The Urban Farmer, Issue #041 * Ventilation, Humidity, Temperature &
"Gardening requires lots of water - most of it in the form of
VENTILATION: A BREATH OF FRESH AIR
How important is air flow to a
Air flow is arguably one of the most important aspects of a grow room or
greenhouse. Not only does it deter mould and fungi developing, but it also
provides much needed CO2 for the plants overall growth and development. A well
ventilated room will yield more than a room with no ventilation. The only time
this is not the case is if the room is controlled with a complete climate
control system. In such a room, air-conditioners and a CO2 injection system is
essential. CO2 is then introduced not by airflow but through a designated
injection system. It is important to note that CO2 injection works best in a
completely controlled climate. To understand why ventilation is important
consider the goal of setting up a greenhouse or grow room. The aim is to mimic
the outside environment in a controlled and therefore higher yielding area.
Are oscillating fans needed?
An oscillating fan is necessary for adequate air movement in the room itself. It
helps to move warm air in winter and cool air in summer evenly through the plant
canopy. Oscillating fans help maintain consistent room temperatures
How important is Humidity &
It is extremely important to monitor & control relative humidity around a
hydroponic crop. Relative humidity should be in the range of 50-70% and
temperature should be around 70-80 degrees F. during the day and 65-72 degrees
at night. Extremes in temperature should be avoided. Temperatures above 90
degrees stop plant development.
High humidity increases the risk of molds and mildew developing as well as
encouraging an irresistible habitat for pests like spider mite & scaridfly.
High humidity also reduces transpiration, which in turn reduces circulation in
the plant of essential elements like calcium.
Low humidity, or dry air, can decrease the likelihood of fungal diseases but it
also increases transpiration in the plants which can in turn dry the leaves and
growing points out excessively. This can produce lack of pollination in tomato
crops because the growing point dies. This of course affects the overall harvest
of the crop. Increased transpiration in the leaves also affects the fruit
already on the plant. Fruit can die or flowers rot because less water is being
channelled to the fruit/flower.
A CADILLAC GARDEN: CLIMATE CONTROLLER
If you have an enclosed growroom or a greenhouse, you have
the option of automating your garden to strive for the "perfect environment".
Basic Garden Climate Controller
The cheapest and most basic garden climate controller usually controls
only temperature and humidity and runs your exhaust fans when needed. For an
small additional charge, CO2 controls can be added to most basic models. This
allows you to coordinate all of your environmental controls in one place without
spending hundreds of dollars on a controller that is more sophisticated than you
need. Most home indoor gardens can be handled effectively with just the basic
Complete Garden Climate Controller
If you have a more complex hydroponic garden setup or need a fully-automated
system, you can purchase a complete garden climate controller. These are
especially useful if for people who travel frequently and cannot maintain their
garden regularly. They typically include a timer with several outlets to control
different banks of grow lights, along with outlets and thermostat controls for
your exhaust fans or dehumidifiers. Water pumps are activated by a timer and
many climate controllers include a photo sensor, allowing you to conserve energy
by running your pumps only when the grow lights are off.
Another advantage worth the extra expense of a complete garden climate
controller is the control it gives you over your CO2 system. Most controllers
allow you to coordinate the infusion of carbon dioxide with the exhaust fans to
cut down on wasted CO2.
Hydro Tip of the Month
One of the best things about hydroponics is its
versatility and adaptability. Your choices for this gardening method are wide
open. You can grow some heirloom tomatoes in a 5 gallon "bucket bubbler",
gourmet hydro herbs on a kitchen windowsill, or sugar baby melons in a large
bedroom farm. You can create a garden from 2-liter soda bottles and hang it on
your patio fence. Or you could spend thousands on a state-of-the art NFT or
aeroponics system. Get started on your decision here:
We hope you have enjoyed this issue of The Urban Farmer Ezine. Each month, we will bring you another inspiring photo, gardening quote or idea, plus fresh new hydroponics news, techniques & products.
Insiders tips to get you growing...
~Stella and Simon from