I am hoping to grow plants with hydroponics starting in January. My
problem is that my greenhouse does not hold heat very well. I have
tried methods like hanging fans from the ceiling to pull the heat back
down to the floor. This works but not well enough if it is 30F outside,
the house is at 55F.
I have no duct work run because of my limited budget. I have the house
insulated. It has a 10000 BTU propane heater and it seems that all of
the heat escapes out of the top of the greenhouse. It is a clearspan
I need to reside at 70F.
Any suggestions would help.
All or nothing is the wrong approach.
Chuckie in the frozen north zone 5
How big is the green house? Can you line the south side of it with 30 or 55
gal drums filled with water and painted black or dark green? With the sun
shining on them during the day, they will hold the heat most of the night.
If it were big enough you could put a single row of drums on the south side
and stack them 2 high on the north side. I would even try 5 gallon plastic
buckets if you don't have room for drums.
Heat the benches, not the air... you can get good growth with root zone
heating and a cooler air temp (with some crops, it's preferable.) One of the
Ball Red Books done in the last 10 or so years has a section on heating
costs and choices. Bubblewrap may also help with insulation
OF the house itself.
I have bubble wrap insulation covering the north and south walls and on
the east and south walls to bench height.
I think I will try the barrel and water idea.
The dimensions of the greenhouse are 12W x 20L x 8H.
Chuckie in the frozen north zone 5
In addition, if the barrels are the same height, you can lay boards over on
top and use them for a shelf. I saw this idea at the Botanical Gardens in
Cheyenne, WY. When asked, our guide said that the night before, the heater
came on only once when the temp got down to between 20 and 25 degrees F.
That building is much larger and they had drums stacked three high along the
North wall, and a single layer along the south wall.
Go to any car wash in your area. We throw away at least one 55 gal drum
every week. They'll be happy to give it to you, instead of having to send it
to the recycler or dump. If you're lucky they might even have a few drum
plugs laying around the equipment room.
Because many car washes still use ammonium bifloride (ABF) or hydrofluoric
acid (HF) be cautious of drums marked as wheel cleaner. If you use them,
wear gloves and flush the inside with water several times.
Water heats and cools very slowly, so this will work both ways, in the day
time the greenhouse won't heat up as quickly, and at night it won't cool as
quickly. Which may be to your advantage in the summer.
I think your problem may be a heater that is too small. According to the
heating calculator at http://www.littlegreenhouse.com/heat-calc.shtml , you
will need 30,000 BTU to heat your greenhouse on a typical coldest zone 5
night of -15F to an inside temp of 70F. this is assuming that you have the
greenhouse with the inflated double polyethylene roof and sides.
If you are growing anything other than warm weather crops , like tomatoes,
or tropicals, you can get away with 40-45 temps if you use rootzone heat of
In iehter case, a larger heater is needed
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