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Seed Saving Calculator — Viability, Isolation & Storage

Save seeds like a pro with isolation distances and viability estimates

Seeds Needed

82

Mother Plants

6

Isolation

25 ft

Viability

4 yrs

Units

Seeds to Save

82

0.01 oz

Mother Plants

6

Seed Yield

600

Viability

4 yrs

Surplus

+518

Isolation & Storage

Isolation Distance25 ft
Drying Time7 days
Storage Temp40°F
Harvest Timing80 days after planting

What You'll Need

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Rain Bird SST600IN 6-Zone Sprinkler Timer

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Rapitest Premium Soil Test Kit 80 Tests pH NPK

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Scotts Turf Builder Lawn Food 5,000 sq ft

Scotts Turf Builder Lawn Food 5,000 sq ft

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Rain Bird SST600IN 6-Zone Sprinkler Timer

Rain Bird SST600IN 6-Zone Sprinkler Timer

$50-$704.3
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Rapitest Premium Soil Test Kit 80 Tests pH NPK

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Example Calculations

150 Tomato Plants, 2-Year Storage

Inputs

Crop FamilyNightshade
Desired Plants50
Germination85%
Years2

Result

Seeds Needed82
Mother Plants6
Isolation25 ft

Decay = 0.85^2 = 0.7225. Effective = 0.85 × 0.7225 = 0.614. Seeds = ceil(50 / 0.614) = 82.

220 Squash Plants, 1-Year Storage

Inputs

Crop FamilyCucurbit
Desired Plants20
Germination85%
Years1

Result

Seeds Needed28
Mother Plants6
Isolation800 ft

Decay = 0.85. Effective = 0.85 × 0.85 = 0.7225. Seeds = ceil(20 / 0.7225) = 28.

Frequently Asked Questions

Q

How many mother plants do I need for seed saving?

Save seeds from at least 6 plants for genetic diversity. Open-pollinated crops ideally need 20+ mother plants to maintain vigor over generations. Self-pollinating crops like tomatoes tolerate fewer mothers than cross-pollinators.

  • Minimum 6 mother plants per variety for basic diversity
  • Ideal: 20–50 plants for long-term seed stock
  • Self-pollinating crops (tomatoes, beans) tolerate fewer
  • Cross-pollinating crops (corn, squash) need 20+ plants
  • Mark best-performing plants early in the season
Q

How long do saved seeds last?

Alliums last only 1–2 years, while lettuce and cucurbits last 5–6 years stored cool and dry. Store at 40°F and below 8% moisture for maximum longevity.

  • Onion/leek: 1–2 years
  • Beans/peas: 3 years
  • Tomato/pepper: 4 years
  • Cucumber/squash: 5–6 years
  • Store below 40°F in airtight containers with silica gel
FamilyViabilitySeeds/ozIsolation
Nightshade4 yrs8,50025 ft
Cucurbit5 yrs300800 ft
Legume3 yrs10025 ft
Allium1 yr8,000800 ft
Q

What is isolation distance for seed saving?

Isolation distance prevents cross-pollination between varieties. Self-pollinating crops need only 10–25 feet, while wind and insect-pollinated crops need 800+ feet or physical barriers.

  • Tomatoes/peppers: 10–25 ft (self-pollinating)
  • Beans/peas: 10–25 ft (self-pollinating)
  • Squash/cucumber: 800–1,600 ft or hand-pollinate
  • Brassicas: 600–1,000 ft (insect-pollinated)
  • Corn: 1,000+ ft (wind-pollinated)
Q

How do I dry seeds for storage?

Wet seeds (tomato, cucumber) need fermentation first: soak 2–3 days, rinse, then air dry. Dry seeds (beans, lettuce) are harvested dry and need 1–2 weeks additional drying.

  • Wet processing: ferment 2–3 days then rinse and dry 5–7 days
  • Dry processing: harvest dry pods, thresh, winnow, dry 2 weeks
  • Seeds should snap, not bend, when fully dry
  • Silica gel packets maintain dryness in storage
  • Label with variety name, date, and germination test results

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Last Updated: Mar 21, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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