This should be the first question every Hemp farm asks. Hemp is an Obligate short day plant, meaning the plant requires daylengths shorter than a certain critical length, in order to trigger its flowering cycle. Daylength is vastly different across the various growing regions were hemp is cultivated and the critical time period is different for the many different strains of hemp.
Because most farmers face the risk of frost and bad weather near the end of the growing season and the fact that most hemp strains increase their % of THC the longer they grow in their flower cycle, its paramount for farmers to determine when they want to harvest, and then determine what the daylength is in their region 7-8 weeks prior to this harvest date.
That information will allow them to then decide on the best genetic hemp strain to plant and grow, ensuring the plant will have the best possible outcome in yield, while remaining compliant to regulations
The reason this question is so important is to help determine when a farmer should plant their hemp and how many plants per acre.
Because Hemp is an obligate short day plant, it has two distinct growing cycles. The vegetative growing cycle and the flowering cycle. During the flower cycle the plant puts off its flower buds (colas) and produces the sticky resin where the CBD lies. But during the vegetative cycle, the plant is solely focused on creating more plant matter for itself, so the longer the vegetative cycle, the bigger the plant will grow.
If you plan to harvest by machine, then you need to pick a hemp cultivar that will stay under 4’ or so at the time of harvest and this means planting more plants per acre. You can achieve this by picking a cultivar that has a relatively high critical daylength to trigger its flowering cycle, 14- and 1/2-hour days for example, to limit the number of vegetative weeks the plant will grow, and targeting an earlier harvest time (early September for example)
If you plant to harvest by hand, then maybe you want as big a plant as possible, so you can capture as much lbs. per plant as possible. In this scenario, you would pick a hemp cultivar that has a lower critical daylength requirement – 13 hours of daylength to trigger. This would ensure you get the maximum number of vegetative weeks as possible, for the plant to grow extremely large before it changes to its flower cycle. This will also mean the harvest period will be later: Mid October, so be sure your weather in your growing region is still acceptable temperatures at this time of year, if you choose to go this route.
With all this discussion about hemp being an obligate short day plant, it is important to know the daylengths of your growing area during the planting season (usually May & June) so you know what hemp cultivars can be planted and when. Planting too early, could trigger the flower cycle of the plant pre-maturely resulting in 6” tall plants with flower buds.
What is the daylength in your region during the time hemp triggers into its flowering cycle (usually late July and August). Planting a cultivar that triggers too late for your region and you could end up with 10’ tall trees and no flower bud, by the time your first frost hits!
A very user friendly website: https://www.timeanddate.com/sun/ can help you determine your areas daylength at any time during the year.
Clones are far superior to seed material for a number of reasons. The first being that clones are all genetically the same. They come from the exact same mother stock plant and therefor all grow the exact same and time out the exact same
Seed material has multiple phenotypes across the same cultivar. Think of it like siblings from the same parents. One of the kids has green eyes, the other brown eyes. One child grows to be 6’ 3” tall the other grows to 5’ 11”. Same goes for seedlings. The plants will grow differently and time out differently in their flowering cycle. So while 1/3 of your field is ready for harvest, the other 1/3 needs 2 more weeks to optimize its flower cycle and the final 1/3 needs another month. Once you harvest all this plant material together your CBD % that once was 12% on the flowers that were fully ready at time of harvest, the amalgamated bio-mass is now 7% CBD because of the plant material that was immature at harvest.
The next reason clones are superior is that there is no risk of any plant pollinating the other from hermaphrodite. Since all plants are genetically identical, a good clone producer would have ensure his mother stock never had this hermaphrodite gene
Feminized Seedlings on the other hand are bred with hermaphrodite plants – purposely. So the Hermi gene is introduced and a % of all the seeds bred this way will turn out to be hermaphrodites. These plants will put off pollen sacks and pollinate, or seed out, all the plants in the surrounding area. If you plant 100,000 seedlings, even if only 3% of them hermaphrodite out, it potentially could seed out all 100,000 plants, as that 3% of the population will be spread throughout your field, because you cant tell a hermi plant from a regular one until its too late.
Are you planning to sell smokable flower bud that is manicured and pretty? This means hand harvesting and hang drying your hemp. Do you have the labor, and space to accommodate this?
Are you planning for bio-mass that you will sell to an extractor? If so, will the extractor take combine harvested material, or do you need to use more gentler methods, such as a Shelbourne harvester? Will the extractor take the hemp wet, right out of the field? Or will you need to dry it all first? Field dry or run through machine driers?
Maybe you plan on extracting yourself. Full spectrum distillate? T-Free distillate? Isolate?
It is important to have a sales plan in place before one hemp plant is planted in the ground, so you can plan properly for harvest that inevitable comes.