June 2019 marks the start of Arizona’s journey into the cultivation of industrial hemp. Cannabis Sativa is the cultivar defined as legal for the cultivation of industrial hemp. It generally prefers a mild, humid climate, with an average of 20 to 30 inches of annual rainfall. Despite this preference, the cultivar has proven to be remarkably adaptable, flourishing in extreme weather conditions all over the globe, from the deserts of Northern Mexico, to the frozen North of Russia.
Plant Hardiness Zones
Given the varied geography of Arizona, a mix of plateaus and mountainous areas, the USDA plant hardiness zones map for the state covers zones 5a to 10b. Since industrial hemp plants can only survive the minimal winter temperatures experienced in areas categorized under zones 8 to 11, growing it during winter is not possible in areas within the state categorized under anything lower than zone 8.
This is excellent news for Arizona farmers, giving hope that with a little planning and irrigation, cultivating Hemp on an industrial scale is definitely possible. Early planting is important, giving young plants the time needed to mature enough to withstand the hot summers. Hemp’s cold tolerance means seeds can be planted as soon as the ground is above freezing, meaning that the mild Arizona springs might be perfect for giving them a jump on the growing season.
Length of Growing Season
Industrial hemp has a relatively short growing season, going from seed to harvest in just under 4 months (about 110 days). In fact, during the vegetative growth stage the stalks can grow up to 6 inches per day – going from seedlings to over 12 ft tall. This should be an important factor for Arizonan farmers to keep in mind, allowing for the long summer days for increased height, and taking advantage of the short fall days for maximum fiber output.
Average Annual Sunlight
Day length plays an important role for hemp. In fact, it is considered a ‘short day plant’. What this means is that it only flowers when days are shorter than 12 hours – you might be wondering what that means for your fiber harvest. Well studies have shown that as the plant flowers, stalks slow their growth height wise, but the girth of the individual stalk increase substantial. Shorter days leading up to harvest can help increase your hemp fiber harvest significantly.
Average Annual Precipitation
In absence of precipitation, hemp grown in Arizona will require irrigation in order to thrive. That being said, the cultivar requires about 76% less water than cotton, and about 50% less than corn. This alone might motivate more farmers in Arizona to consider making the switch to growing industrial hemp.
Elevation is another important factor to consider, and can seriously impact the harvest of grain hemp by slowing seed development, and leading to a poor harvest. Hemp grown for seed should not be grown more than 600-800 feet above sea level, so any where considered the high desert should avoid cultivation of this crop. Elevation should also be considered when sourcing seeds, and seeds matured at higher altitudes might perform differently than expected.
Of course, with exponential growth, soil composition is key to maintaining the exponential growth seen during the growing season. Cannabis Sativa L. prefers sandy loam, with good drainage, and a neutral ph (about 7 – 7.5), it also consumes high levels of nitrogen. Soil should be supplemented in order to maintain ph level, and avoid yellowing and stalled growth.
Cannabis is for the most part pest resistant, and it’s rapid growth quickly stifles weeds that try to invade the fields. Once the seeds are established, weeding can be discontinued. Pests, such as the hemp flea, can be avoided by rotating fields, and avoiding planting hemp in the same field for more than two consecutive years.
Obtaining A Hemp Grower’s License In Arizona
Under federal law, it is illegal to grow hemp anywhere in the United States without first obtaining a grower’s license from the appropriate regulatory body for the state in which the interested party intends to plant the crop. For information on the legal status of hemp in Arizona, as well as a breakdown of the application process, click here.