IBL (Inbred Line)
Definition: An IBL, short for inbred line, is a cannabis strain that has been bred within itself for many generations, typically six or more, while selecting for the same traits each time. The result is a stable, true-breeding population whose seeds grow into plants that closely resemble each other and their parents.
How IBL (Inbred Line) works
Making an IBL starts with a cross or a population, then repeats a simple loop: grow out many plants, keep the ones that match the target, breed those together, and repeat. Each round increases homozygosity, the share of genes carried in matching pairs. By the sixth or seventh filial generation, unwanted variation has mostly been bred out.
What growers gain
- Predictability: plants from one pack finish at similar heights and times, which makes canopy management and sea of green setups easier.
- Seed saving: crossing two plants from an IBL gives seeds that grow much like the parents, unlike an F1.
- Breeding value: crossing two different IBLs produces the most uniform F1 hybrids.
Trade-offs
Inbreeding can expose weak recessive traits, such as reduced vigor, poor root growth or a tendency toward hermaphroditism, if breeders do not select carefully and keep population sizes large enough. Good IBLs are worked with dozens or hundreds of plants per generation for that reason.
Many famous landrace-derived strains are maintained as IBLs. When a breeder describes a strain as stable or true-breeding, they are claiming IBL-level consistency.