I've been using an elec heater I bought from Wal-mart in my HFGH with an extension cord for the last 3 years with no problems. I use a heavy duty extension cord (cost about $30) and the heater was a heavy duty type I got on clearance for $12. It looks like a "milkhouse type heater" you can get at any farm supply store.

I used an electric baseboard heater last year. It too was on a heavy duty extension cord.

I had no problems at all and it worked well.

Cindy

I use two direct-wired baseboard heaters. They are economical to buy, run and seem to work well.

I have three of the $12 heaters. If you have GroundFault breaker it's not a problem. The warning is because it could short out. And the main problem is rust. But at $12 you're not losing a lot. I bought one of the so called greenhouse milk heaters @ $59 and it only lasted one year.

I use an oil filled radiator type and a small desk fan off to one side blowing through it.

Why? You ever seen the bright sparkle that comes out of a "milk house" style heater when a bug gets sucked through it?

:)

I got one of the "milk house" style heaters from FarmTek and will have it on a thermostat and a long heavy duty (12-3) extension cord. GFI sounds like a good idea, I'll change out the outlet.
Manufacturers warn against this because, yes, there can be problems but we simply need to keep track of our equipment because, as someone pointed out above, they will rust out, short out, etc. That is the risk we take if we don't want to spend the big $ for a specially designed, moisture proof, idiot proof, greenhouse heater.

"there can be problems but we simply need to keep track of our equipment"

"That is the risk we take if we don't want to spend the big $ for a specially designed, moisture proof, idiot proof"

Um... not to mention the "attic" fans some reckless people are using as exhaust fans!

Got mine on sale, two 1175CFM fans with thermostat at 30 bucks each!

But play it safe, Electricity can, and will, kill you every chance it gets. If it can't kill you it will try to burn down your greenhouse when you are not looking.

I misspoke earlier. I do have at least 3 of the Wal-mart $12 heaters but I remembered I didn't use them all in the greenhouse.
I do have a 200AMP dedicated panel will all ground fault breakers in every outlet even though it was only required to have one per breaker.
Here's pictures of the one's actually in use.
Old ceramic heater I've had for years.
{{gwi:293159}}
Oil filled radiator type.
{{gwi:290525}}
The $12 milkhouse heater.
{{gwi:290523}}
The idoit proof, waterproof, rust proof, heater that cost way too much to operate.
{{gwi:308237}}
My backup kerosene heater set at 38* which used less than 5 gallons all winter. Smallest BTU I could find that worked on a thermostat.
{{gwi:308238}}

Cactus,

What temp do you keep your greenhouse at during the winter months?

Cindy

Holy Cow!
Can you just imagine 40,000 btu's in a HFGH? LOL
seriously, I had a small home-built 6x8 when I lived in AK.
I only used 2 ceramic heaters and a small fan. It didn't keep it balmy, but did manage about 50 at night considering it was 0 outside. My electric bill did send my wife into a tizzy though. For fresh air, I only had a 1" pipe going outside (near the fan)
A heated GH is still much cheaper than therapy for those gloomy winter days.

Tom

Cindy, I keep it around 45-47. If one of the electric heaters go out the kerosene is set for 38*. But must have electricity to ignite. Then if I lose power I have a manual kerosene and gas logs and 80lb propane tank.
Now I just need to make sure my alarms are working correct. That's after I get all the plants in this weekend.

Cactus,
I remember a while back you talking about the wireless thermometer. Where did you buy it? I'd like to get one. I've had some close calls in the past.
Tom

oregon_veg, I have one that I got at Radio Shack. It has a 300 ft range. You may only need one with 100 ft range. Wal-mart carries those now. Back where the Home improvement supplies are. (foam insulation, window coverings, thermometers, etc). Also you can find them at Lowes and HD. Or even a drug store.
I also have one that is wired. I got it way before I had the wireless one. It has a 150ft wire that barely reaches inside my back door. It was more expensive than the RS wireless one.

Hi Tom and all:

I have to agree that the electric bill is gonna be a bugger. But this is my hobby...not my business. If I spend a few bucks, so be it. As you said, it certainly beats therapy.

I'm also using 2 small electric heaters from Home Depot on two seperate thermostats...so far so good. My minimum temp is going to be 55 in the depths of winter. Currently I'm holding 60 but that will change in Dec-Feb I think.

By the way, we had a windstorm here Sunday...50 mph gusts. The greenhouse rattled a bit but nothing flew off...LOL

Dave
Milwaukee

I finally got mine dialed in. I have three outlets in the greenhouse all on seperate 20 Amp Circuit breakers. I bought two really nice heaters with a digital thermostat for a real good price that can be programmed anywhere from 44 degrees on up. Since I learned that it could take up to 9000-10000 btu's to heat my zone 5 Harbor Freight should the temps get down to -20 I have each heater on a seperate outlet and those outlets only are used for each heater. The third outlet I have for my fan and radio or whatever else I want to plug in. I also bought 50/50 shade cloth and an autovent vent opener that raises the vent should the temp in there ever reach 60 degrees (that's what I have it set at). Then for my fan, I have it plugged into a "thermostat ductstat" that has a climate sensor that will kick my fan off and on if the temps reach the level I have it set for (60 degrees for my purposes). The "thermostat ductstat" can be set anywhere from 45 degrees on up as well. My fan is real nice because it's a clip on and it is plastic and has no guard on it. The clip-on feature allows me to keep it up high and out of the way while my heaters are on the floor. I've got this baby dialed in real tight.

All this stuff is for grafting conifers and deciduous material and for propagating cuttings of shrubs and growing my seedling understock. I'll provide the link to my heater and fan. The thermostat ductstat I bought at a home improvement store and the autovent I ordered off the internet for about 35 bucks. The shade cloth I bought from Gemplers in a 12 x 20 foot size for around 35 bucks.

Heres the link for the heater (It's bad!!!, real bad!!!!) They (Charley's Greenhouse) sells the same thing for a hundred bucks. These guys 60 bucks. The only thing you need to be aware of is that they call it a smart heater because it automatically selects which setting in terms of amps/btu's etc. at which it runs on. In other words, You can't plug two of these into one outlet that is rated at 20 Amps/120 Volts. Anyways, enough jibbering...here's the links.

Dax

Model DFH 480M DeLonghi fan heater - The Heater Shop

The Autovent: (The best deal on the internet)
Bayliss XL II Model

The Fan: I wanted something I really liked so I spent 40 bucks.
7" Clip-On Compact Fan (Scroll Down)

Gemplers Shade Cloths: (This was an impulse buy so I don't have any idea if I got a good deal or not.) It's big so I can simply throw it over the entire greenhouse and anchor it with bricks. 34 bucks.
Gempler's Shade Cloth's

I'm still waiting on the fan but everything else is installed and dialed in. I'll post some photos when I get the fan on the 21st.

Dax

Actually the heater I'm going to run at about 50 degrees and the fan just below that temp to keep the air circultation moving between each. This is still an in process thinking ordeal for me, but I really do I think have it dialed in pretty well.

Dax

Hi
I've used them off and on for many years. I live in zone 10 Florida so heat is much more of a problem than heating but we do get cold snaps.Just enough to kill a prize orchid lol
Have never figured out what to use as a wall covering
because even during the coldest weather when the sun comes up it will cook everything .So have left two walls open
and use the space heaters.
I'm now renovating the shadehous and I'm going to heat the 150 aquarium and 900 gallon pool to the mid sixties as a low. Don't know if this will work but I'm sure it won't be able to frost but there will be cold spots.
Can you imagine the steam this will produce during the
30's lol
gary

Hi, I've been busy all day and just checked to see if my fan showed up and it did so I hooked it up and took some photos of my Grafting Setup, etc.

My Wall Panel with three outlets. The outside two are each for a heater, the middle outlet I have my 'Plug-In Termostate Ductstat' plugged into with my fan plugged into it.
{{gwi:308239}}

A close-up of this 'Plug-In Thermostat Ductstat' which I calibrated earlier this morning when the temp in the greenhouse was 45 degrees F. Now whenever the temp is 45 or higher the fan automatically kicks on. This product is rated at 125V AC, 5 Amp Max. It's made by Suncourt TM.
{{gwi:306817}}

The Fan which is very nice and very powerful! It's made by Cafranmo and it's called 'Super Safe Compact Clamp Fan'.
{{gwi:308240}}

My 'Grafting Box' which is 12" deep and I'll be doing the grafts and completely covering the union where the scion is attached with the budding strip and will be not be tenting any of the grafts due to the fact that the sand will always be moist (This makes up for the high humidity needed)... and also if I were to tent them in this small greenhouse I would have a very difficult time controlling/keeping the temps in a tented area at the desired temp of 45-50 degrees F if I "was" to tent it with poly. *This is a good little trick to know about*
{{gwi:308241}}
*Also, The top to the box should I ever want to use it for holding my nice ridid flats I purchased, is made so that the flats edges slide right in between my 2 x 4's making another quote-unquote "bench" to hold another 6 flats!*

How my benches are set-up on the right side of the greenhoue and the placement of the heater, and the other heater being caddy corner to the heater shown in the photo.
{{gwi:308242}}

My 'Bayliss XL II Model (Autovent)...which worked like a million bucks today. As soon as the temps got to be 60 degrees F in there it brought the Vent right up...and later when it cooled off "she" was shut!!! I love it!!!
{{gwi:308243}}

Then the last photo to tie this all together. My Conifer understock just waiting till December to be brought into the greenhouse to "warm up"!
{{gwi:308244}}

And of course I have the 50% Shade Cloth and a Wireless Thermostat in my home so I can moniter the temps in the greenhouse and run outside if necessary and throw the shade cloth over it!

It's nice to have it all done! Thanks again for everybody's input.

Best Regards,

Dax

The warning about moisture is about rust and possible shock or shorting hazard. If used with a gfci (Ground Fault Current Interuptor) protected circuit that is tested regularly it should be ok.

The warning about extension cords is due to the amp draw the heaters have. Too small a size of conductors in your cord will cause them to heat up even beyond the temperature rating of the cords insulation. To minimize this possibility when I put my heater in the greenhouse I will use an extension cord
with #12 awg wire. most home outside extension cords us #16
to small. Some better cords use #14, but the best with the minimal heating of the wires thats available at hardware stores is #12 awg.