IBL vs polyhybrid

IBL (inbred line) is the gold standard of cannabis stability. Created by selecting the most uniform offspring across multiple generations (F5, F6, F7+) and inbreeding within that population. Result: a highly homozygous line where every seed produces nearly identical plants.

True IBLs are rare. Most are landraces (which are heterozygous regional populations, but stable enough to be considered IBL-adjacent) or working lines that have been selected for 6+ generations under tight phenotype discipline.

Polyhybrid is the opposite. Cross two unstable lines (themselves hybrids of hybrids) and you get a polyhybrid — offspring with wildly mixed expression because the genetic deck was already shuffled in both parents.

Most modern commercial cannabis is polyhybrid. "Wedding Cake × GMO" is a polyhybrid because both parents are themselves complex multi-generation hybrids. The result: phenotype variation is the norm, not the exception.

Why this matters: a breeder selling F1 of two IBLs ships uniform packs. A breeder selling F1 polyhybrid is shipping a phenotype lottery. Both are legitimate; only one is uniform.

What "stable" actually means in practice

IBL = Inbred Line. Many breeders use F5 / F6 / F7 as the de facto stability marker, but the truth is more direction-specific. A line can be IBL-stable for terpene direction at F4 if the selection pressure was relentless, and unstable at F6 if selection was inconsistent.