How many hours of light does it take to grow marijuana?

If you grow marijuana indoor from a random seed, unless you have a seed that auto-flowering, you need to understand the grow stages of marijuana and how they are affected by the light cycle.

Cannabis plants have two major growth stages:

1.) Vegetative – seedlings or clones enter the vegetative period

Provide 18-24 hours of light every day (indoor)

Marijuana has only grow long stems and leaves

2.) flowering (budding) stage leads to harvest

At least 12 hours of uninterrupted darkness every day (short days)

Marijuana begins to blossom / sprout

The first stage

Most indoor growers provide 18-24 hours of light to cannabis plants every day during plant growth. The exact number of hours required to keep a plant in the vegetative period depends on the strain, but more than 18 hours a day will basically keep all cannabis plants in the vegetative period

The second stage

Cannabis Plants will not stay in the vegetative period until they have 12 hours of complete and uninterrupted darkness. They begin to bloom when they are exposed to darkness for 12 hours or more a day.

When marijuana is grown indoors during the flowering period, once the cannabis plant reaches the required size during the vegetative growth period, growers usually place the plant on a schedule of 12 hours of light and 12 hours of darkness (12 / 12). On average, growers grow indoor plants under 18 / 6 or 24 / 0 light for 4-8 weeks.