In the Northeast, hemp harvest can take place any time from late August through October or later depending on hemp varieties and weather conditions. Harvest for autoflowering varieties can somewhat reliably be determined with the use of recommended harvest dates for individual varieties whereas full term or photoperiod sensitive varieties more often require careful monitoring through the use of visual or aromatic cues. Primarily harvest date for flower crops is determined by a number of noticeable changes in the physical characteristics of trichomes, bracts, and pistils. The trichomes, known as capitate-stalked resin glands, will begin to form as stalked structures capped with a bulbous head (similar to a small mushroom) on flower surfaces. Depending on growth operation, these glands will also begin to turn opaque and eventually amber before degradation. Other flower components such as the bracts of each individual flower will begin to swell, similar to as if flowers were pollenated, and pistils of each flower will begin to turn brown. Once approximately 90% of those pistils have begun browning, in conjunction with these other visual cues, we generally begin to harvest plants.
Vermont, University of Vermont, hemp flower, CBD
Darby, Heather and Bruce, John, "Hemp Flower Harvest Date" (2020). Northwest Crops & Soils Program. 418.