Guide: How to grow hemp

Hemp (Cannabis sativa L.) is a strain of cannabis grown for industrial uses. In hemp, THC levels can’t surpass 0.2 or 0.3% (depending on the country); in strains grown for drugs, THC levels usually vary between 3% and 15%.

This is a crop with many advantages. There are many options for commercialization; it’s sustainable (it grows more vigorously than corn, but requires less water, agrochemicals, and fertilizer) and it’s low maintenance.

Let’s see how to grow hemp.

Choosing your goal

It’s estimated that there are 25000 products that can be derived from hemp. Among them are textiles, paper, construction materials, cosmetic products, medicinal products, animal feed, and fuel.

Hemp can be grown for its fiber (obtained from the stalk), for its seeds, or both. This decision is very important — it will greatly impact how you manage your hemp production.

Fiber

Hemp can produce long fibers and biomass. These can have a lot of uses — from textiles to construction materials. This type of hemp production is usually large scale and close to processing infrastructures.

Seed

Hemp seeds are highly nutritious, so they’re mostly used for food and oils. If you want to grow hemp to obtain seeds, you must consider that they’re fragile and should be handled with care, which means more costs for you.

Cannabinoid

The most popular types of hemp are the ones rich in cannabinoid. They contain high amounts of cannabidiol (CBD), which is famously used to make CBD oil and other medicinal products. Although growing these types of hemp, it’s not easy. You need to achieve high CBD levels while keeping THC levels under the legal limit.

Hemp cultivation is not legal everywhere. To be sure, look up the legal status in your own country. If you live in the USA, you can see here if it’s legal in your state.

Growing hemp

Agricultural cycle

Hemp is a Spring crop. Its cycle lasts about 120 days between April/May and August. Its active growth phase lasts about 6 weeks around the middle/end of July. Usually, it covers the soil in 3 weeks and after 80 days it reaches a height of around 5’10. The flowering period is long — from 3 weeks to a month.

If you want to harvest seeds: Favor the precocious varieties.

If you want to harvest fiber: Pick varieties with longer cycles.

Sowing

Do it between the end of April and the end of May, in a well-drained loam soil with a pH of 7.0 to 7.5 (though it can tolerate a pH of 6.0). Avoid compact soils. The seeding depth should not surpass 1 inch.

Sowing density varies — you can sow between 88 pounds and 155 pounds of seeds per hectare (2.5 acres). The decision you make in this regard must take into consideration the kind of operation you want to run.

If you want to harvest seeds: Go for less dense sowing, leaving more space between the plants to favor branch and flower growth.

If you want to harvest fiber: Allow less space between plants, in order to favor stalk development and discourage branching and flowering.

Irrigation

During its growth phase (6 weeks starting on the 20th day after sowing), hemp requires a lot of water — 12–15 inches. However, after this phase ends, it’s a drought-resistant crop.

Fertilization

Hemp reacts well to manure and other fertilizers. However, this crop’s yield is determined by its reaction to the photoperiod and the date of the sowing. Thus, it’s useless to give it too much nitrogen.

Harvest

Varies according to your goal.

If you want to harvest seeds: The harvest starts about 6 weeks after flowering or when the seeds are ripe. This is essential to guarantee that the percentage of oleic acid isn’t too high for commercialization. After being harvested, the seeds should be ventilated and dried up immediately. It takes 4–5 kg of seeds to produce 1 liter of hemp oil.

If you want to harvest fiber: Harvest should start right after flowering begins, when the fibers reach their maximum volume and quality. Make sure the stalks aren’t damaged. After the harvest, they should be retted, baled and stored.

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Sources: Sucessful Farming/ Cornell University/ Government of Alberta