Fiber-producing plants should always have plenty of proper nutrients, especially nitrogen, which is the most important element needed. Irrigation is seldom practiced. Harvesting Hemp is ready for harvest four to five months after planting, rarely earlier for some varieties. Harvesting depends on the climatic conditions, the variety of hemp grown and whether the crop is being grown for hemp or seed. In temperate areas, hemp is usually harvested from mid July to mid August.
Male plants are ready to harvest for fiber when the leaves change from dark green to light brown.
Hemp is harvested when the staminate flowers are beginning to open and shed their pollen. Seed is harvested from the female plants when most of it falls off when the plant is shaken. Best time of day to harvest seed is in early morning when fruits are turgid and conditions damp. As fruits dry out by mid-day, seed loss increases due to shattering. Usually stems are cut and the seeds shaken out over canvas sheets or beaten with sticks to extract the seeds.