F2 (filial 2) is created by either self-pollinating an F1 plant or crossing two F1 siblings. Where F1 is uniform, F2 is wildly variable — the genetic deck is reshuffled and recessive traits suddenly appear.

This is the breeder's playground. F2 populations are where you find unusual phenotypes — the candy-flavored cut, the purple-expressing keeper, the sativa-leaning outlier in an indica line.

F2 packs are not for growers who want consistency. They're for hunters: people willing to pop 20+ seeds, grow them out, and select the standouts for further work.

F3, F4, F5 and so on continue the inbreeding — each generation increasingly homozygous and stable. An IBL (inbred line) is typically considered stable around F5–F7.

Why is F2 so variable?+
Mendel's segregation in action: F1 hides recessive traits as heterozygous; F2 lets them re-pair and express.
When does a line become 'stable'?+
Most breeders consider F5–F7 stable enough to call IBL, depending on how aggressively they selected each generation.