and the CO 2 is supplied using a tank. Each
of these units is connected to a sensor so
that they go on and off automatically. In
temperate areas the air conditioner remains
on only a small part of the time, except
during the summer when it may be called
on for heavy duty work. The air conditioner
also dehumidifies the room. A small sized
dehumidifier can keep a room at desired
humidity when the temperature is within the
acceptable range.
Grow spaces located in basements or
attics may get cool during the winter. An
electric or gas heater designed for indoor
use is often used to increase the
temperature. Electric heaters raise the
temperature, but decrease the humidity of
the room because no additional moisture is
added to the air. Gas heaters vented into
the grow space provide CO 2 , moisture and
heat to the plants.
Plant roots are very sensitive to cold
temperatures. Containers placed directly on
a cold floor lose their heat. To conserve
warmth the units are set on a pallet or the
floor, or it is covered with a layer of
styrofoam sheet, which is both an excellent
insulation material and light reflector. Heat
mats and heating cables which are
thermostatically regulated to keep trays and
soil in the mid-seventies are sold in many
garden shops. Water in reservoirs is often
heated using aquarium equipment.