Heating our BC Greenhouse here again this winter. No biggie.... Have a over sized furnace which does a great job. Does not cost that much to heat by propane. Zone 5 here but house is NOT kept at 58.... That is quite high....!

Mike - have you tried setting up a tent of sorts and just heating a smaller space instead of heating the entire structure? Does your greenhouse have insulation, water barrels, or any other method of heat retention?

I haven't insulated the greenhouse this year. It's my first year with this house. My old gh wasn't able to keep temp no matter what I did. This one should be better. Next winter, I'll work on insulating the glass.

I've taped, caulked, and sealed the best as I could.

The way the gh is designed, I can't really separate it into different zones.

I wonder out loud if one could heat those harbor freight GHs in zone five where I am at?

I'm heating my 6x8 greenhouse this winter, but it is small and I live in Zone 8a (SoCal High Desert). Low temps only get down to the high 20's during the winter. During the day, the inside of my GH, even with the door open and the vent popped, will hit temps in the 90's. If I forget to open it up, it will hit 105+ inside. Basically, about 40-50 degrees above ambient temps outside.

So far the 18 tomatoes, 18 hot pepper/bell pepper seedlings, bunching onions, 7 artichokes, and 2 zucchini plants are loving it!

I keep the GH at about 42-44 degrees at night...

I'm in Ohio, zone 5; cold gray days ahead.
I'll heat it back up again when i start geraniums in a couple weeks. The greenhouse ( 18' x 28') uses propane heat. Wish i had a gas well on the property for free heat.
i've found that seeds,etc are minor expenses compared to heating.

Where a bouts in Ohio? If you don't mind me asking.

Do you use cuttings or seeds?

I'm heating mine (24' x 48', Twin-wall polycarb) for the second winter, using natural gas. Minimum temp is set at ~50 degrees, and when things heat up on a warm, sunny day the controller is programmed to open up one of the vents. Maintaining temps between 50 and 70 seems to be a good compromise for me, with plenty of things in flower (including a few orchids) and a propagation area for seed and cuttings. I mapped temps within the greenhouse using remote thermometers last winter to see what the micro-climates were and have tried to take advantage of differences in minimum temp within the greenhouse. I don't have anything special for heat retention, though I do have a row of short (15-20') pine trees along the north side of the GH that works as a wind break.

well i don't know much about greenhouses but i will say this. a man i know that sells at the market has a 20x 40 greenhouse and he got a small wood burning furnace and fires it with fallen limbs. I am sure he got the furnace for a bag of hog feed or some sort of deal he worked out but i have seen em going for about 200 in the local stores. might be an option for some of you who have a similar sized greenhouse and want to use a free fuel source to heat it, and chopping up wood is good cardio

11 x 16' home-attached all-glass greenhouse, wrapped in a solar pool cover with a propane direct-vent heater and a small supplemental electric heater....and even it midnight it's a balmy 62F...and on a sunny day we easily get into the 80s. We love it and the cost so far isn't too bad even with consistent teens outside. So yes were crazy.

am in cetral texas and just finished a structure made of 5 windows(3 52x 32 and 232x35) full sunlight in daytime. temp is a toasty 102 F question is will an inner tube from car or truck filled with water prevent too much of drop (below freezing) in zone 8 coldest is in teens for day or two at a time

qrpr--I'm in north-central ohio.
Up till this year, I have only grown from seeds (except for a few succulents). Seemed a better way to control pests.
This year I am trying some cuttings. I'll let you know if that's a thumbs up or down.

@johngreenhand - We tried a 60-gallon black plastic water barrel last winter and foudn that it did very little. By the middle of the night when we needed heat, it was long gone out of the water. In the end we felt like it actually cooled the greenhouse more than heated it so we decided it wasn't worth the space it took up. You mileage may vary but it didn't work for us.

@lily51 - Pests still manage to find their way into our greenhouse and since we allow our cats to play in the greenhouse, pests can be difficult to get rid of so the greenhouses are not immune unfortunately.

I'm having a bit of a time right now controlling the temperature inside the greenhouse. I've covered and sealed all the powered shutters 'cause they really let in the cold air. But, with a sunny day, i've hit 94 according to the data logger.

I figure I'll have to remove the covering sometime in mid to end of February as the days will be getting longer and the sun up higher in the horizon.

After several panic-weeks in late fall and early spring (with high temp spikes) we gave in and cut a small flap in our solar pool cover that allows one of the roof vents to open a tiny bit. We weighted the flap with wood strips to keep it down when the vents are closed. This has worked great. We noticeable no temp loss (or fuel increase) on normal days and no high-heat peaks on hot days. We tried circulation fans (don;t cool much) and misting systems (add too much trapped humidity) but in the end the vent needed to open.

Crazy as they get! I'm in Columbus, Oh and heating mine to a minimum of 68...all due to the type of plants I have growing. My greenhouse has double pane, insulated glass and the structure has thermal breaks. Holds heat great and will not melt snow off the roof glass. Yeah...gas bill is a bit higher but not as bad as we first expected. I keep the GH much warmer than the inside of the home!

Count me in. I'm as crazy as they get and add to that a Compost Wacko! My gh is over 45 years old, all glass, attached to house on south side and with a sliding glass & screened door, a temp controlled lifting vent across the top and a louvered window at each end. Plenty of ventilation in summer and in winter a ventless natural gas heater. I winter grow geraniums, camellia, Kalanchoes, petunias, etc. and overwinter the patio pots under the benches. The cannas, tubers, etc. go under the bench where it's closed off, cool and dark. I have rarely had the gas heater above one notch above Low and temps in there last night (3 degrees F. above outside for SW Misouri - not usual) were around 58 degrees. Some nights I use a small supplemental electric 1500 watt heater blowing in the cool end, and have arranged for the electric dryer vent to vent in the gh in the winter, useful to put warm air in there in the cold evenings.

From this forum, I got the idea of using water-filled green liter-sized bottles next to the glass on the south side and they seem to help hold the solar heat. I also put up 1" thick foam panels next to the vertical glass in the evenings, and I know how much that helps. The panels store under the bench in the daytime. The vertical glass all around has Charlie's large bubble plastic now and I keep it on the south side year around. Only Kalanchoes, Aloes, and various sedums are in there in the hot summer.

Yes, it's a little expensive for the gas. And I can't say I don't get up a couple times on extremely cold nights and go out there to see if all's well. I worry about a high limb coming through the top glass (it did last year for the first time) but/and there are few things so joyful as a greenhouse. With expense and risks, I still would have it. Here are three photos.
Sunny

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What a beautiful greenhouse you have. Heating is the worst thing for me. We have had such a cold winter down here in Florids. Jusy not use to it or prepared enough. I runn 2 heaters at night and keep it up aroung 50. I have about 60 or 70 orchids hanging from the top.
I don't have an expensive GH. I have 3 of the 10X12 HFGH's.
I have 2 of the hooked together back to back so I could have doors on both ends. I needed more room so I just finished adding another 10X12 HFGH to that. This time I left a door inbetween the 2 greenhouses and the 3rd one.
Hubby says I'm greenhouse nuts. But it keeps me out of his hair.
I am starting seeds for the garden next and I also sell a few plants to make a little extra money.

We have modified our Cross Country Cape Cod twinwall this year to help with heating. First we lined the interior with bubble wrap (except the door - haven't figured a good way to cover it). Next, my handy DH modified an old woodstove adding a water jacket & interior water pipes. The stove is in a small wooden shed outside directly behind the north wall of the GH. We ran underground PVC to a sunken 55 gal drum of water inside the greenhouse (buried a little extra PVC pipe in our 4" pea gravel flooring). He then rigged up an old car radiator with a box fan behind it to run the warm water through as a heat exchanger. Has been great so far if you don't mind feeding the fire. It will hold for 8 to 10 hours. It's miserably cold here & we've been able to maintin around 39 to 49 degrees at night & much warmer during the day. We also have a 220 contractor's heater to for backup should the temp drop too low. This week, our night temps have been in the single digits to mid teens outside. Hopefully we'll warm up soon.

Krayers, That's an interesting concept.

there was a guy just up the street from me that had two very large hoop GH that he ran from late february to mother's day. All heated by wood. He of course sold the plants, but he told me that from feb on he never got a full nights sleep, as he was always getting up to feed the fires. These houses were massive, a good 60' wife and 200 feet long.

He told me if it weren't for the free or nearly free wood, he couldn't afford to heat the houses.

Qrper, We aren't heating nearly that large a space. We also live on a 2 acre wooded lot and lose an average of 1 to 2 trees per year, so we have a large supply of wood. Figured we might as well use it as give it away to someone else. I've been loading the stove at around 9:30 to 10:00 p.m. and again at around 7:00 to 7:30 a.m. with plenty of coals left. Leave it while at work & reload around 5:30 in the aftnoon. With the cold winter here in NW Tenn, it's been a real blessing. When the weather warms up a good bit, we'll probably not keep the fire going continually, but it's really not been a problem so far.

This being my first winter, I thought the rain barrels would help. I hauled them out today and now there are 55 gallon ice cubes in my yard! I am going to have a small woodburning stove installed to use in the spring when nights are still cold. I use a small kerosene heater at times, but kerosene has gone up 30% in a month. Oh, and only one barrel is returning the greenhouse.

Sunnyside, beautiful greenhouse.

One problem with using water as a heat sink is that water is a heat sink.I don't recall right off the tip of my head, but water will hold and release a huge amount of BTUs

In theory, it works great, sun heats up the water during the day and the water radiates the heat at night. Life is good!

But, if you don't have another sunny day to repeat the process, that water in the barrels will then sink whatever heat they can find. Including whatever heat maybe coming from a small heater running.

I gets overly complex, the law of thermodynamics, but in a nutshell, heat will be drawn to cold.

Now, don't get me wrong, having a large heat sink being water, rocks, or even a dark brick floor will store heat and release it.

It takes a lot of water and lot of sun to keep the system working.

I have a 12'Wx50'Lx12'H polly greenhouse, the first year it cost $1500 to heat all winter. The following year I installed four 1000 gallon poly tanks buried 5' deep attached to a circulating system designed for greenhouses. It operates at temperatures below 60f and above 80f. The past 5 years it has paid for itself in heating expenses. It now costs about $350 to heat all winter.

Outside low last night -16F
Inside the Greenhouse low last night: 56F

Fuzzymoto, that's called COLD. Kudos to you for 56 degrees F in there -- whatever you're doing, keep doing it, for Spring will be here and that minus 16 will just be a bad dream.
Sunny

Our GH is home attached so the north wall is our insulated house. We're wrapped in a solar pool cover (huge help) and we have a direct vent propane heater, curculation fans and a small electric heater (just in case)....and so far the propane bill has been incredibly low.

I've had a 220 electric heater in my greenhouse for the past 8 years. I also have a large circulating fan to keep the air flowing throughout the greenhouse.

I have a 20x23 GH I keep at ~54F most of the winter. After trying no less than 3 different techniques for winterizing, finally arrived at 1" of reflective foamboard insulation on the north wall and a layer of 4mil poly hung all around the rest of the inside. Presently I have blooms on lychee, orchids, carambola.

Water is disappointing unless you can tolerate your GH down to just at freezing. Most of us won't do that, and we find that the water just wastes space.

I'm not in a very cold zone like many of you, but I keep my 10x12 gh heated all winter too, with two electric heaters. Reflective foam board insulation on the north wall too. Minimum 45F keeps my wimpiest cacti and succulents happy. A few Mammillarias are blooming away.

We may have a low of 6F tomorrow night. The record for the date is 11F here, so I'm not happy (stand to lose quite a few plants in the ground, even with covers.) If I could heat the yard AND the greenhouse, I probably would! Yard is a crazy quilt of old sheets, towels, and blankets tonight. You all keep warm.

I am up to my eye balls in ice right now. Got kerosene ready, ice storm in my back yard, so going to be one heck of a week.

Hope everything holds together.

Mike

Mudhouse

Didnt knew it got that cold in nm.

That's chilly no matter where you live.

Mike, it got even worse (a record for Las Cruces.) El Paso Electric Co lost two generators early Wed so we're still having rolling brownouts. Fortunately for my greenhouse they didn't cut our power after 10PM last night. At 2:30AM the Wunderground website showed -6.4F for my neighborhood. By dawn my two 1500 watt heaters running full out were still able to hold my GH at 37F. I keep it at 45F so expected some damage. Was able to free the frozen-shut sliding doors this morning, no losses! I had loaded about 15 of my largest succulents into the living room the day before, thank goodness since some of them would not have taken 37F. When I calculated my heat need for this 10x12 polycarb GH I did not consider -6F degrees!

Dodged a bullet as long as we don't lose major power tonight. They are predicting 4F for a low. That seems like a heat wave after last night. We only got 4" of snow with this, and are not pros at handling these temps like most of you. I slept with my sneakers, jeans, and long johns on last night, ready to leap into action to save what plants I could!

Who knew having a greenhouse in southern NM could be so hair-raising. I hope you are all doing OK and staying safe and warm.
Sheri

Shoot, wonder why I'm showing zone 10 in the above post, I keep telling it zone 8 (although it feels like even less for the last 48 hours.) I'll do it right this time.

I'm just starting in the greenhouse world but trying to keep cost down hasn't worked out so far. This year was my first winter and I don't have anything important in there just a few potted plants that I didn't want to freeze solid. I have a homemade hoophouse 12'x30' quite the space to keep warm when empty. I did get double poly with the inflation kit, and also have a small (1500 watt)elec heater and a box fan for circulation. I did recently put in an air pressure switch and a small peice of plastic as a check valve on my inflation kit which made a huge difference because it kept over-inflating and allowing air in. I'm hoping next winter to be able to keep it warm enough to actually grow something right now it stay about 15oF above outside temps at night and is costing me bout $100 a month. Working on some thermal mass and need to find a mafia arborist to go cut down my neighbors pines blocking the sun lol.

If it's costing that much to heat, you should fill it up.

It cost just as much to best air as it dies to heat plants.

Fill 'er up with something.