Anyone here Zone 5 & Below have a Greenhouse?

belle_michele(zone4Minnesota)January 4, 2005

Greetings All...

Is there anyone here in Zone 5 and below that has a 'hobby' greenhouse?

I got a HF greenhouse at the end of October-I wasn't able to set it up yet (slated for April, depending on weather)...and am now wondering if the idea of having a 'hobby greenhouse' isn't totally INSANE for someone in zone 5 and below...especially after reading all the posts about problems/expense heating greenhouses in zone 7 & 8 (areas that I've considered almost 'tropical'...).

While I realize there is no way I can keep it a balmy 70 degrees inside when it's minus 10 outside.... I would like to be able to keep it at about 38 or 40 degrees (without having the heating cost exceed that of heating my house).

I'm starting to think the only way I could keep the inside of the greenhouse above freezing during the winter in this zone is to set it up in the middle of my living room...

ANY help/advice would be GREATLY appreciated!

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belle_michele, that's funny but sensible. LOL

    Bookmark   January 4, 2005 at 3:27PM
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eleanor_rigby(z5 OH)

Hi Michelle,

I live in zone 5. I have a hobby greenhouse that is 12X20. I don't know anything about an HF greenhouse, because my husband and I designed and built our own (with the help of a very understanding contractor). I will describe mine for you. It is covered with Lexan Thermoclear. Then, we stapled bubble insulation from Charley's Greenhouse Supply inside on the beams. This runs all the way down to the floor on all sides. In the winter, I cover the vents and the door with bubble insulation too. I heat with natural gas using a greenhouse heater. My budgeted gas bill for home and greenhouse is $110 per month right now. I do expect it to rise some because the gas company was granted the right to increase its rates. I keep the temperature at about 58 degrees at night. Many days, the sun warms it up to the 70's. If it is a cloudy day, the furnace keeps it warm. I know that not everyone can afford to do this, but my philosophy is this: I don't buy fancy cars, I don't wear expensive clothes, and I drink cheap white wine. I work for a living, so I choose to spend my money heating my greenhouse. Of course, you need to make decisions within your own budget. What do you want to spend your discretionary income on?


    Bookmark   January 4, 2005 at 6:23PM
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I use my green house to grow veggies. both for eating and the starts for my garden. I think that just like regular gardening season you have to garden within the limits of your green house. If it is too cold in there for tomatoes grow lettuce. If it is too cold for lettuce grow a little some thing in your house window sill. I have found it wonder full for extending my normal growing season. Also I know I could not have so many plants for my garden If I had to buy all of them.

    Bookmark   January 4, 2005 at 9:07PM
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sandy0225(z5 Indiana)

I love my greenhouse. I have an old (from the 60's) Janco glass to ground greenhouse. I installed bubble wrap this year on the glass to help with the heating bills. It's still expensive, but I keep it heated to 50 degrees for my bananas. We've made cutbacks in other areas to compensate for the expense. I also sell plants in the spring to help pay for my utility bills. I did manage to break even last year by selling tomato and pepper plants and tropicals. So I plan to do that again this year. As long as I can break even or even help on the bills in this way, I figure this hobby becomes a little cheaper. Don't be too discouraged!

    Bookmark   January 5, 2005 at 8:56AM
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sta4(z5 WI)

I have a HF I set up 2 years ago. It costs me $30 a month (electric heater) to keep it 10-15 degrees warmer (Sept-Oct and April-May) than the outside temp. This extends my growing season by 4 months for my tropical bonsai. Then my temperate trees are moved in and I don't heat it. You'll need auto vents and a min/max therometer to monitor the temps. The first winter I kept nothing in the greenhouse so I could learn how it compared to outside temps. It stayed about 5 degrees warmer at night but if its a cloudy day it can hold onto the cold and remain colder than the outside temps for most of the day. If its sunny I can have a rise in temp of 30 degrees- but most of that will be lost by 8 PM. Based on your temp you mention I guess you want to overwinter plants that are a few zones higher than 5. You might want to consider soil cables to help with the very bitterly cold spells we can have. They don't cost much and can add extra protection for little $. Good luck.

    Bookmark   January 5, 2005 at 10:48AM
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poppa(z5 MA)

Hi Belle. I'm in Z5...

I don't have a green house at my new place, but at my last house (about 8 year ago) i built a garden shed with an attached lean-to greenhouse. I used it for 3 years before i sold the house. The greenhouse was about 12 x 8 and made from storm windows that i cut the glass down to fit into a frame i made of PT 2 x 4s. It was partially sunk into the ground (~2 feet, mostly because the roofline of the GH followed the Shed roofline. By time the GH roof got 8 feet out, it was only 4 ft abouve the ground. I dug down so i could have a 6' wall and then put in a raised bed inside that brought the bed up to the original soil level. I think an added benefit was it reduced the exposed walls and made it that much more less prone to heat loss, though i don't imagine the walls are the place of greatest loss.

In the Winter, i used to staple a layer of poly to the inside so i had a dead air space of ~4". I grew tomatoes and cukes into late december. Jan/ feb was greens and radishes. I used no heat. Daytime temps would hit the high 90's on a sunny day. I didn't bother to vent unless it was too hot to work in there in shorts and shirtless. I only had one time when the greens froze when we had a week that stayed below zero, but enough survived to keep us in salad all winter.

So it depends on what you want to grow. Some things take more cold that we realize. I keep several citrus trees in the (unheated) garage now and they do ok. I put them there last year due to a spider mite infestation and they lost all their leaves but regrew fine this year. Now that i know they can take a week of temps in the teens, i am keeping them there from now on. So far we have only had a couple of days in the single digits, but they have not loast their leaves, nor show any freeze damage. I am fairly sure the leaf drop was due to the spider mites and not the cold.

Bottom line: If your going to put your orchids out in the GH, you're going to have to heat it. Grow cold hardy plants and you should be able to do fairly well.

Keep in mind that my lean-to had reduced surface area because of the short walls and, in being a lean to, had an insulated back wall and only one roof, all pitched towards the sun.

Good luck!

I hope to be building a larger greenhouse ~20 x 40 this sumer, and i also plan to keep heating in that one to a minimum. Some secrets in the works that i'll keep to myself for the time being (unless they work!).

    Bookmark   January 5, 2005 at 12:19PM
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I start in Mars -perennial seedling -no problem -just a cheap fan ..keeps temp over +5 c

    Bookmark   January 6, 2005 at 8:22AM
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I have a greenhouse 10 by 12. I just bought a radiant heater from Lee Valley- 69.00 canadian plus taxes. It is supposed to heat 200 sq. feet for 15 cents an hour in electricity. I am not putting it in the greenhouse until the first of April. I know that will be sufficient heat for then. I had an oil heater but oil is expensive in this part of Canada so decided to try the radiant heat. Hopefully it will work out fine.

    Bookmark   January 6, 2005 at 11:30AM
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Thank YOU all for the feedback on greenhouses in the frozen wasteland!

I must admit, I suffer from a BAD case of 'ZONE-Envy'.... I want to LIVE in zone 5, 6 or 7! Zone 4 (it was below zero today, with windchills in the -10's) is MISERABLE..a person HAS to be INSANE to live in this kind of God-foresaken climate...*feeling VERY sorry for myself right now, as if you couldn't tell, eh?*

My goal is get my little greenhouse set up to be heated next winter, hopefully not costing over $50 a month to heat (this counting on energy costs on doubling from what they are now). I have no life except my plants/garden (friends/family consider it more of an addiction) so I am willing to devote what little expendable (ha-ha!) income I have toward my plants... All I want to do is keep it enough above freezing to overwinter some of my larger potted trees (mainly figs) and extend the growing season for the same plants.

I have potted bananas, lemon and lime trees that I'm used to hauling in and out of the house as weather/season dictates-but my figs need a certain amount of dormancy and my (two-car) garage has so many 'over-wintering' figs in there that I can't squeeze my car in at all..(figs and bananas are my top two addictions!). Some of the figs that need a 'longer' season I would really like to overwinter in the greenhouse and extend the growing season for....

I am going to looking into the soil heating cables...I know a friend of mine suggested I look into the cables you put on the roof to prevent ice dam formation... I'm planning on also using the 'pool' cover I've seen discussed on this forum as additional insulation and possibly a layer of poly or bubble wrap inside, as well. And I know with the seemingly endless (and I do mean ENDLESS) dark, overcast days, I will need to have a few florescent lights in there as well and at least one small, electrical heater.

I have a vent and fan kit that will be installed this spring.

Again, I am looking for 'above' freezing...not 'tropical'...(okay, if I could get tropical without having to sell a kidney to pay for the heating I would, but in the meantime, I will settle for 'above freezing').

I spend my evenings reading up on or contemplating ways of keeping the greenhouse 'unfrozen' weekends spent haunting DIY stores in search of alternatives or possible ways to insulate and/or heat the greenhouse/soil...

All said and done, a friend of mine has said it might actually be easier and cheaper for me to just move to Florida!

The ultimate irony is that the only thing that has kept me from moving is my much time/effort/emotions invested in it and it's all finally coming together.

Again, THANK YOU all for the feedback/tips/etc.,... I feel a little more relieved after my inital panic that it is 'do-able' to have a small greenhouse here (despite the fact friends/family think I am CRAZY and are now past talking about 'intervention' and now hinting about 'institutionalizing')..just will take a bit of experimentation, trial and error and creativity....

    Bookmark   January 6, 2005 at 2:37PM
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I have both a heated 10 x 16 sunroom and an 8 x 16' greenhouse plus a 8 x 24 heated room in my garage here in Zone 5. All my utilities are combined on one billing so it's difficult to determine just what it costs me for heat & electricity.

On the other hand what is it worth to be able to enjoy beautiful flowers 12 months out of the year and to be able to fill your flower beds with plants each spring. To walk into that sunroom or greenhouse on a cold winter day and enjoy the growing plants & flowers is priceless. Just look at the link below and put a price on it for me!!

Marv - Montezuma, IA

Here is a link that might be useful: Greenhouse & Flowers

    Bookmark   January 8, 2005 at 6:49AM
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ctufts(z4 Maine)

I live in Zone 4 also..Maine. Brrrr !!!. I heat my greenhouses at the end of February with Oil. I have 2 17x48'greenhouses. I have an oil furnace. I used to heat in January, but it costs too much. I have a full tank of oil in there right now. Our temps haven't really been all that bad yet, BUT

    Bookmark   January 8, 2005 at 7:57AM
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Hi Belle...this is kind of off topic...but how do yor citrus plants handle the transition to the house every year?

    Bookmark   January 8, 2005 at 6:50PM
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Glenie1(z4 NY)

I live in Zone 4, Central New York. My husband and great friends helped me put my new greenhouse up this past summer. It is a kit from Sunglo and perfect for my skills. Even though my husband does not agree with me. I have been heating it since the end of October. I use propane on a 10X12 and just called for a fill up. It is costing me about $60.00 a month. It had not been really cold yet. I am just playing with it now. Will be starting seeds soon.

    Bookmark   January 8, 2005 at 7:37PM
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Just remember if you use electricity to heat your greenhouse even gas of some sort must have an alarm system. If it's -10 at 3 a.m. your plants will be dead by 3:30. H.F. greenhouses are not made for cold climates so expect high heating costs. 4mm is not insulating anything so you'll be paying $50 a month during the winter. Close it down late Oct. and use lites in the basement.

    Bookmark   January 11, 2005 at 1:12PM
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Susan-I actually start moving my citrus into the garage at night and moving them back out in the morning (a friend made flat 'plant' carts for me) at the beginning of September. Then, depending on the weather, they are moved inside full time mid to late September.

I am by no means an expert and welcome ANY/ALL thoughts/advice/tips, etc...

It's been a learning experience...the first year I had a problem with whitefly (imported by a 'gift plant')...the whole humidity (and problems w/fungas and fungas gnats) versus complete descicatition...and of course spider mites.

I'm on year three now and this is my 'current' routine:

*Neem spray for all the creepy crawlies.
*Wilt-Pruf to keep the foliage from drying out too much from the dry heat inside.
*Use sunlight from windows supplimented by flourescent (one cool, one warm bulb) lighting on a timer for 16 hours a day.
*Keep the plants on trays filled with pea gravel, keep the gravel wet to provide humidity.
*Keep an ossilating fan on the plants to keep air moving & discourage spider mites.
*Try to find the perfect balance (this is a challenge) between overwatering (rot/fungus) and underwatering (death/drying up).
*Minimal fertilization.
*Keep my fingers crossed and pray like mad....

My dwarf lemons and limes obviously don't flourish like they do outside in the spring/summer/early fall...but at least they look reasonably healthy...growth slows down when I have them inside.

Come spring I either completely re-pot them or 'partially' re-pot them...

If you have any ideas or suggestions that work for you I'd LOVE to hear them!

    Bookmark   January 11, 2005 at 2:34PM
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watergal(z6/7 Westminster, MD)

belle michelle, are you using Wiltpruf on just citrus or on other types of plants too? I use it outdoors on shrubs that are pushing the zone, but I never thought of using it indoors. Interesting idea!

I do grow lights indoors instead of a greenhouse because of the whole cost of heating issue. I'd still rather have a greenhouse, but this is cheaper and I don't have to worry about it collapsing in the snow.

    Bookmark   January 12, 2005 at 3:09PM
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Belle Michelle, I am learning too. I had a lot of leaf drop this year. I use a humidifier, but maybe I will also try Wilt-proof. I have them under a metal halide light. I was saying on another thread, that previously I had leaf drop when I first brought them inside, but this time I didn't get that until 2 1/2 months later or so.

    Bookmark   January 14, 2005 at 1:50PM
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sandy0225(z5 Indiana)

I had a metal halide light in the basement two years ago and it cost me nearly as much as my greenhouse. And I was constantly scared about all the moisture I was putting in my house by all the watering, etc. I had a terrible time with spider mites, because I tried to keep it drier and was afraid to spray the pesticides in the basement.
I'd rather pay the $ for the greenhouse, just my 2 cents worth!

    Bookmark   January 16, 2005 at 4:53PM
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I use WILT-PRUF on all my overwintering plants (except my banana's)...I think it helps keep them from drying out...
While this year I don't have *fingers crossed* a spider mite problem I am starting to have problems with fungus gnats...I just ordered some Knock-out and hope that takes care of the problem.
I don't want to go the halide light route-for some reason I'm leery of them...I'm hoping I can find a way to keep my HF greenhouse above freezing over winter without going broke...

    Bookmark   January 18, 2005 at 2:32PM
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hairmetal4ever(Z7 MD)

I live in NE Ohio which is either a cold zone 6 or a warm 5, depending on who you ask. Our biggest problem is that from Nov. to March we get about 25% of possible sunshine-lots of clouds. Have you found that sun-loving plants need a light supplement like a HPS sodium light or has natural light been sufficient??

    Bookmark   March 22, 2005 at 6:58PM
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I live in NY zone 5 and have a HF. The temps here can go as low as -5. I started my greenhouse on March 1st. I bubble wrap the roof and put in two walmart heater hooked up to a thermostat with a nightlight plugged into the same socket, when the heaters go on the night light goes on. I have a wireless therm., one in the house and one in the greenhouse so I can watch the temp in the greenhouse without going out in the cold. I can see the night light from the house so I know when the heaters are running. I have been able to keep the gh temp at 57 degees at night when the temp outside was 5 degrees. Mind you the electric in my town is very cheap but it is costing me about $20.00 to heat it a month. In the day time it gets in the 90s when the sun is shining and the heaters go on about 2 hours after the sun goes down and they go on and off thoughout the night which saves on electricty.I could keep it warmer with this system if I turned up the thermostat but 57 degrees has been working well for my seed flats. My gh is my home away from and I'm growing enough for friends and relatives and in return they are helping out with things I need, barter system. I gladly would give up the dinners out and such for my greenhouse!

    Bookmark   March 22, 2005 at 10:14PM
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erlyberd(Z5 CT)

Perhaps you could build a passive solar unit depending on what your needs are? Some of the properly designed units will have lows of only 40 degrees but may need supplimental heating at times. A pit greenhouse may work too.

    Bookmark   March 23, 2005 at 11:47AM
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poppa(z5 MA)

Just an update since some people here were looking to overwinter citrus.

AT the end of march, my two 4' citrus trees are doing fine in the unheated (but insulated) garage. One lost some leaves on the lowest braches, the other lost none. I now believe that most of the leaf drop last years was because i tended to ignore them and probably did not water them as much as they needed. We had several weeks of below zero weather and they came through fine, even when the kids left the garage door open for several hours when the temps were in the 20's. I have a tender perennial in a pot and it lost all it's foliage but the trees lost very little. It too is greening up.

Both trees now have a good 3" of new growth. I used nothing like wiltpruf. I did spray with safer soap for mites, let them sit for an hour then rinsed them off before they were put inside for the winter.

If i remember, i'll try to post a photo later tonight.


    Bookmark   March 23, 2005 at 12:23PM
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sterling3(z4 NY)

I live in central NY, they say its zone 5, but its really 4.

I have a glass 8 by 12 foot gh. I don't use it in the winter as it is free standing and would cost too much to heat. I do use it to grow up my seedlings. I put them in around April 8th, and have to heat it at night for about 2 weeks, until it warms up enough.

I then put those plants outside, and put my orchids in it.

When I heat it those first few weeks in April, I go through a 20 lb. propane tank every 3 days or so. After that, it mostly stays just on the pilot light and that seems to be enough for another few days. At that point, I turn it off during the day.

I also have two, 50 gal. water barrels for solar heat and another couple of 30 gal. containers.

It has a cement paver floor that helps hold some heat.

My goal is to move it and attach it to the house. Then I would just get a 100 gal. propane tank for heat and keep my orchids in it all the time. I would have to raise it up 3 feet to match a door to the house, so I would gain even more room.


    Bookmark   March 24, 2005 at 2:54PM
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hairmetal4ever(Z7 MD)

I am borderline zone 5/6. Doing the math for the last 30 years, taking the lowest temp each winter and averaging it out, I got -8.3 degrees F which is a cold 6 or a warm zone 5 to be safe. Anyway, I am trying to build a greenhouse that I can keep in the 60s day and 40s nights. I figured if I use twin wall polycarbonate panels I can keep heating costs reasonable.

    Bookmark   March 24, 2005 at 4:40PM
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Hairmetal-what are polycarbonate panels?

Poppa, I like the idea of your greenhouse at the home you sold. Sounds like something I would like to under take. Thanks for all the info everyone.! Jacquelyn

    Bookmark   March 24, 2005 at 5:12PM
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If you are going to run the greenhouse in the "dead" of winter in Minnesota you will also need supplemental lighting..(metal Halide would be best) because with the 8-9 hrs of sunlite in Dec and Jan. you will not grow anything but moss maybe lettuce. So you will end up paying for heating the H. F. greenhouse (not made for winters ) and the electricity for the lites. You may as well do it in your basement. A few plants will not raise the humidity that much...add a fan.

    Bookmark   March 27, 2005 at 9:06AM
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From what I've heard everyone is paying for the fossil fuels instead of covering the crop. As a rule of thumb you can gain one Zone for each layer of cover. So here is the solution: Build a larger initial house for greater thermal mass. Then set up hoops within the house using a canopy frame. Cover that with 3o wt Remay fabric. Plant your greens, then cover with low tunnels to hold the heat around them. You will have greens year round in Zone 5. actually I am harvesting spinach, tat soi,and arugula now without the internal covering but a 30'X96' provides a lot of buffer. When you contemplate what to plant, think spinach first.

    Bookmark   March 28, 2005 at 4:33PM
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vegomatic(z5 BHSD)

I did the gh-in-a-gh trick with great results too. A simple frame or even wires strung from the walls to hang plastic over. We put strings of xmas lights under the tents and added blankets on top at night if needed. No heat in the gh itself. It was easy to keep it at least 20F warmer under the covers.


    Bookmark   March 31, 2005 at 12:47AM
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hairmetal4ever(Z7 MD)

A good triple-wall polycarb house would be reasonable to heat, even with the supplemental light you'd have to have (which would cost more than the heat around here). If I go with an 8mm triple-wall polycarbonate GH, I figure I can get away with 18000 BTU's to keep it at 50 or above, which might cost me $30 a month-but the electricity I'd need to power 3200 watts worth of HID lights would cost me $80. That's what I'd need to keep acceptable light levels. Even if the short days weren't an issue, the fact is our winters are so dark, that with the 25% light reduction inside a GH's walls I wouldn't be able to grow anything but pothos and Diffenbachia inside without some supplemental light from Nov. thru March.

    Bookmark   March 31, 2005 at 11:15AM
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Drew_N_Corinn(Utah 6B)

I am sort of resurrecting this thread but I think I am gonna buy a sunglo as triple wall polycarb is too expensive and the sunglo system has about 1.5 inched between the walls. Anyone have any additional experience I should hear aboutwith them?


    Bookmark   May 26, 2005 at 1:49PM
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