ASK THE EXPERTS
I have a few questions on hydroponics. I am currently working
with a team and we are making a hydroponic garden out of an
old shipping container. So far we plan to use PVC pipes as the
main system and purple lighting (almost like purple party string
lights) as our source of light around the container. One of the
things we are looking into is, what are common problems we will face and how
to find the optimal, temp, humidity, pH, etc. in the container so as to avoid any
unwanted pests (algae, gnats, mildew and other plant diseases). If you know
any good tips or ways to go about experimenting please let me know.
– Sian
Q
Hello Sian,
Shipping containers have been turned
into highly successful hydroponic
systems in many different climates
and they can be a good choice for
a compact and productive indoor
garden. The main considerations with
this type of set up are airflow, humidity
control, plant density (i.e not overcrowding the system),
the correct type of lighting and temperatures. Since the
volume of air inside the container is highly limited, factors
such as heat and humidity can build up rapidly when plants
are large and grown at a high density. Humidity buildup
inside a shipping container often leads to condensation on
the roof which falls onto the plants, thus greatly increasing
the risk of a disease outbreak. For this reason, the rate of
airflow into and out of the container must be sufficient to
remove moisture from the air and control temperatures.
The recommended rate would be at least one complete
air exchange between the inside of the container and the
outside per minute (60 air exchanges per hour) and in some
climates, dehumidification may also be required. This will be
more important as the plants grow as a large surface area of
foliage releases much more water vapor into the air.
Secondly, temperature control is also vital. In warm,
tropical climates, shipping containers with chilling (i.e.
climate control) are used to grow cool season crops such
as lettuce when conditions outdoors are too hot for good
growth. So the requirement for heating and/or cooling
will depend on the local climate where the container is
A
sited‑—insulated shipping containers are a good choice
where a high degree of heating and/or cooling is required
to achieve the optimum levels for plant growth.
Lighting for crop growth is also very specific, horticultural
LED lamps are recommended for very confined, small spaces
as they don’t put out the high heat of HID lamps, they can also
be placed just above the plants without the risk of leaf burn.
Light for plant growth is very specific and a little different
from lighting used for other purposes, so it would be a good
idea to consult a reputable supplier of hydroponic equipment
to make sure the correct type, layout and intensity of lamps
are chosen. Algae growth can be prevented by making sure
the nutrient solution flowing inside the PVC pipes and in the
nutrient tank is never exposed to light (lightproof covers assist
with this). Fungus gnats can be prevented in a similar way by
covering any exposed, damp growing medium and nutrient
solution, and preventing algae growth (gnats are attracted to
moisture and organic matter). Other insect pests are more
difficult to prevent, however, screening over air intakes, vents
and a small double door entry into the shipping container may
help as well as carefully inspecting any plant material coming
into the container for pest infestations. Daily checking and
adjustment of the hydroponic system's EC and pH should
be sufficient to manage the nutrient in a recirculating PVC
system, however, it would be advisable to make sure you have
a high-quality, clean water source or use RO water. Good luck
with your container garden!
Kind regards,
Lynette Morgan
Dr. Lynette Morgan holds a B. Hort. Tech. degree and a PhD in hydroponic greenhouse production from
Massey University, New Zealand. A partner with SUNTEC International Hydroponic Consultants, Lynette is
involved in remote and on-site consultancy services for new and existing commercial greenhouse growers
worldwide as well as research trials and product development for manufacturers of hydroponic products.
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Maximum Yield USA | September 2016