Autoflowering and fast-flowering — why no dominant autoflower exists.

The question “is there a dominant autoflower” comes up often, and the short answer is no. But behind that no lies a logic that also explains what fast-flowering is and why it varies so much.

Why autoflowering cannot be dominant.

In nature dominant traits are, as a rule, well-functioning survival mechanisms, while recessive ones are more often “broken”. Autoflowering is a poor survival mechanism: in essence it is the plant’s inability to register the changing day–night cycle. A photoperiod plant waits for autumn and sets seed in time; an autoflower may sprout in early spring, and its second or third wave will not ripen before the frosts. Nature hedged by making the more viable photoperiod trait dominant.

What fast-flowering is.

Fast-flowering is a combination of the dominant photoperiod trait (“A”) and the recessive autoflowering one (“a”). Under complete dominance you get no fast type at all: “A” fully suppresses “a”. But find a phenotype with incomplete dominance and you have the various versions of fast-flowering plants.

Phenotypes by flowering trigger.

Phenotype 1 — light-sensitive fast: it requires a switch to 12/12, but the transition from veg to flower runs almost twice as quickly. Phenotype 2 — autoflowering fast with photo boost: it enters flowering by age (4.5–6 weeks) even under 18–20 hours of light, but quality and timing are noticeably better on 12/12.

Differences in morphology.

• Apical fast type: the main cola slows its growth and flowers abundantly while side branches develop more slowly — architecture reminiscent of autoflowers.
• Bushy variant: the top flowers quickly while the side branches keep vegetating for a long time; the top ripens noticeably earlier.

Ripening speed directly affects quality: fast phenotypes (7–8 weeks) produce less dense flowers and their leaves yellow earlier; normal and long ones (9–11 weeks) give the buds time to fill out, growing denser and oilier.