Hemp Guide - 2020 - 14

PRODUCTION
it should be at least 99%. If buying seedlings, ask to see
documentation for the feminization rate for the seeds
used. If buying vegetatively propagated clones/liners, ask
about how the mother stock was maintained and if it was
generated from a clean stock program.
Some strains will perform in a wide range of climates,
others will do best under certain conditions. Some will do
fine in a greenhouse, others might not. Ask your supplier
or breeder for regional performance data regarding
greenhouse suitability, disease tolerance, insect
tolerance, greenhouse production, plant form, frost
tolerance and yield.
INFRASTRUCTURE NEEDS
Can I use my existing greenhouse to grow hemp?
Necessary infrastructure changes depend on the
genetics being grown, the time of the year and the
target product. Lighting is a primary concern. While autoflowering
crops will flower under any photoperiod, most
genetics are strongly photoperiodic, short-day plants.
Critical photoperiod varies by variety, but generally falls in
the 13- to 14-hour range. Therefore, young plants require
long days to remain vegetative. Night interruption or
daylength extension work equally well. Year-round flower
or seed production will require supplemental lighting and
light deprivation (black cloth) systems to maintain short
day conditions. Seasonal production needs will depend on
the specific time of year.
A few other infrastructure needs should be considered.
Summer greenhouse production will require active cooling
for most locations across the U.S. If growing to flower or for
seed, greenhouse height needs to be adequate to support
lights and light deprivation systems over crops that can
grow 4 to 6 feet tall. This isn't a crop for a low-gutter space!
Benching used for producing bedding plant flats might
work well for liners but will make working with mature
plants a challenging endeavor. Seed and flower crops are
best produced using drip irrigation. For summer production,
insect netting should be considered a necessity. All hemp
crops require strong sanitation: Floors and benching
should be tolerant of chemical cleaners and sanitizers.
Concrete floors are desirable, as dirt and gravel floors can
harbor insect pests.
CROP PROTECTION
What are the common pests and diseases of hemp
and how to control them? Most greenhouse hemp pests
are well known to commercial flower growers: thrips,
spider mites, aphids, powdery mildew and Botrytis top
the list. However, there are a few others, including hemp
russet mites and root aphids, that will be new to most
growers. Growers should spend some time learning
about these two pests.
Crop protection strategies for hemp vary dramatically
from those often employed for ornamental crops. First,
no PGRs are currently allowed for hemp crops. Second,
CBD hemp should be treated as an edible crop. This
means your chemical toolbox is much smaller than for
14 | 2020 GUIDE TO HEMP PRODUCTION
Growers must remove all male plants from their hemp crops.
Photo: Griffin Greenhouse Supplies, Inc.
ornamental crops. Additionally, while a small number of
pesticides are labeled for " industrial hemp, " this does
not mean they can be used on CBD hemp. To apply a
product on CBD hemp, " hemp " must appear on the label
as a crop. Finally, individual states often have specific
rules regarding pesticide use on hemp. Growers must
take the time to learn the requirements in their states.
One thing holds true across all states: Prevention is
key. Coming from behind on any crop is challenging. On
hemp, coming from behind can be a losing battle.
Cannabis growers in most states are familiar with
state-mandated testing for pesticide residuals, microbial
infestation and heavy metals contamination. We should
expect that these requirements will come to CBD hemp,
too. Start getting ready now by learning to prevent and
control pests before the flower stage as most growers
will want to avoid spraying late in the crop. Non-chemical
control of insect and mite pests is achievable with use of
biological control agents (BCAs). The key is deploying the
BCAs from the very start of production.
CROP FERTILITY
What does this crop need? Hemp is a moderate feeder,
and a balanced program will generally prove successful.
Most growers will use a two-part system to provide
adequate calcium to the crop. Fertility rates of 150 to
200 ppm are common once the crop moves past the
young plant stage. It's important to provide a proper

Hemp Guide - 2020

Table of Contents for the Digital Edition of Hemp Guide - 2020

Hemp Guide - 2020 - 1
Hemp Guide - 2020 - 2
Hemp Guide - 2020 - 3
Hemp Guide - 2020 - 4
Hemp Guide - 2020 - 5
Hemp Guide - 2020 - 6
Hemp Guide - 2020 - 7
Hemp Guide - 2020 - 8
Hemp Guide - 2020 - 9
Hemp Guide - 2020 - 10
Hemp Guide - 2020 - 11
Hemp Guide - 2020 - 12
Hemp Guide - 2020 - 13
Hemp Guide - 2020 - 14
Hemp Guide - 2020 - 15
Hemp Guide - 2020 - 16
Hemp Guide - 2020 - 17
Hemp Guide - 2020 - 18
Hemp Guide - 2020 - 19
Hemp Guide - 2020 - 20
Hemp Guide - 2020 - 21
Hemp Guide - 2020 - 22
Hemp Guide - 2020 - 23
Hemp Guide - 2020 - 24
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