Grow Your Own: The Basics of Industrial Hemp from Seed to Stalk
For generations, industrial hemp was considered a “lost art.” As this billion-dollar industry makes a roaring comeback in South Dakota, growers and hobby farmers are seeking honest, field-tested information.
Here at Dakota Hemp, we want to educate producers on how to cultivate a bumper crop of hemp for biomaterials or grain. Using our popular Hemp Education series as a guide, we’re simplifying everything you need to know about planting, growing for grain vs. stalk, and managing this versatile pioneer crop.
1. Planting Hemp Seed: Start with a Good Foundation
A successful hemp crop starts weeks before the seed even breaks through the soil. In our area of South Dakota, the ideal “planting window” opens in early May when soil temperatures reach 50 degrees F on an annual basis.
Planting Tips:
- Avoid digging down for moisture. Hemp seeds have thin skins that can’t handle stress. Stick with 1/2 inch to 1 inch of depth when planting.
- Make sure the seed has good seed-to-soil contact. Rolling your field after planting helps ensure the seed bed is tight and every plant will pop up evenly across the acre.
Planting Equipment:
Set your planter to a grain drill (air drill works great too!) at the sorghum setting. Keep rows narrow; no wider than 15 inches. Weed suppression comes from the hemp crop’s ability to “canopy” out weaker weeds.
2. Growing Hemp Grain (Seeds)
Growing hemp strictly for grain requires slightly different management techniques than stalk growth.
- Planting Density: 30 lbs per acre is ideal if you plan to harvest the seed. You want everything to reach maturity at the same time for mechanical harvest.
- Nutrients: Keep NPK in similar ratios. For grain-focused plants, we suggest a fertilizer program of roughly 120/30/20.
- Harvest Timing: Grain harvesting requires a flick of the wrist. Grab a seed head and clap your hands together. When about 40 percent of the seeds fall out, it’s time to harvest!
- Post-Harvest: Hemp grain should be dried down to around 20-25% moisture content. Put your crop on air as soon as possible to avoid damaging the precious protein and omega fats inside the seed.
3. Growing Hemp Stalks (for Fiber)
The race to thirty feet! As you may have guessed, growing hemp for fiber is all about plant height and biomass. This is the primary source for high-quality hemp hurd and industrial fiber.
- Planting Density: We like to shoot for about 22 lbs per acre when growing for hurd or fiber.
- Days to Harvest: Speaking of race to thirty feet—hemp plants grown for fiber typically reach heights of 8-12 feet per week until sunlight decreases in late summer. This growth really picks up after the 60-day mark!
- Monitoring Stalk Development: Grab a stalk and cut it into 18-inch pieces. Examine the inside of the plant for “hurd.” As hemp gets closer to maturity, the inside of the stalk is no longer hollow and will add significantly to your tonnage.
- “Retting” Hemp in the Field: Once you cut your stalks, let them sit in the field for about two weeks. “Retting” is a process that relies on naturally occurring bacteria and moisture to break down the ties that bind fibers to the core of the plant.
Still Have Questions? Our Hemp FAQ Has Answers
Q: Can I spray Round-Up or some other herbicide to control weeds? A: With hemp production in South Dakota, there is currently one main herbicide approved for use called Sonalan. As long as you apply it before planting, hemp grows so quickly that a canopy is naturally established to out-compete weeds after the first few weeks of growth.
Q: What’s the best way to harvest hemp without destroying my tractor tires? A: Cut your stalks with either a sickle bar or swather and let them sit. Stalks should be left in the field for about two weeks to properly ret. Don’t grind your stalks down too close to the ground; leave about 6 inches of “stubble.” Your tires will thank you! You can read more about our harvesting methods here.
Q: How dry does hemp grain need to be before storage? A: Dry your hemp grain down to 10% moisture before placing in storage. Grain stored at higher moisture levels is prone to mold growth.
About Dakota Hemp’s Mission for Hemp Education
Whether you are new to hemp cultivation or an experienced farmer wanting to diversify your operations, we hope our Hemp Education series helps lower your risk and increase your yield.
At Dakota Hemp, we’re growing hemp not just for profit, but to help revitalize the American farm with a carbon-negative crop.