Early signs of flowering generally begin to appear when day lengths shorten and approach 13 hours of daylight. Producers in Kentucky should start to watch for signs of flowering in late July to early August. Flowers continue forming into fall and most cultivars become mature and ready for harvest in September or October. Important exceptions to the above information are autoflowering cultivars. These cultivars are not photoperiod dependent, flowering more like a corn crop based on the time they have spent in the field. Autoflowering cultivars generally flower after three to five weeks in the field and are

Figure 3. Top: A hemp plant in early stages of flowering showing female preflowers (pistils) indicated by the yellow arrow. Bottom: A hemp plant in early stages of flowering showing male preflowers (immature pollen sacs) indicated by the red arrow. For cannabinoid crops male plants should be removed from the field before pollen sacs open and release pollen. (Photos by Jonathan Palmer (Top) and Craig Lee (Bottom). Photos edited by Shawn Lucas).

fully mature after seven to ten weeks. These cultivars tend to be smaller and are planted at different spacing (approximately 1 foot in row) than photoperiod sensitive cultivars.

As flowers mature, growers cull male plants if they are not growing from feminized seed or clones. A lack of male plants in the field should prevent pollination (note that other nearby Cannabis could pollinate a grower's crop) and female plants will devote resources to flower production rather than seed production. Culling males involves early identification of male flower structures and removing these plants from the field before pollen is released. Early male and female flowers can be seen in Figure 3. Scouting fields for males is time consuming and culling is laborious, so people often choose to grow "feminized" seed or female clones, however batches of "feminized" seed often produce some male plants and even female clones can produce male flowers under stress conditions. Producers should scout fields periodically for male flowers regardless of planting stock. It is important to scout fields as early in the flowering process as possible because male plants often develop flowers before female plants.

Cannabinoids increase in flowers as plants mature. After eight to twelve weeks of flowering (cultivars vary), female plants will be fully mature. However, well before full maturity, producers should begin monitoring their crop THC and CBD levels. Samples should be collected from the top five inches of flower from five to six different plants. These samples should be mixed together to form an averaged sample and then taken or sent to a lab that tests cannabinoid potency. Crops should be monitored closely as they approach the 0.3% THC legal threshold. In Kentucky, KDA requires two weeks notice of a producer's intent to harvest in order to conduct THC compliance testing. Producers may not harvest until compliance samples are collected and they should make decisions on when to notify KDA of intent harvest based on their own test results. The knowledge that cannabinoid levels will continue to rise between notifying KDA and the date upon which compliance samples are collected should inform that decision making process. Crops that test over 0.3% THC may have to be destroyed. Kentucky hemp growers should refer to the KDA hemp program for more information on compliance (https://www.kyagr.com/marketing/hemp-pilot.html).