While
a greenhouse is a natural solar heater there are many situations where
the optimum temperature still cannot be reached. Colder environments
require a greenhouse heater to retain their temperature. Heat escapes
through the glass very easily at night, and many greenhouses are used
in the winter to allow plants to grow all year long.
Most greenhouse heaters are electric, heat the air and circulate with
a fan. They are cost effective, and many are small and portable allowing
them to only be used when needed and stored during summer and warmer
months. Very humid environments can cause problems with the electric
heating element, but they are all grounded to prevent shock.
Another type of greenhouse heater looks more like an extension cord
with the accompanying plug at the end. The cord is buried in the soil,
or installed underneath the greenhouse benches, and keeps the surrounding
soil at a constant 70-80 degrees. They plug into a regular socket, are
grounded against electrical shock and have built in thermostats to automatically
turn on when soil temperature drops.
