Hemp is for the most part planted early in the year around March or May, for the Northern Hemisphere and September and November for the Southern Hemisphere. Thus, hemp is planted and grows during the spring, and after three to four months it becomes mature and is harvested.
If an early cropping is sought then the herb is then collected and dried towards the end of its flowering phase. That will have the effect of reducing the yield and number of seeds produced, but also increases the quality and durability of the hemp fiber, as well as the amount produced (the yield).
Again, remember that the THC levels in real industrial hemp are tiny.
As for more details about organic hemp cultivation. The seeds for the plant should be sown during a period that ranges from approximately mid-April to mid-May, at a depth of 1½ to 2½ inches (4 to 6 cm).
A significant advantage of growing this crop is that it requires much less fertilizer than other commercial crops, such as corn. Furthermore, usually no herbicides, fungicides or pesticides are required as this plant is normally not seriously affected by noxious weeds or bugs so measures to physically protect the plant are not necessary.
It is also necessary to note that there are numerous hemp varieties, with the European Union certifying as many as 46 varieties. Again, those strains contain extremely low levels of narcotic elements, with those types having a content of such chemicals as low as 0.2%, rendering the plant virtually useless for intoxication. These strains also have a very high percentage of fiber, with as much as a 40% of the plant being comprised of valuable fiber. Correspondingly, medicinal strains of Cannabis have a very low amounts of useful fiber and a much higher proportion of THC: from 2% to in excess of 20%.
The harvesting phase of hemp
Once the hemp is ready to harvest, these plants are cut at a height of ¾ to 1¼ inches (2 to 3 cm) above the ground. The stalks are then left out in the sun to dry, usually being left just by the stump of the plant. This drying time may sometimes require up to four days to complete.
Processing the hemp
Now that the cut stem is dry, it is ready to be processed to get the useful fiber out.
There are two ways to do this: the traditional way (which involves a process known as retting). Or the modern way (which involves the use of machinery to complete the separation of the fiber from the rest of the plant). This last mechanical process is thermomechanical pulping.
Retting is a rather straightforward process that involves the use of humidity and natural bacteria to destroy or separate the parts of the plant from the useful fibers. There are two variants of this process: Dew retting and Water retting and both can be used to separate the useful fiber from the rest of the tissues of the plant.
Water retting is by far the most popular and practiced method. It is simply submerging the cut and dried stalks in water for a period ranging from six up to fourteen days, depending on the judgment of the person who is doing it. The process works by letting water penetrate into the stem and expanding the vegetable cells inside. This swelling causes the outer part of the stem to burst and also increases the number of bacteria that eat the plant cells, but leave the valuable fiber.
Dew retting is another variant that is useful when the hydraulic resources have to be rationed, being very useful in drier climates and desserts where the farmer has to distribute the water carefully. In this process, the stalks are laid out in the field or open area and left there for a period of two or even three weeks. Within that period, the night dew creates an effect similar to the process explained above, but that effect is delayed and much slower. During the day, the sun dries the plants and during the night the process starts again. Eventually, weakening and destroying the plant tissues with the combined effect of the sun, the dew and the bacteria present within the stalks themselves.
It is especially useful and practical in desserts, where there is a considerable amount of dew in the nights and high temperatures during the day.
After the retting process is complete, the resulting fibers have to be cured, by leaving them on the open air until they are dry. Afterward, the useful fiber will be left but covered by the brittle leftovers of the plant tissues. That fragile tissue can be easily cracked and separated by bending the fibers either by hand or by passing it through rollers. After that, only the useful fiber will be left.
Thermomechanical pulping is the modern process and is, by far, much faster and easier.
In this process, the dried and cut stems of the hemp plant are further cut into smaller pieces and fed into the machine. Which crush and grind these pieces, creating heat as an effect of the physical force applied, and subsequently, vapor. Both the heat and the water vapor help soften and separate the vegetable tissues from the fiber, and is very efficient yielding more fiber and destroying or separating much of the plant tissues.
Other details of hemp farming
Other relevant details relative to growing this super plant are that it grows best at altitudes lower than 1300 feet (400 meters) above the sea level. Also, hemp is very resistant to lower temperatures and can withstand temperatures of less than 23°F (-5°C).
The water requirements are around 79 to 132 gallons (300 to up to 500 liters) per every 2.2 lbs (1 kilo) of dry stems. Please note that this amount of water is much less than the requirements of most other ordinary commercial crops, such as cotton. Which will require as much as 13 to 14 times the amount of water used for growing hemp.
Hemp is vulnerable to all sorts of noxious pathogens, such as bacteria, viruses, fungi and nematodes. Although, these conditions may result in a lower quality useful fiber, delayed growth and possibly even death of the plant. These diseases for the most part do not tend even to affect the overall yield of a field, so for this reason, chemicals are not always necessary. This extremely versatile plant is widely accepted to be a crop whose harvesting is friendly and beneficial to the environment. That is due to the lower amounts of pesticides, fertilizers and herbicides used during its growth and accumulation, especially when compared to other commercial crops such as wheat or corn.