I wouldn't flower anything under a foot, but that's just me.

The plant produces a hormone (phytochrome) beginning at germination. When this chemical builds up to a critical level, the plant changes its mode from vegetative growth to flowering. This chemical is destroyed in the presence of even a few moments of light. During the late spring and early summer there are many more hours of light than darkness and the hormone does not build up to a critical level. However, as the days grow shorter and there are longer periods of uninterrupted darkness, the hormone builds to a critical level. Flowering occurs at different times with different varieties as a result of the adaption of the varieties to the environment.

The potency of the plant is related to its maturity rather than Chronological age. Genetically identical 3 month and 6 month-old plants which have mature flowers have the same potency. Starting from seed, a six month old plant flowers slightly faster and fills out more than a 3 month old plant.

Basically, I would say anything over 10 inche is up to you. :thumbsup: