Hemp Factsheet
 1. Plant Description
Hemp (Cannabis sativa L.) is an annual herbaceous plant with a slender
stem, ranging in height from 4 to 15 feet and a diameter from 1/4" to
3/4". The innermost layer is the pith, surrounded by woody material
known as hurds. Outside of this layer is the growing tissue which develops
into hurds on the inside and into the bast fibers on the outside. The stem
is more or less branched, depending on the crop density. When sown thickly
the stems do not branch. The leaves are of a palmate type and each leaf
has 7 to 11 leaflets, with serrated edges. The strong tap-root penetrates
deep into the soil. However, if the soil conditions are unfavorable, the
main root remains short, while lateral roots become more developed.
2. Soil and Soil Preparation
Soils
Industrial hemp can be grown on a wide variety of soil types. Hemp prefers
a sufficiently deep, well-aerated soil with a pH pf 6 or greater, along
with good moisture and nutrient holding capacity. Poorly drained soils,
however, are not recommended as excess water after heavy rains can result
in damage to the hemp crop. Hemp is extremely sensitive to flooding and
soil compaction
Soil Preparation
A fine, firm seedbed is required for fast, uniform germination of hemp
seed. Conventional seedbed preparation and drilling are probably ideal.
The seedlings will not emerge uniformly if the seed is placed to a depth
greater than 2 inches. "No-till systems" can also be used with
good results, but may be more vulnerable to erratic emergence depending
on the growing season.
3. Nutrition
To achieve an optimum hempyield, twice as much nutrient must be available
to the crop as will finally be removed from the soil at harvest. A hemp
field produces a very large bulk of vegetative material in a short vegetative
period. The nitrogen uptake is most intensive the first 6 to 8 weeks, while
potassium and in particular phosphorous are needed more during flowering
and seed formation. Industrial hemp requires 105 to 130 lbs./acre (120
to 150 kg./ha) nitrogen, 45 to 70 lbs./acre (50 to 80 kg/ha) phosphate
and 52 to 70 lbs./acre (60 to 80 kg/ha) potash.
4. Growing Conditions
Hemp prefers a mild climate, humid atmosphere, and a rainfall of at least
25-30 inches per year. Good soil moisture is required for seed germination
and until the young plants are well established.
 5. Weed Control
Industrial hemp is an extremely efficient weed suppressor. No chemicals
are needed for growing this crop. Industrial hemp is a low maintenance
crop. There are no registered chemicals for weed control in hemp. A normal
stand of 200 to 300 plants per square meter shades out the weeds, leaving
the fields weed-free at harvest for the next crop.
Notice the canopy effect created by the dense planting. When properly
planted and cultivated, weed control is a non issue.
6. Time of Seeding
The best time to seed hemp should be dictated by the weather and soil
conditions, rather than the date on the calendar. Hemp can be seeded as
early as two weeks prior to corn provided that soil conditions are optimum.
However, seeding should not begin until soil temperatures have reached
a minimum of 41 - 46 deg.F. (6 - 8 deg C.). Hemp seed germinates within
24 to 48 hours, and emerges in 5 to 7 days with good moisture and warm
temperature.
 7. Plant Population
High yields of high quality fiber can be achieved with proper plant density.
Seeding rates of 250 to 400 viable seeds per square meter are probably
ideal, depending on soil type, soil fertility and cultivars. The seed or
grain production will require lower seeding rates.
This stand is ready to harvest. Note the uniformly dense population.
8. Breeding Characteristics
Generally, hemp is a dioecious plant ( a plant having the stamens [male]
and the pistils [female] borne by separate plants of the same species ).
However, there are three classifications of varieties:
- monoecious varieties - when male and female flowers develop on the
same plant;
- dioecious varieties - with distinct male and female plants;
- female predominant
varieties, obtained by pollinating dioecious females with monoecious
pollen.
9. Cultivar Types
There are two types of industrial hemp based on their use.
- fiber cultivars - with long stalks and little branching; (shown to
the left)
- seed cultivars - with shorter stalks, larger seed heads and may have
numerous branches (seed contains 30 - 35% oil). (shown to the right)
 
10. Rotation
Hemp can be grown on the same ground for several years in succession
but rotation with other crops is desirable. Hemp responds well to most
preceding crops. It is also possible that introduction of hemp in a crop
rotation might improve the soil health. In 1996, Kenex Ltd. of Canada observed
that hemp may significantly reduce the population of soybean cyst nematodes.
 11. Harvest
Harvesting of hemp for high quality fiber occurs as the last pollen is
shed. Harvesting for seed occurs 4 to 6 weeks later, when 60% of the seed
has ripened. Fiber hemp is normally ready to harvest in 70 to 90 days after
seeding. The end use of the product may significantly impact on the harvesting
method.
 Kennex Ltd. of Canada, is developing a harvesting system that will be
compatible with the new processing technology. For fiber production, the
crop will be cut, dew retted in the field, baled and stored or processed.
 12. Retting
The bast fibers are obtained by retting - a microbial decay of pectin,
the substance that glues the fiber to the woody core of the hemp stem together.
Retting is carried out in the field and depending on the weather, takes
12 to 18 days to complete. During retting, the stems need to be turned
one or two times in order to allow for even retting, since the stems close
to the ground will remain green while the top ones are retted and turn
brown. Retting is complete when the fibers turn a golden color and separate
easily from the mass to finer fibers.
 13. Yield
Based on yield data from 1995 and 1996 along with preliminary estimates
for 1997, yield expectations are between 3 to 5 tons of baled hemp stalks
per acre on well drained loamy soils in South Western Ontario.
14. Storage
For storage, the moisture content of hemp stalks should not exceed 15%.
The bales can be stored for a long time in dry places which could include
storage sheds, barns or other covered storage.
The information provided in this fact sheet is based on research sponsored
by
Kenex Ltd., RR#1, Pain Court, Ontario, Canada, N0P 1Z0. The information
reflects research data gathered from the test plots at Ridgetown College
and the
Kenex pre-commercial field trials at Pain Court. Information is based on
research
from 1995 thru 1997 at these two facilities.
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