F1, F2, and F3 refer to “filial generations,” which describe how many breeding generations a seed line has gone through.
- F1 (First Filial):
The first generation created by crossing two parent plants. F1 seeds tend to be uniform and vigorous.
- F2 (Second Filial):
Produced by crossing two F1 plants. This generation shows more genetic variation, making it popular for pheno hunting.
- F3 (Third Filial):
Created by crossing selected F2 plants. F3 seeds begin to show more consistency as desirable traits are refined.
In short:
F1 = uniform
F2 = variation
F3 = refinement
Note:
If a seed listing does not specify a filial generation, it is typically an F1 polyhybrid—a first-generation cross made from parents that may already contain multiple genetic lines.