04/27/2022
Ripeness
A plant’s flowering cycle, and its ripening and harvesting time, are variety specific. Each variety is programmed to respond to a critical period of darkness that turns growth from vegetative to flowering. Indoors, this is accomplished when the lights are cut back to 12 hours. Outdoors, the critical dark period usually varies between 9 and 11 hours of darkness. In addition to genetics, flowering time is also affected by light intensity and total light received on a daily basis (DLI), ambient temperature, and nutrients.
The best way to determine the picking time is by watching the development of the trichomes (the stalk-like resin glands that contain the active compounds), which grow on the leaves surrounding the flowers. The flower area becomes covered with these resin glands over time. Tools are available that can measure cannabinoid content in flowers and monitor for its peak when choosing a harvest date. Growers can also use magnification to assess the size, color, and clarity of the trichomes. Combined with lab testing at various points of maturation, visual cues can be used during future harvest rounds to estimate when peak potency has been achieved for each cultivar.
Late-season and long-maturing varieties usually spend about three to five weeks in this period of heavy trichome growth.
As flowers near ripeness, their caps swell with resin and the trichomes become more prominent and stand erect. The viscous, sticky liquid that accumulates contains terpenes and cannabinoids, which are produced on the inside membrane of the trichome cap. As the resin accumulates in the cap, the flower odor becomes more intense.
Excerpt from the Cannabis Grower's Handbook
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