# Heirloom

> An heirloom is a seed line kept and passed down by growers for decades, usually outside its region of origin, preserving an older type rather than a recent hybrid.

- Canonical: https://genetixbay.com/knowledge/glossary/heirloom.html
- Also written: heirloom line, heirloom seed, heritage line, heritage seed, heirloom strain
- Glossary category: Genetics and breeding · Evidence: Grower practice
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

An heirloom (or heritage line) is a seed line that has been maintained and passed on by growers over many generations, typically decades, without being crossed into new [hybrids](https://genetixbay.com/knowledge/glossary/hybrid.md). In cannabis it usually means [landrace](https://genetixbay.com/knowledge/glossary/landrace.md) or early-hybrid material that left its source region, often in the 1960s to 1980s, and has been kept going by successive growers since.

## In practice

Heirlooms are a key reservoir of older genetics. Seed stock of 50 to 70 years old, kept and regrown carefully, can still test in the high 20s for [total cannabinoids](https://genetixbay.com/knowledge/glossary/total-cannabinoids.md), which is direct evidence that the genetics were never weak.

Keeping an heirloom honest means [open pollination](https://genetixbay.com/knowledge/glossary/open-pollinated.md) with enough plants each generation, isolation from other pollen, and records of who kept it and when. Seed from a handful of parents each time narrows the line through [genetic drift](https://genetixbay.com/knowledge/glossary/genetic-drift.md); crossing it to a modern hybrid ends it as an heirloom, whatever the label says.

## Don't confuse with

- **Landrace**: maintained in its region of origin by local farmers; an heirloom may descend from one.
- **Clone-only**: a single [genotype](https://genetixbay.com/knowledge/glossary/genotype.md) kept by cuttings; an heirloom is a seed population.
- **"Classic" or "OG" (marketing)**: often hybrids under an old name.

## Related terms

[Landrace](https://genetixbay.com/knowledge/glossary/landrace.md), [Open-pollinated](https://genetixbay.com/knowledge/glossary/open-pollinated.md), [Accession](https://genetixbay.com/knowledge/glossary/accession.md), [Gene pool](https://genetixbay.com/knowledge/glossary/gene-pool.md), [Seed run](https://genetixbay.com/knowledge/glossary/seed-run.md)

## Read more

- [Polyhybrids vs landraces: what each gives a breeder](https://genetixbay.com/knowledge/breeding/polyhybrids-vs-landraces.md)
- [Landraces of the world: an overview](https://genetixbay.com/knowledge/genetics-history/landraces-of-the-world.md)

## Sources

1. Villa TCC, Maxted N, Scholten M, Ford-Lloyd B. 2005. Defining and identifying crop landraces. Plant Genetic Resources 3(3):373-384. https://doi.org/10.1079/PGR200591