 1,220 seeds\nSeed weight = 1220 / 800 seeds per gram = 1.5 grams\n1 standard packet (2g = ~1,600 seeds) is sufficient
Result: 1,220 seeds needed | 1.5 grams | 1 seed packet
Frequently Asked Questions
What is succession planting and how does it affect seed needs?
Succession planting means sowing the same crop at regular intervals (typically every 2-3 weeks) to ensure a continuous harvest rather than one large harvest all at once. This is especially valuable for quick-maturing crops like lettuce, radishes, spinach, and beans. For example, instead of planting 60 lettuce plants at once, plant 15 every two weeks for 8 weeks. This approach multiplies your total seed needs by the number of plantings but provides fresh produce over a much longer period. Not all crops benefit — tomatoes, peppers, and squash produce over a long season from a single planting.
How long do vegetable seeds stay viable?
Seed longevity varies by species when stored in cool, dry conditions. Onion and parsnip seeds last only 1-2 years. Corn, pepper, and lettuce seeds last 2-3 years. Tomato, cucumber, and bean seeds can last 3-5 years. Radish and beet seeds remain viable for 4-5 years. To test old seeds, place 10 seeds on a damp paper towel in a sealed plastic bag and keep warm for a week. Count how many germinate — if 7 out of 10 sprout, the germination rate is 70%. Store seeds in airtight containers in a cool (40-50F), dark, and dry location for maximum longevity.
Does Vegetable Seed Calculator work offline?
Once the page is loaded, the calculation logic runs entirely in your browser. If you have already opened the page, most calculators will continue to work even if your internet connection is lost, since no server requests are needed for computation.
How accurate are the results from Vegetable Seed Calculator?
All calculations use established mathematical formulas and are performed with high-precision arithmetic. Results are accurate to the precision shown. For critical decisions in finance, medicine, or engineering, always verify results with a qualified professional.
How do I get the most accurate result?
Enter values as precisely as possible using the correct units for each field. Check that you have selected the right unit (e.g. kilograms vs pounds, meters vs feet) before calculating. Rounding inputs early can reduce output precision.
Can I share or bookmark my calculation?
You can bookmark the calculator page in your browser. Many calculators also display a shareable result summary you can copy. The page URL stays the same so returning to it will bring you back to the same tool.