F1 hybrid
The first generation from crossing two stable parent lines. Uniform and often vigorous. Seed saved from it germinates fine, but the plants won't come true.
F1 means first filial generation: the plants you get from deliberately crossing two stable parent lines. The breeder keeps both parents going and repeats the same cross each season, which is why F1 seed costs more, and why every packet behaves the same way.
What F1 does and does not mean
It means uniform. The plants come up the same size, crop at the same time and carry whatever the breeder selected for, often vigour or disease resistance.
It does not mean genetically modified. It does not mean hotter, or better, or worse than an open-pollinated variety. And it does not mean sterile.
Saving seed from an F1
You can, and it germinates perfectly well. What comes up is the F2 generation, and that is where the parents' traits come apart again: different heights, heat levels, pod shapes and ripening times out of a single packet.
That is a nuisance if you wanted the variety you bought, and the start of something if you wanted to breed. Most named chilli varieties began as somebody's F2 selection, carried forward over several generations until it came true.
Naga Viper is the well-known cautionary example. Bred by Gerald Fowler in Cumbria, it briefly held the world record in 2011 at 1,382,118 SHU. Fowler describes it as a three-way hybrid, a parentage that has never been independently confirmed, and it is unstable enough that saved seed throws plants nothing like the parent.
To reproduce an F1 reliably, buy it again. To reproduce a variety from your own seed, start with an open-pollinated one.
