Photoperiod cannabis flowers in response to light cycle changes — specifically, when the dark period extends past roughly 12 hours per night. Indoor growers force flowering by flipping their lights to 12/12; outdoor growers wait for the natural shorter days of late summer / early fall.

Autoflowers (auto-flowering) inherit a different flowering mechanism from ruderalis — a hardy, low-THC variety from northern latitudes that evolved to flower on a fixed age timeline because the growing seasons up there are too short to wait for shifting light. An autoflower starts flowering ~3-5 weeks after germination regardless of light.

Practical differences: autos go from seed to harvest in 8-12 weeks total. Photoperiods take 12-22 weeks depending on flowering strain. Autos can't be cloned reliably (clones inherit the mother's age and flower immediately). Photoperiods can be kept in veg indefinitely and cloned freely.

Yield, potency, and terpene depth historically favored photoperiods, but modern autoflower genetics (Mephisto, Night Owl, Sweet Seeds, Dutch Passion auto lines) have closed that gap significantly. Autos remain a different tool, not an inferior one.

Can I clone an autoflower?+
Technically yes, but the clone inherits the mother's age and will flower immediately — making clones unproductive.
Are autos less potent?+
Modern auto genetics are competitive. The early '00s gap has mostly closed.