Knowing the sex of your marijuana plants is key to a successful and bountiful harvest. Male plants do not produce any buds and can easily cross-pollinate females, ruining the entire crop. Female marijuana plants produce large flowers that secrete resin that develops to round buds for smoking. Most consumer growers (and cannabis users) seek female plants. The earlier you identify and remove the male plants, the better. Missed male plants can pollinate and compromise the females because females need to produce THC and buds instead of expending energy trying to produce seed. Although female plants produce enough THC to be used as medicine, they won't create much when fertilized. As a result, your final crop will be smaller and less potent. Identifying young male plants earlier than 4 weeks after planting can be difficult. Female and male cannabis plants have unique pre-flower features best seen after 4-6 weeks. Male weed plants typically show their gender earlier than females, typically within 7-10 days indoors and roughly 3 weeks for outdoor plants.