Harvest. You will have to educate yourself to some degree on when to harvest your crop. Many common garden vegetables are harvested as they become ripe, and continue to produce throughout the growing season with proper care. Grains, on the other hand, are most often harvested when they are fully ripened and dry on the plant. Harvesting is a labor intensive operation, and as you become experienced in growing, you will find that you need to reduce the production of some plants so that harvesting can be managed.