In article ss,
"gunner" wrote:

"Steve B" wrote in message
...
In another newsgroup, there's a discussion about heating a greenhouse.
Electric heaters were mentioned. Also kerosene, but comments were made
about fumes and stickiness. Someone recommended a plain propane barbecue.
It was stated that the CO2 would be good for the plants. I was wondering
about the CO produced, and what the levels would be.

What is the best/worst ways to do supplemental heat in a greenhouse?

Steve


The best is the least inexpensive method, whatever that is for your setup
and area. I have seen setups area in more temperate areas use a closed loop
system w/ a hose coiled under compost. Others; water barrels painted black
for heat sinks, These tricks don't work here in the cool PNW maritime
climate. The C02 could boost plant health, but it would be a waste of time
it your plant are dormant as most are in winter. If you are a commerical
grower then heating is a cost of business and you usually get a bit of heat
from all those 1000w bulbs.

I am building warming benches (bottom heat ) w/ heat cables( ~1$ a foot+
thermostat), but electricity is relatively inexpensive here compared to
fuel. I can put plants on the warm sand and if necessary, enclose them with
bubble wrap, all inside the house. Old christmas lights wrapped around
plants can help, the old 100W bulb is good for a few feet in an open GH, I
would use a blower if you use a propane BBQ grill, definate test by temps at
various feet away from heat source.

here are the commericals setup: http://brae.calpoly.edu/CEAE/greenhouse.html

Hmmm ...

Do plants need Oxygen as well as CO2?

The root growth for new plants I believe needs Oxygen more than CO2.
If one puts the propane barbecue heater inside the greenhouse this may
be bad for the plants because the heat would use up the Oxygen. If I
went with a propane heater it would be a camper style heater in which
the heater is outside and blows the heat inside the greenhouse OR has an
exhaust vent to the outside. Electric mats under the plants are probably
the best way to go. Electric is also nice for the over head watering
systems.

Electric can be a problem if the greenhouse is not near a power source.
So therefore ... propane.

Enjoy Life ... Dan

--
Garden in Zone 5 South East Michigan.