Hawaii is the hardest state in the US to develop hemp, in a 0.3% max THC environment. That’s why it lost half of its R&D hemp crop one year. It was expected, even Colorado and Kentucky lose acres to noncompliant hemp. That only half was lost in Hawaii is a miracle. If they had stuck with the original plan, certified seed, it would likely be 100% lost. They are breeding a new variety of CBD hemp (“Type III“) suitable for the sub-tropics.
Low-THC hemp is a temperate crop and traditionally didn’t grow south of 35° (that was >0.3% THC marijuana instead).
PHOTOPERIOD CANNABIS MORPHS EASILY
It’s a botanical fact about photoperiod Cannabis, woefully misunderstood. Low-THC hemp traditionally was found north of around 35° latitude (northern hemisphere, same principle in the south), and it would morph into higher-THC marijuana (“not-hemp”) when moved south. It’s not that no Cannabis can grow there, just that historically it wasn’t low-THC Cannabis (hemp) growing to the south. Even feral hemp (ditchweed) in the midwest can be 1-3% THC.
Look at the hemp producing powerhouses, they’re all temperate: Canada, France, Germany, Estonia, Russia. Look at the traditional outdoor marijuana producers, all are sub- and tropical: Jamaica, Mexico, Hawaii, Colombia, Thailand. England was never known for its weed and Jamaica was never known for its low-THC hemp.
COMPLIANCE IS CRITICAL
Keeping the hemp crop compliant (under 0.3% delta-9 THC in the flowers) is a huge deal, the difference between success and financial ruin. In the worst case federal or state criminal and civil prosecution under RICO felony laws and asset forfeiture. The minimum mandatory sentence for growing over 1,000 plants (easy in even just one acre) is 10 years. Some states such as California could assess $10,000 per day fines for “growing marijuana without a license,” as noncompliant is legally considered marijuana, a Schedule 1 controlled substance in the state and federally. And any federal USDA or water programs you are in may be jeopardized for “growing marijuana not hemp.” All it takes is one local Sheriff up for re-election and wanting to make the headlines.
CERTIFIED HEMP CULTIVARS
Additionally, certified hemp cultivars are bred for the latitudes 40 to 65. But moving a cultivar even one degree south changes it from how it was certified to perform. Thus one for say 45° latitude will fail at 20°. Growing for seed is the hardest, it requires light supplementation.
TROPICAL SUMMER: SHORT DAYS
The closer to the equator, the shorter the days. That’s why you have to supplement light until you’re ready to flower at the Equator. It’s 12-13 hours all year, and photoperiod Cannabis flowers as it approaches 12 hours of darkness. But when it’s almost 12 hours all year, she gets confused.
In this map from Cannabis: Evolution and Ethnobotany (Clarke/Merlin 2013), note the lack of hemp in equatorial zones, they are all drug varieties. Chinensis in southern China is the only outlier, like it is in so many other ways. But it’s still not equatorial. (D= drug Cannabis, H= hemp)
BREED A SOLUTION
It’s not that this obstacle can’t be overcome, but first you have to know it’s something to be overcome. Especially for seed, it’s an issue more than fiber which can be unflowered for many applications. There’s a breeding solution, but just throwing Euro or Canadian hemp seed in the ground in say Colombia, it will fail. One needs a late-flowering genetic in the tropics, and all the certified hemp is early-flowering. An autoflower (day neutral) variety has a better chance of succeeding. If all you want is fiber in lower latitudes, consider growing Kenaf instead. It is like fiber hemp in so many ways, and likes the south.