Community Seed Bank Management
Seeds are the foundation of food security. A community that loses its seed stock loses its ability to feed itself. A community seed bank is not a luxury — it is critical infrastructure, on par with the water supply and the grain mill. It preserves genetic diversity, ensures planting stock for every season, and serves as insurance against crop failure.
What Can Be Saved
Open-Pollinated (OP) vs Hybrid
Open-pollinated varieties: seeds saved from these plants produce offspring true to type (or very close). These are the only varieties suitable for long-term seed saving.
Hybrid (F1) varieties: seeds from hybrid plants produce unpredictable offspring — some reverting to parent traits, some producing poorly or not at all. Hybrid seed cannot be reliably saved.
Post-collapse, all agriculture must transition to open-pollinated varieties as quickly as possible. Every hybrid variety in your garden is a dead end unless you can locate the parent lines and recreate the cross.
Self-Pollinating vs Cross-Pollinating
This distinction determines how difficult seed saving is:
Self-pollinating (easy to save — minimal isolation needed):
- Tomatoes, peppers, beans, peas, lettuce, wheat, oats, barley
- The flower pollinates itself before opening. Different varieties can grow near each other with minimal crossing.
Cross-pollinating (requires isolation or controlled pollination):
- Corn, squash, brassicas (cabbage, broccoli, kale), beets, onions, carrots
- Insects or wind carry pollen between varieties, producing crosses. You must isolate varieties to keep seed pure.
Seed Harvest Timing
Seeds must be fully mature before harvest — immature seeds will not germinate or will produce weak seedlings.
Dry-Seeded Crops (seed dries on the plant)
| Crop | Harvest Sign | Method |
|---|---|---|
| Beans/peas | Pods brown and dry, rattle when shaken | Pull whole plants, hang to finish drying |
| Grains (wheat, corn, oats) | Heads golden, grain hard when bitten | Cut heads, thresh, winnow |
| Lettuce | Seed heads fluffy (like dandelion) | Cut heads into paper bag, shake |
| Sunflower | Back of head brown, seeds dark | Cut head, dry indoors, rub out seeds |
| Herbs (dill, coriander) | Seed heads brown and dry | Cut into bag, shake loose |
Wet-Seeded Crops (seed inside fruit)
| Crop | Harvest Sign | Method |
|---|---|---|
| Tomato | Fruit fully ripe (overripe is fine) | Scoop seeds, ferment 2-3 days, rinse, dry |
| Squash/pumpkin | Fruit fully mature (hard rind, stem dry) | Scoop seeds, wash off pulp, dry |
| Cucumber | Fruit overripe (yellow/orange) | Scoop seeds, ferment briefly, rinse, dry |
| Pepper | Fruit fully ripe (red/orange stage) | Cut open, scrape seeds, dry |
| Melon | Fruit fully ripe | Scoop seeds, rinse, dry |
The Fermentation Step (Tomatoes, Cucumbers)
Fermentation removes the gel coating that inhibits germination and kills some seed-borne diseases:
- Scoop seeds and pulp into a jar with a small amount of water
- Cover loosely (not sealed — fermentation produces gas)
- Stir daily. A layer of mold on top is normal and expected.
- After 2-3 days, viable seeds sink to the bottom. Dead seeds and pulp float.
- Pour off floating material, rinse good seeds, spread on paper plate to dry completely
Isolation Distances
To prevent unwanted crossing, different varieties of the same cross-pollinating species must be separated.
| Crop | Minimum Isolation Distance | Notes |
|---|---|---|
| Corn | 1/4 mile (400m) minimum, 1/2 mile preferred | Wind-pollinated, crosses very easily |
| Squash (same species) | 1/2 mile (800m) | Bee-pollinated; or hand-pollinate and tape flowers |
| Brassicas | 1/2 mile (800m) | All brassicas cross with each other (cabbage × broccoli × kale × collards) |
| Beets/chard | 1/2 mile (800m) | Beets and chard are the same species — they will cross |
| Carrots | 1/4 mile (400m) | Also crosses with wild Queen Anne’s lace |
| Onions | 1/2 mile (800m) | Biennial — flowers second year |
| Peppers | 50-300 feet (15-90m) | Some crossing by insects; less than most cross-pollinators |
Alternative Isolation Methods
When distance is not possible:
- Timing isolation: plant variety A early and variety B late so they flower at different times
- Caging: build a mesh cage over plants during flowering. Introduce houseflies for pollination (for crops needing insect pollination)
- Hand pollination: manually transfer pollen with a brush, then tape flower closed. Labor-intensive but precise.
- Grow only one variety of each cross-pollinating species
Genetic Diversity
Minimum Population Sizes
Saving seed from too few plants causes inbreeding depression — loss of vigor, productivity, and disease resistance over generations.
| Crop Type | Minimum Plants for Seed | Ideal |
|---|---|---|
| Self-pollinating (tomato, bean, pea) | 6-12 | 20-50 |
| Cross-pollinating (corn, squash, brassica) | 25-50 | 80-200 |
| Corn (especially sensitive to inbreeding) | 100 minimum | 200+ |
For corn: never save seed from fewer than 100 plants. Corn is an outcrosser that suffers rapid inbreeding depression — within 3-4 generations of small-population saving, vigor drops dramatically.
Selection Strategy: Save from the Best, Eat the Rest
Each generation, select seed from plants that demonstrate:
- Disease resistance (survived while neighbors got sick)
- Drought tolerance (produced during dry spells)
- High yield
- Early maturity (important in short-season climates)
- Desired flavor, size, or color
But also save some seed from average plants — not just the best. Extreme selection narrows the gene pool. You want adaptation, not uniformity.
Landrace Development
Over 5-20 years of saving seed locally, your varieties will adapt to your specific soil, climate, pests, and diseases. This locally adapted population is called a landrace — and it is more valuable than any named commercial variety because it is optimized for your exact conditions.
Accelerate landrace development by:
- Growing multiple related varieties side-by-side (controlled crossing)
- Selecting survivors of disease or drought events
- Trading seed with neighboring communities (introduces new genetics)
Storage Conditions
The Rules of Seed Longevity
Dry + Cool = Long-lived seeds. Every 1% reduction in seed moisture doubles storage life. Every 10°F (5.5°C) reduction in storage temperature doubles storage life.
Target conditions:
- Moisture content: below 8% (seeds should snap when bent, not flex)
- Temperature: 40-50°F (root cellar) for multi-year storage
- Darkness: light degrades seed viability
- Low humidity: below 40% relative humidity
Drying Seeds
Spread seeds in a single layer on screens or paper in a warm, dry, well-ventilated area for 1-2 weeks. Turn daily. Seeds are dry enough when:
- Small seeds (lettuce, carrot): shatter when hit with a hammer
- Medium seeds (beans, corn): cannot be dented with a fingernail
- Large seeds (squash): snap cleanly when bent
Storage Containers
- Glass jars with tight-fitting lids: best. Mason jars, canning jars, repurposed food jars.
- Metal tins: good. Must be airtight.
- Paper envelopes inside a sealed container: good for organizing multiple varieties
- Plastic bags: acceptable short-term, not airtight enough for long-term
Desiccants
Add a desiccant packet to each storage container to absorb residual moisture:
- Silica gel: best. Salvage from packaging.
- Dry rice: 1 tablespoon per pint jar
- Powdered milk: 1 tablespoon wrapped in tissue
- Wood ash: very dry, absorbs moisture
Germination Testing
Test seed viability before planting season — discovering dead seed at planting time is catastrophic.
Protocol
- Count out 10 seeds (or 20 or 50 for more accuracy)
- Place on a damp paper towel or cloth
- Roll up, place in a plastic bag or covered container (not sealed — seeds need air)
- Keep at room temperature (65-75°F)
- Check daily. Count seeds that germinate.
- After the expected germination period (varies by crop — typically 5-14 days), calculate percentage.
Interpreting Results
- 90-100%: excellent. Plant at normal rate.
- 70-89%: good. Sow 20-30% more seed to compensate.
- 50-69%: marginal. Sow double. Prioritize growing a fresh seed crop this season.
- Below 50%: poor. Sow heavily, and definitely grow a replacement seed crop. This variety is one season from being lost.
Record Keeping
A seed bank without records is a box of mystery seeds. Maintain a seed catalog documenting:
- Variety name and description
- Source (where seed was originally obtained)
- Year harvested
- Quantity in storage
- Germination test date and result
- Growing notes: disease resistance observed, yield, flavor, maturity date
- Isolation method used (if cross-pollinating)
Use a bound notebook (not loose paper). Update annually. This record becomes increasingly valuable over years — it is the institutional memory of your food system.
Community Organization
Assign a seed steward — a person (or pair) responsible for:
- Maintaining the seed bank facility
- Conducting annual germination tests (January-February)
- Coordinating who grows which variety for seed (avoid everyone growing the same thing)
- Distributing planting seed each spring
- Collecting harvested seed each fall
- Maintaining records
- Trading with other communities for genetic diversity
The seed steward does not need to grow all the seeds personally — they manage the system and ensure nothing falls through the cracks. This role is as important as any other leadership position in the community.