The hop plant is a long fast-growing vine. It dies back or is harvested at the root in late autumn and regrows to 25 feet or more the following summer. The part of the plant of interest to brewers and beer lovers is the cone, the flower from the female hop plant
A hop plant is either male or female. That is easy for us humans to understand but apparently it is less common in the plant world. Both male and female hop plants produce cones but the male cones are of no importance in brewing beer, or in any other application. So much so that male hops are virtually eradicated in commercial hop nurseries. Talk about gender discrimination!
Hops are most commonly propagated from rhizomes cut from the roots of healthy, older plants. This produces clones that ensure that the resulting plants are also female. The vine produces small blooms that mature into strobiles, the familiar green cones. These mature in early autumn when they are harvested.
Harvesting is done by cutting the entire vine at the root, picking the cones then drying them in a kiln. They are then pressed and packaged.
Even dried, hops' greatest enemy is time. Under the best conditions - dry and cool - hops cannot be kept longer than just a couple of years.