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FEATURE

GREENHOUSE TECHNOLOGIES

FOR CANNABIS GROWING

With any greenhouse design, it is important to keep the end purpose in mind right from
the start. Greenhouses are built to provide the crop (whatever it is) with the ideal growing
environment in order to maximise production efficiencies and yield. A cannabis greenhouse
should be sized for future demand, but with scalability in mind to accommodate longer
term business goals. It should be designed for multiple stage extension plans, and a little
extra time at the beginning can save additional costs down the line.

here are four stages of growth for system and good environmental controls. greenhouse or tunnel structure that is used
cannabis production, and growing Blackout curtains (also known as light to produce other horticultural products,
Tshould be zoned accordingly: deprivation screens), irrigation and however there are some caveats. Cannabis
fertigation systems are all designed is photoperiod sensitive, i.e the amount of
• Zone 1: marijuana mother plants by greenhouse industry experts to be daylight it receives determines whether it
• Zone 2: marijuana clones (cuttings) centrally controlled for multiple zones. flowers or remains in the vegetative state.
• Zone 3: marijuana in the vegetative As such, conventional greenhouses and
stage The above information was extracted tunnels can only produce a single crop
• Zone 4: marijuana in the flower stage. from an article entitled How to Build per year, typically planted in spring and
a Greenhouse for Cannabis Production harvested in autumn. The timing of the
Marijuana growers are used to growing (written by Leigh Coulter in Greenhouse planting is critical, especially in tunnels
in smaller spaces than most commercial Product News, www.gpnmag.com). that tend to have lower roof heights:
growers, but where large zones increase Landscape SA then posed the following planting too early will result in plants that
production efficiency, they also increase questions to a few South African are too big for the structure, and the top
crop risk from disease or infestation greenhouse companies. Their responses parts where the best flowers are located
spreading. When one considers the are given below: will be in the hottest and most humid zone
monetary value of a marijuana crop, of the greenhouse. Here they will be more
there is a reasonable trade-off between Q: What type of greenhouse struc- susceptible to mold infections late in the
production scale zones and isolation ture is required to grow cannabis? flowering stage.
segmenting. Does this differ from structures for
other horticultural products? By adding light deprivation curtains,
Zone segmentation can easily be achieved the cultivator can induce flowering by
with inside gable walls and sidewalls, a artificially shortening the day. Inversely,
properly designed heating and cooling Lawrence Sharpley, CannaConsulting: plants can be kept in the vegetative state
Cannabis can be grown in any conventional

12 Landscape SA • Issue 93 2020