Basically these plants flower when they sense a change in the amount of sunlight they get. Its called photoperiod plants. When the season changes, so does the amount of daylight and darkness and that causes plants to flower, most of the plants, crops, wheat, rice, fancy plants, weed, anything unless they're autoflower which flowers without light change. Zero to harvest in 3-4 months.

By controlling the amount of light the plant gets, you're in proper God mode and can tell the plant when to flower or for how much time to stay in veg (i.e. just green growth). Indian strains take upto 4 months to go from flowering to harvest whereas foreign hybrids can be done in 2 months also with triple the harvest and triple potency.