# Selfing

> Selfing is pollinating a plant with its own pollen, in cannabis usually by reversing part of a female to make pollen; it is the most intense form of inbreeding.

- Canonical: https://genetixbay.com/knowledge/glossary/selfing.html
- Also written: self-pollination, self pollination, selfed, self-fertilisation, self-fertilization, autogamy
- Glossary category: Genetics and breeding · Evidence: Established
- 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"

Selfing is fertilising a plant with its own pollen. Cannabis is dioecious, so a female does not normally make pollen; breeders induce it by treating a branch or a clone of the same female with [silver thiosulfate](https://genetixbay.com/knowledge/glossary/sts.md) ([sex reversal](https://genetixbay.com/knowledge/glossary/sex-reversal.md)). The seed is called [S1](https://genetixbay.com/knowledge/glossary/s1.md).

## In practice

Selfing halves [heterozygosity](https://genetixbay.com/knowledge/glossary/heterozygous.md) in one generation (F = 0.5), so it brings out hidden [recessives](https://genetixbay.com/knowledge/glossary/recessive.md) quickly and can show what a clone carries. It is a fast diagnostic and a last-resort way to keep something of a clone in seed form.

It is also one of the main routes to [herm-prone](https://genetixbay.com/knowledge/glossary/herm-prone.md) lines. Selfing a plant that has already shown [intersex](https://genetixbay.com/knowledge/glossary/hermaphrodite.md) flowers, stacking S1 on S1, or releasing selfed seed without growing it out and culling, all spread instability.

## Don't confuse with

- **S1**: the seed produced by selfing.
- **Feminised seed**: any seed made with reversed female pollen; selfed seed is [feminised](https://genetixbay.com/knowledge/glossary/feminised-seed.md), but feminised seed is often a cross between two different females.
- **Hermaphrodite pollination**: accidental selfing by a herm in the room, which also selects for the herm trait.

## Myth check

House position: selfing is mostly frowned upon on GenetixBay. Historically it was an emergency measure to save a line, not a breeding method. Real breeding uses real, selected males, and males are encouraged and rewarded here. Only ever self a proven-stable female, then cull every intersex offspring. See [S1s and selfing](https://genetixbay.com/knowledge/breeding/s1-selfing.md).

## Related terms

[S1](https://genetixbay.com/knowledge/glossary/s1.md), [Sex reversal](https://genetixbay.com/knowledge/glossary/sex-reversal.md), [Feminised seed](https://genetixbay.com/knowledge/glossary/feminised-seed.md), [Inbreeding depression](https://genetixbay.com/knowledge/glossary/inbreeding-depression.md), [Homozygous](https://genetixbay.com/knowledge/glossary/homozygous.md)

## Read more

- [S1s and selfing: what happens when a plant pollinates itself](https://genetixbay.com/knowledge/breeding/s1-selfing.md)

## Sources

1. Punja ZK, Holmes JE. 2020. Hermaphroditism in marijuana (Cannabis sativa L.) inflorescences: impact on floral morphology, seed formation, progeny sex ratios, and genetic variation. Frontiers in Plant Science 11:718. https://doi.org/10.3389/fpls.2020.00718
2. Flajšman M, Slapnik M, Murovec J. 2021. Production of feminized seeds of high CBD Cannabis sativa L. by manipulation of sex expression and its application to breeding. Frontiers in Plant Science 12:718092. https://doi.org/10.3389/fpls.2021.718092
3. Charlesworth D, Willis JH. 2009. The genetics of inbreeding depression. Nature Reviews Genetics 10:783-796. https://doi.org/10.1038/nrg2664