Vegetable Seed Calculator

About the Vegetable Seed Calculator

Planning a vegetable garden starts with a deceptively simple question: how many seeds do you need? The answer depends on the vegetable, planting method, spacing, germination rate, and whether you're direct sowing or transplanting. Order too few and you'll have gaps; order too many and seeds go to waste (or worse, you overcrowd beds trying to use them all).

Seed packets list "seeds per packet" ranging from 10 (expensive hybrid tomatoes) to 1,000+ (carrots, lettuce). But converting packet counts to garden reality requires knowing seeds per row foot, germination rates, thinning ratios, and timing for succession plantings. A 100-foot row of carrots at 20 seeds per foot needs 2,000 seeds — one packet. The same 100 feet of tomatoes at 2-foot spacing needs only 50 transplants, started from perhaps 75 seeds to account for germination losses.

This calculator covers 30+ common vegetables with species-specific data for spacing, germination rates, seeds per ounce, and yield per plant. Enter your row length or bed area, select your vegetables, and get exact seed counts with packet and succession planting calculations. It factors in thinning overhead, indoors-vs-direct sowing differences, and estimated harvest yields so you can plan a productive garden from seed order to harvest.

When This Page Helps

Seed ordering is one of the first steps in garden planning. Getting accurate counts for each vegetable prevents waste, ensures full beds, and enables proper succession planting for extended harvests throughout the growing season.

How to Use the Inputs

1. Select your vegetable from the preset list
2. Enter the row length or bed area for that vegetable
3. Choose direct sowing or transplant method
4. Set the number of succession plantings (for extended harvest)
5. Add a germination/loss factor for extra seeds
6. Review seed quantity, packet needs, and yield estimate
7. Repeat for each vegetable in your garden plan

Example Calculation

Tips & Best Practices

• Order 15-25% more seed than the minimum to cover poor germination and thinning losses
• Store unused seeds in a sealed container in the refrigerator for longest viability
• Sow fine seeds (carrots, lettuce) by mixing with sand for more even distribution
• Label everything — seed varieties look identical once removed from packets
• Plan succession plantings for salad greens every 2-3 weeks from spring through fall
• Buy pelleted/coated seeds for tiny-seeded crops (carrots, lettuce) — much easier to space

Seed Starting Timeline

Start seeds indoors on a schedule based on your last frost date. **8-10 weeks before**: peppers, eggplant, onions. **6-8 weeks**: tomatoes, broccoli, cabbage, cauliflower. **4-6 weeks**: lettuce, herbs, cucumbers, squash. **2-4 weeks**: melons, beans (optional). Each vegetable has an optimal window — starting too early creates leggy, root-bound transplants; too late means missing the growing season. Use your USDA hardiness zone and local frost dates to build a personalized calendar.

Yield Expectations per Plant

A single tomato plant produces 10-15 lbs of fruit. One zucchini plant: 6-10 lbs (and you'll be giving it away). One pepper: 5-10 peppers. One head of lettuce: 0.5-1 lb. 1 row foot of carrots: 1-2 lbs. 1 row foot of beans: 0.5-1 lb per picking. These numbers help you decide how many plants you actually want — most families only need 4-6 tomato plants but appreciate 50+ row feet of salad greens for succession harvesting.

Seed Saving Economics

A packet of hybrid seeds costs $3-6 and contains 20-50 seeds. Open-pollinated (heirloom) varieties can be saved from year to year, eventually eliminating seed costs for those crops. To save seeds legally and biologically: grow only open-pollinated varieties, isolate from cross-pollination (especially corn, squash, brassicas), select from your best-performing plants, dry thoroughly, and store in a cool, dry place. After 2-3 years of selecting for your local conditions, saved seeds often outperform purchased ones.

Frequently Asked Questions

• How many seeds should I start per cell?

  Start 2-3 seeds per cell for most vegetables to ensure at least one germination. Thin to the strongest seedling after they develop true leaves. For expensive seeds (organic heirloom tomatoes at $0.25+/seed), start 1-2 per cell.

• What's succession planting?

  Succession planting means sowing the same crop multiple times at intervals (every 2-3 weeks) for an extended harvest instead of one big glut. It's essential for lettuce, radishes, beans, and other short-season crops. Without succession planting, your entire lettuce crop matures in one week.

• How long do vegetable seeds last?

  Most seeds last 2-4 years stored in a cool, dry place. **Short-lived (1-2 years)**: onions, parsnips, leeks. **Medium (3-4 years)**: beans, carrots, peas, peppers. **Long-lived (4-6 years)**: tomatoes, cucumbers, melons, brassicas. Test old seeds by sprouting 10 on a wet paper towel.

• Should I direct sow or start transplants?

  Direct sow: beans, peas, corn, carrots, radishes, beets, squash (root crops and large seeds). Start transplants: tomatoes, peppers, eggplant, broccoli, cabbage (warm-season crops in short-season areas). Either way: lettuce, cucumbers, melons.

• How many row feet of vegetables do I need per person?

  General guidelines per person: tomatoes 5-10 plants, peppers 3-5, lettuce 10-15 row feet, beans 15-20 row feet, carrots 10-15 row feet, squash 2-4 plants. Double these for preserving and canning.

• How do I calculate seeds for a raised bed?

  Convert bed area to row feet: a 4×8 bed has 32 square feet. For row crops, divide width by row spacing to get number of rows, multiply by bed length. For intensive/block planting, use the plants per square foot guide.