Cannabis sativa Seeds | Hemp
LATIN NAME: Cannabis sativa
COMMON NAME: Hemp, Industrial Hemp, Sativa
Plant Profile
Industrial hemp is the fibre and grain form of Cannabis sativa, bred for a tall unbranched stem and a low resin content rather than for flowers. A fibre crop stands two to three metres at harvest, with a stem that is hollow and a bast layer that runs the full length of the internode.
The crop is grown on contract in France, China, Canada and Romania, on land that is rotated with cereals. It is an annual that goes in late and comes off late, which fits it into the gap between a spring cereal and a winter one, and that gap is the main reason farmers grow it.
Science & Biotechnology
The agronomy is built around density. Fibre crops are sown at twenty-five to forty-five kilograms per hectare in narrow rows, which suppresses branching and produces long unbranched stems; grain crops are sown at a tenth of that rate and branch freely to carry seed. The two cannot be grown from the same field in the same year.
Hemp takes up heavy metals from soil, particularly cadmium, lead and zinc, and it has been trialled on land contaminated by smelting and by the Chernobyl fallout. That is a genuine use in phytoremediation and a genuine reason to know where a fibre crop was grown before it goes into food or feed.
Uses & Benefits
The bast fibre goes into cordage, geotextiles, insulation and composite panels for the car industry, and the woody core, the hurd, goes into animal bedding, into hempcrete and into oil absorbents. Long fibre is a small and shrinking part of the market; short fibre and hurd are where the volume is.
The grain is sold as hulled hearts, as oil and as a protein powder, and the pressed cake is a feed for poultry and for dairy cattle. The crop is also grown for seed to be pressed for industrial oil, in paints and in cosmetics, a market that predates the food market by a century. Hurd is also used as a bulking agent in composting toilets and as a substrate for mushroom growing, both small but growing markets.
Growing from Seed
Sow from late April to early June, once the soil is above ten degrees, at two centimetres in rows fifteen centimetres apart for fibre. The seed germinates in four to seven days, and the canopy closes within five weeks, which is what suppresses weeds.
Harvest fibre at flowering, cutting the stem low and leaving it in the field to ret in the dew for two to three weeks, turning it once. For grain, wait until two thirds of the seed is ripe and combine at a slow drum speed, since the seed shatters. Check the licence and the permitted THC level before sowing anything.
Our Take
A contract crop for good land and a real option for contaminated land, but not a garden plant and not a crop to grow without a licence. Read the cultivar list first.
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