Autoflower, feminised, regular & F1 hybrids – seed types explained

Before your first grow starts, there is a basic question: which seeds do you use? On packs you read “regular”, “feminised”, “autoflower” or “F1”. Here I explain what is behind these terms – and where the respective pros and cons for home growing lie.

Basics: cannabis is dioecious

Cannabis is normally dioecious: there are male and female plants. Similar to humans, sex is determined by sex chromosomes – female plants carry XX, male plants XY.^[1] The resin-rich glandular hairs (trichomes) in which cannabinoids and terpenes are made occur mainly on the female inflorescences.^[6] That is why most home growers are mainly interested in female plants. well established

Sex expression is not completely rigid, though: hormones play a role alongside genetics, and there can be plants that carry male and female flowers at the same time (hermaphrodites).^[2]

Regular seeds

Regular seeds are produced the classic way: a male plant pollinates a female one. On average, roughly half of the offspring are female (XX) and half male (XY).^[2] Anyone who mainly wants to harvest flowers therefore removes male plants before they release pollen – otherwise the female plants can be pollinated and form seeds.^[3]

Feminised seeds

The trick with feminised seeds: a female plant is induced to form male flowers itself. This is done with substances that inhibit the plant hormone ethylene – research describes silver thiosulfate (STS) in particular as especially effective, alongside e.g. colloidal silver.^[3] Because the pollen of these male flowers comes from an XX plant, the resulting seeds also carry XX – the offspring are genetically female.^[2][3] well established

Hempey’s tip

I only explain the principle here. There is deliberately no how-to for feminising on this site – and you don’t need one for your first grow.

Autoflower

“Normal” cannabis plants are short-day plants: long days promote growth, short days trigger flowering.^[7] Autoflower plants, by contrast, are day-length neutral: they start flowering without any change in the light period.^[4]

A 2024 study found that in the autoflower plants studied, a mutation in a “circadian clock” gene (CsPRR37) was the cause. Whether other genes play a role is something the researchers still want to clarify.^[4] preliminary Colloquially, autoflower genetics are often linked to “ruderalis” – a term that, however, is used inconsistently in botany.^[9]

F1 hybrids

“F1” comes from classical genetics and stands for the first filial generation from crossing two different parent lines. A nice example comes from a crossing experiment with cannabis: researchers crossed inbred plants that made only THC with plants that made only CBD. All F1 plants uniformly had a mixed THC–CBD profile. In the next generation (F2), however, the traits segregated again into three types.^[5] well established

Two things follow: an F1 is especially uniform mainly when the parents themselves are largely homozygous. And seeds from an F1 plant no longer give uniform offspring.^[5] In many crops, cross offspring also show the so-called heterosis effect (“hybrid vigour”): more biomass and faster development than either parent.^[10] I have not found any robust studies on how strong this effect is in cannabis F1 seeds. preliminary

Hempey’s fact check

“F1” on a pack is not a protected term. You cannot check from the outside whether truly homozygous parent lines were crossed. Genetic reviews such as Barcaccia et al. (2020, Frontiers in Plant Science) document that many commercial seed packs marketed as hybrids are heterozygous polyhybrids rather than true F1 crosses derived from homozygous inbred lines (IBLs).^[11]

Comparison for home growing

Seeds & the law in Germany

My experience

Flo’s Approach to Seed Types: S1 Preservation vs. Regular Breeding

In my garden, both feminised and regular seeds have their place depending on the goal:

• S1 feminisation for backing up keepers: When I find an exceptional female phenotype, I take cuttings, spray one cutting with colloidal silver and pollinate its sister cutting to store feminised S1 seeds in the fridge (see Breeding Guide).
• Regular seeds for true breeding: When creating and stabilising a genuinely new line across generations for structure and terpene profile (“Understand nature, then copy nature”), I always work with regular male (XY) and female (XX) plants.

Note: personal experiences are subjective and are not a recommendation.