How do you heat your greenhouse/hoophouse?

[tgplp]

Hi all, I have a small (8x7 feet, I think) hoophouse that I'd like to heat cheaply to extend my growing season, maybe even grow all year. I don't really know the first thing about heating, though, and need something very cheap! I'd love to hear everyone's ideas and how they heat their greenhouses.

Thanks!
Taryn
P.S. How about... Christmas lights?

[biscgolf]

i heat my 20x100 greenhouse with propane currently. it is darn expensive but dependable and consistent.

i aspire to do geothermal supplemented with propane for my next one which will be cheap after the initial outlay and should also be dependable and consistent.

wood is my cheapest option but is a fairly constant chore.

for something the size you are talking about i would think propane or electric would be your best options, neither one of which is going to be particularly cheap. a wood stove would likely be overkill for that size space.

much also depends on how warm you aspire to keep it... are you overwintering fairly hardy plants (40 degrees) or growing tropicals (seventy degrees)?

[saltmarsh]

4'W x 20'L x 7'H heated with electric oil radiant heater. High heat draws 1275
watts. Comes with remote that works through the plastic. Currently 36
degrees outside. Heater set on 65 degrees, temp 18' from heater is 55
degrees inside. Claud


http://www.homedepot.com/Appliances-...&storeId=10051

Rube Goldberg Heating System 10-27-2011 006.jpg Rube Goldberg Heating System 10-27-2011 009.jpg Rube Goldberg Heating System 10-27-2011 017.jpg

[bobberman]

Before you start to heat it you better make sure you have a double layer of plastic or it will not hold the heat!,.

[SEAMSFASTER]

I recently helped complete the major part of construction of a 66'X12' solar pit greenhouse which is dug 8' into the ground. It depends solely upon geothermal energy, but we installed a wood-burning stove just in case.

A few nights ago the low temperature outside was 0° F but 38° inside the greenhouse. So geothermal heat energy can be viable. We still have a few additional projects to complete on the inside, after which I think with can keep the temperatures above 45° even if it gets down to -20° outside, with the expecatation, of course, that we get sunny days. For example, we plan to get additional heat energy (and CO2) from animals and composting which will be kept inside the structure.

I recently heard about very energy effecient "pellet" stoves. My understanding is that these have a hopper which is on a timer or thermostat, so they automatically drop more pellets in when needed.

With little knowledge, I cannot recommend one brand over another. Perhaps someone else has experience with these? I've also heard of ceramic-based stoves.


Another method I've tried is to heat the soil with buried pipes which circulate warm (80°) water. The heat from the soil radiates up and can help reduce heating costs somewhat.


In 2010 I used this system for a small (2'X33') tomato bed. When I transplanted on March 21st, the soil temperature was 74° in the bed, but 40° in the main garden.


I supplemented heat with a small, round, electric heater placed inside a 10" diameter pipe. I left gaps between the sections of pipe to allow warm air to spread throughout the bed. Unfortunately, I only used a single layer of plastic, so heating costs were still relatively high.

Attached are a few pics of the setup. The fourth pic was on May 23rd, ahead of a record-late snowstorm that dumped 2" of wet snow.

[bobberman]

Another tip I think is worth while is the second layer can be a think 3 mill but put it inside. The thin layer will allow more light than the 6 mill. You need the heavier on the outside area. I also think that waer 50 gallon drums is a mut no matter what kind of heat you have because it can maintain a more constant heat at night and actually cool the greenhouse during the day! I take my inside layer of plastic off in the early spring when tems get too hot!

[LuvsToPlant]

Originally Posted by tgplp

Hi all, I have a small (8x7 feet, I think) hoophouse that I'd like to heat cheaply to extend my growing season, maybe even grow all year. I don't really know the first thing about heating, though, and need something very cheap! I'd love to hear everyone's ideas and how they heat their greenhouses.

Thanks!
Taryn
P.S. How about... Christmas lights?

A greenhouse and a hoophouse are two different stuctures and serves different purposes.
Sounds like you have more of a hoophouse...which is used to extend the growing season....I see that you mention that is your intentions.
The old propane heater is useful to help on freezing nights.

The greenhouse on the other hand is more of what you would use year round with a heat supply and good ventilation.
Our hundred footer are heated by oil.

[Marymcp]

My husband, scavenger and pack rat, found these radient heaters discarded somewhere and has rewired them for me to use in the garden. I don't have a hoop house *yet*, two weeks ago we set up tall patio chairs around the raised beds and strung cotton sheets across. Two of the heaters were placed on milk crates in the walkway between the two 6'-long beds. Worked nicely. Outside temps were about 32°, inside at 38°. I believe they could work better with a better setup, like plastic over the hoops. We think the heaters are the type you find in bathrooms to heat the room while showering.

[bobberman]

You can put a second layer of plastic over a hoop house by running ropes over the hoop house every ywo feet. This will seperate the layers of plastic and give them a air space. The hoop hopuse is like said is usually for extending the season for a month or so but is very had toi heat. One layer of plastic will loose 90% of its heat quick but the second layer will drop heat loss down well below 25%

[saltmarsh]

It's been about 2 weeks since I posted the first photos, and a lot has happened since then.

We've had a couple of days with winds 20 to 25 mph with gusts to 35. This gave me a chance to try it with the plastic up, down and part up. It doesn't have any problems with wind, but I normally leave the plastic on the north side down and raise the plastic on the other sides when the temp is above 52 degrees outside. This is to keep the plants as hardy as possible going into the winter months.

We normally have a few days of warm weather before Christmas and I believe this is it. As you can see, these photos were taken about noon today and as the thermometers show, it's about 80 degrees 6 feet above the ground, about 71 degrees 2 feet above the ground and about 77 degrees 2 inches below the ground surface.

The temps have really dropped since Thanksgiving. We've had numerous nights with temps below freezing (26-29degrees), 2 nights down to 22 degrees and 2 inches of wet snow, a week of cold overcast weather where the sun didn't shine and days of cold rain.

Quite the trial for the plants and the frame.

All the plants are doing fine and seem glad to get a little fresh air and sunshine for a change.

I normally leave the heater set on 65 degrees when the forcast calls for temps in the 30's and 40's and raise it to 75 degrees when the forcast calls for temps below 26 degrees. The little fan pulls air from the top of the west end and blows air on the heater at the east end. The temp near the heater stays about 10 degrees warmer than the west end. With the heater set on 75 degrees, when it got down to 22 degrees outside, the coldest it got down to farthest from the heater was 50 degrees.

Any time the weather is going to be below 35 degrees, I install 10 x 20 foot plant covers on the top and 3 sides, leaving the south side open so the sun can shine in if it isn't overcast.

With it closed up and the sun shining and an outside temperature of 42 degrees, the temp inside goes to 101 degrees in about 30 minutes. Talk about an easy bake oven, so I installed another small fan near the top of the east end and controlled by a thermostat which I leave set on 75 degrees. Because the thermostat is mechanical rather than digital, it takes a little longer to warm up than the air around it. This lets the temp go to about 90 degrees before the vent starts pulling air from the outside and keeps the temp inside at about 78 degrees throughout the day. This has really helped as the temperature difference between the top and bottom of the frame is only 3 degrees (78 on top and 75 down low). It has also helped with lowering the humidity inside.

I'm eating fresh vine ripened tomatoes and they are goooood.

As long as I don't have a power outage, it looks like we're good to go. Claud

[LuvsToPlant]

Originally Posted by bobberman

You can put a second layer of plastic over a hoop house by running ropes over the hoop house every ywo feet. This will seperate the layers of plastic and give them a air space. The hoop hopuse is like said is usually for extending the season for a month or so but is very had toi heat. One layer of plastic will loose 90% of its heat quick but the second layer will drop heat loss down well below 25%

I agree with bobberman on the seperation of plastic...improves greatly.
We use blower fans special designed for greenhouses to keep the plastics' from touching....but I like the idea on a thick rope or anything of the such to separate on a hoop house.

saltmarsh...nice hoophouse!
...more of a hoophouse to me than a coldframe.

[saltmarsh]

"saltmarsh...nice hoophouse!
...more of a hoophouse to me than a coldframe."

LuvsToPlant, I agree.

As long as the electric stays on, it's a hoop house,
but if the electric goes off, it'll be a cold frame. Claud

How about a winterized trellis?

Whatever it is, it's a sure cure for the winter time blues.

[bobberman]

Instead of rope old cut up hose will work to seperate the plastic! Hook the hose over the plastic at the plastic pipe with a wire then put on the second layer! If it gets too hot on nice days just leave the ends open!