Illinois is divided into three major geographic regions; the Gulf Coastal Plains, the Shawnee Hills, and the Central Plains. All three areas experience seasonal temperature variations, with the north being particularly prone to brutal and windy winters. But warmer weather during the annual growing season supports the cultivation of many a cold-intolerant crop, including industrial hemp.
Plant Hardiness Zone(s)
The state of Illinois is divided into five different zones, ranging from 5a to 7b, as per the USDA plant hardiness map. Hemp, which is a zone 8 to 11 hardy plant, would have a hard time surviving the state’s low winter temperatures if they were present year-round. Fortunately, the state warms up considerably in spring and summer months, providing the clement conditions hemp needs to survive and even thrive..
Hemp requires a minimum annual average temperature of 45 to 50 degrees Fahrenheit.
The state of Illinois has a varied climate, mostly due to its longitudinal orientation. In the north, the state exhibits a Humid Continental climate, while its southern regions are possessed of a Humid Subtropical climate. Although the north experiences winters ranging from cool to outright cold, the state’s southern expanses enjoy milder temperatures. The average annual temperature for the state as a whole is 51.3 degrees Fahrenheit.
Length of Growing Season
Hemp plants require 120 days to grow from seedling to maturity, at which time they are ready for harvest. The average length of the Illinois growing season is about 170 days, ample time for the crop to be seeded and live out its entire life cycle.
First frost hits like clockwork, usually within the first two weeks of October. Last frost can come as late as the end of April.. Older plants can usually tough it through their first frost exposure without significant loss of vitality, but it can kill young plants overnight.
Average Annual Sunlight
Hemp plants require a minimum of 12 hours of sunlight to grow to their maximum size during the vegetative stage; failure to which, the flowering stage is triggered.
Illinois receives on average 2,567 hours of sunlight each year.
Average Annual Precipitation
An average of 25 to 30 inches of rainfall annually is enough to support the growth of a healthy hemp crop, while oversaturation during extended periods of flooding can kill growing plants. With the months of May and June marking the wettest period of the year in the state, the average annual precipitation increases from around 32 inches in the north, to around 48 inches in the south. Flooding is also a common weather hazard in this part of the country.
Hemp plants should be grown at or below 600 to 800 feet above sea level.
The state of Illinois lies at an average height of 600 feet above sea level. The lowest point is at the Mississippi River, at 279 feet above sea level, while Charles Mound, standing at 1,235 feet above sea level is the highest point.
Hemp grows best in soils with a pH of 6 to 7.5.
Soil ph varies across the state from strongly acidic in parts of the southern region of the state, to slightly alkaline towards the north. Fertilizer will likely be required to adequately prepare the ground for planting.
Well-drained, aerated soils that retain moisture and nutrients well are best for growing hemp. Illinois is known for its wide variety of soils. However, most parts of the state have fertile but poorly to moderately-drained silt clay loam soils that are not ideal for planting, so careful consideration should be made before deciding where to lay down roots (literally).
Hemp’s arch-nemesis may be the European corn borer, but aphids, along with fungal, bacterial, and viral pathogens are all common threats to growing hemp plants in Illinois, as they are in most other states where hemp is cultivable.
Obtaining A Hemp Grower’s License In Illinois
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 Illinois, as well as a breakdown of the application process, click here.