Given the above data it can take anywhere between 10 weeks and 36 weeks for a plant to grow to maturity. That is, again, anywhere between 2.5 months to 9 months. The most common grow time is 3 to 4 months. All this is dependent on the strain that you choose. Pure Sativa can run anywhere into the 6 -9 month bracket. Indica can flower in 6 weeks. As you can image a Sativa/Indica plant will fall into the 2 -4 month flowering period.