A landrace is a crop population adapted to one locality by years of saving seed from the plants that survive and produce there, and it is built by growing a diverse mix of related varieties, letting them cross, and saving from the survivors season after season. Guidance in this series puts the time at roughly 5 to 20 years, so a landrace is a long-term investment that must be protected by good records and shared seed.
Part of Community Seed Bank Management
A landrace is a locally adapted, genetically variable population of a crop that is maintained by farmers without formal breeding.
A Landrace Is Variable On Purpose
A named commercial variety aims for sameness. A landrace holds many types: tall and short, early and late, different seed shades. Its strength is that some of these types do well in whatever the year brings. It is adapted to the soil, the cold or drought of the place, and the local pests and diseases, because over many seasons the plants that failed left less seed.
The speed is slow. The carrier gives 5 to 20 years of local seed saving; the Phase 2 selection guide says 5 to 10 (Seed Selection). Neither is a measured figure. How fast adaptation happens depends on the crop, how often it is grown and how strong the pressure is.
Method: Build The Starting Mix
Step 1: Pick the crop. Self-pollinating crops (bean, tomato, wheat, barley) are easiest to hold stable; cross-pollinating crops (corn, squash, brassicas) carry more variation and adapt faster but need larger populations (Genetic Diversity).
Step 2: Gather several related, open-pollinated varieties. Use varieties of one species that are known to do reasonably in your region, including seed from neighbouring communities. Avoid F1 hybrids (Open-Pollinated vs Hybrid).
Step 3: Grow them together. In a cross-pollinating crop, the varieties will cross and mix their genes. For a self-pollinating crop, mix the seed in equal parts, or make deliberate crosses by hand (Hand Pollination).
Step 4: Save from survivors. In each season, mark plants that did well in a hard year, mix their seed in equal parts and replant (Selecting for Adaptation vs Uniformity). Keep the population large enough to avoid inbreeding.
Step 5: Add new seed from outside every few generations. This keeps the gene pool wide.
Step 6: Hold a reserve. Store some seed of the early generations in the seed bank, so a failed year can be recovered.
Evolutionary Breeding Is An Old Idea
Plant breeders have long observed that a mix of varieties planted together year after year shifts toward types suited to the place. Harlan and Martini began a barley composite cross in the 1920s that was carried on for decades in California. The details of that work belong to a plant-breeding source; what matters here is the principle that natural selection by your own conditions does a great part of the work for free.
What Landraces Cost
- Time: results come slowly and cannot be hurried.
- Records: without notes on where seed came from and what was selected, the work cannot be repeated.
- Variable crops: harvest dates and sizes spread out, which suits a household and not a market.
- Isolation: other varieties of the same species must be kept away, or the landrace changes in ways you did not choose (Isolation & Cross-Pollination).
Common Mistakes
- Starting from a single variety. There is not enough variation to work with.
- Starting from F1 hybrids. The first generation after the hybrid is chaotic and takes extra generations to settle.
- Giving up in year three. Adaptation is slow; judge across at least five seasons.
- Losing the early seed. Always keep a reserve of the founder mix.
What’s Next
- Learn next: Grow-Out Trials and Variety Evaluation — testing what you have
- Combine with: Seed Inventory and Catalog System — recording the generations