Since this is a forum with mostly Americans we wouldn't know what is most economical in your country. Perhaps you can contact a University or power company and inquire.

Hi beth47,

Some posters on here can probably give you great advice on how to use your greenhouse to extend the growing season without supplimental heat or electricity but.....

I say but, the flower thing is really going to restrict things. Flowers tend to flower when the day length is right.

Not knowing anything about your climate, I would suggest you use your hoophouse to start both flowers and food crops. Move the food seedlings out as soon as you can to make room for flowers, move food crops back in when the flower season is over.

The flower thing is restricting you.

Dear Chris and Greenhouser -

Thanks for your follow-ups on this question - yes, I am aware that flowers restrict us - most of our families have small greenhouses for food production, we are just trying to extend their ability to produce an income with the flowers. What we are trying to do is heat the greenhouse without using methods that are costly - so electricity is out - any ideas on solar methods/storage that might help? Our climate is very similar to Northeast Washington, Northwest Montana - cold in winter (can get to -10C), and very warm in the summer +30C) and the spring can be very variable... So as to what is most economical - what I am REALLY looking for is alternative methods to electricity and complicated heating and piping methods... So any advice would be greatly appreciated.

Beth47,

Hey, I am not sure we can provide you an answer. There are several solar type things you can do by putting lots of water in the greenhouse but in order for that to work, you need good hot days to heat the water, so it will give it back at night. This takes a lot of room.

Your best might be a fire place of some sort. Here in America and this forum, most of us use the conveniences that are available to us. There are a few that have wood stoves, or do not grow during the winter time.

I like your idea, but not sure when you need the heat with what you want to grow.

There is not a sure fire way to get free heat unless you make a fire. If there was something great and wonderful out there, we would all be doing it. The solar stuff, is great on paper but can cost an arm and a leg. The water bottles might help you not freeze it but it will take alot of water.

The best advice is probably your fire place and a fan of some type.

If you come up with something, let us know. Good luck.

Rob

You can get additional heat by adding a second layer or plastic on your tunnel and cyou can reate a bubble between the town without electricity. This may be a challenge if your tunnel is already built, but here is the basic idea that I have seen at work on Amish farms around here:

The first layer of plastic is laid on top of the hoops and secured. Then, t-tape or rope is tied to the base board on one side of the tunne., between each hoop, and strung over the structure to the other side's base board. When the rope/tape is pulled tight and secured to each side's base board, it pulls the plastic down in between the hoops. When a second layer is added, bubbles are created that add insulation and an additional couple of degrees. This cuts out the need for a fan, and electricity use, but only gains you a few degrees. Of course it still gets cold at night, but not as cold.

Thanks, Pillar, for the suggestion - any idea where I can find some directions to do what you are suggesting? It sounds simple enough - but diagrams would be helpful when working with non-english speakers...and just to clarify, we are definitely not trying to heat the greenhouse in the winter - just trying to warm things up a bit earlier in the spring if we can - give our people a bit of a head start in growing and (hopefully) selling...

Hi Beth47
I think Pillar`s suggestion is the most economical.

The air spaces between the hoops are good but at the steel hoops themselves you`ll have 2 layers of poly with a zero airgap. This makes a good thermal bridge from the interior to the exterior, a direct path for heatloss.

Insulating the poly from the steel hoops will fix it.

At the expense of some light, small tunnel coverings over the beds within the hoophouse would gain still another couple of degrees, but this is only a variation of Pilar's idea. Because you already heat with wood, if you have ventilation, your initial idea of adding a stove sounds like it is the most economical, especially if you're only lighting it during the colder nights. A fan would be nice to keep the warm air down from the roof. The flower plants could grow a little early while frost is outside but above freezing inside, so that you'd have an earlier harvest of flowers than usual.
~tom

Hi Beth47, We are currently researching options for heating a greenhouse. What about keeping animals in the structure. www.solviva.com has some info. Animals produce the heat at night. I think solviva used chickens and rabbits. Good luck.

I might suggest digging down and insulating with earth. Allow the light to come in from above and use dirt as a heat retainer. Perhaps three feet down would give some protection. Then, thermal mass - like water - to retain heat. You could add heat with compost piles inside the structures. The heat of compost can be significant. If you have fresh horse/cow dung to add, that becomes a greeat starting source. The resulting compost os also a wonderful soil amendment for better crops. Hay bales make good insulators as well.

From a solar perspective, you can make water heaters by placing black pipe (platic or metal) inside two windows. Let the light hit the pipe and it will heat the water. Convection would draw the warmer water to the cooler water and heat the larger mass without mechanicl or electrical adds.

Try www.otherpower.com for some great examples of harvesting energy from the earth, water and sky.

Good thread for this time of year. We have about another four weeks to work this problem through before beth47 and her team need to get things sorted out and in action.

To do this right the "experts" at the Greenhouse and Garden Structures forum need a lot more information. (I was laughing when I typed that BTW)

O.K. I will start with a few questions, I hope others will ask some too and then we can start a thread on the best way to solve a problem. just like we did when we expanded the FAQ section.

1, What flowers are you trying to grow?

2, (stupid question after you answer #1 but) Are you growing your flowers from seed? Are they annuals?

3, Are you growing them in pots or direct in the ground.

4, Have you access to cheap (big) containers that can hold water? (this also fits in with what you told us so far ""we have running water on site (but it is subject to dry spells)""

5, Is there someone there all the time that can remove covers, put on covers, stoke a fire 24hrs a day?

6, Have you access to electricity within the distance it takes someone to carry a car battery without suffering a heart attack? (my double poly inflation blower is 12 volt. a small battery lasts 72+ hours between recharges)

The basics we almost all agree on is you can start plants a month before your last frost date, and continue to keep things alive up to about 6-8 weeks after the first killing frost in the fall with a poly hoophouse and some trickery.

As to the plants/flowers themselves I will leave the experts to advise you. I can grow them and prevent them freezing to death but as to the timing of blooming and the day/night length requirements I will leave that to others. I got ripped a new one because I didn't understand it.

Oh!!

7, Have you access to scrap metal and does any one in the community weld? If so you are going to love this one!

:)

Good thread for this time of year. We have about another four weeks to work this problem through before beth47 and her team need to get things sorted out and in action.
Thanks to all of you who are willing to help me on this  I am a biologist by training, (but an environmental biologist)  so know something about "biology" of plants (which makes me the "default expert" here, but never had to deal with anything like this before  Things warm up here a bit faster than they do in Idaho, so IÂd say we have until the end of Feb to get things sorted out  since it would take some time to get things in place (if "we" come up with some solutions)  One of the things we need to keep in mind, is that it gets proper hot here too  so anything we do to the greenhouse to warm it up will have to be countered later in the summer (aaahhhh!!!)

To do this right the 'experts' at the Greenhouse and Garden Structures forum need a lot more information. (I was laughing when I typed that BTW)
· YouÂre all more expert than I am J

O.K. I will start with a few questions; I hope others will ask some too and then we can start a thread on the best way to solve a problem. just like we did when we expanded the FAQ section.

1, What flowers are you trying to grow?
· All annuals, mostly cut flowers, we also tried to grow flowers in pots for people to sell, but not much of a market for some reason  lots of market for cut flowers thoughÂand advice on easy, fast growing annuals with sturdy stems for cut market would also be good  know this is off topic here, but one of the problems we had last year was transport, which is done mostly on horse and cart, bicycle or on foot  which wreaked havoc on the flowersÂ

2, (stupid question after you answer #1 but) Are you growing your flowers from seed? Are they annuals?
· Annuals, from seeds  no direct inexpensive source for seedlings

3, Are you growing them in pots or direct in the ground.
· Start in pots, then after they are big enough and the weather is warm enough, we transfer them to gardensÂ

4, Have you access to cheap (big) containers that can hold water? (this also fits in with what you told us so far ''we have running water on site (but it is subject to dry spells)''
· Yes and no, drums exist in the country  but most of them are in use for something  nothing is wasted here  everything that can be reused is reused  so we have a few large containers, but they are also subject to being "borrowed"

5, Is there someone there all the time that can remove covers, put on covers, stoke a fire 24hrs a day?
· WeÂre a pretty small team of people, and we have about 10 people in the program, but keeping a fire going 24/7 when they have to keep fires going in their homes too is a real hardship for them last year, we covered and uncovered plants, and it worked pretty well, but we started plants in late April and that ran into the hottest part of the year, which burned the seedlings in the greenhouse  so if we could start seeds/seedlings a bit earlier, and get them out of the greenhouse a bit earlier, that would be REALLY helpful.

6, Have you access to electricity within the distance it takes someone to carry a car battery without suffering a heart attack? (my double poly inflation blower is 12 volt. a small battery lasts 72+ hours between recharges)
· Yes, and think that we could use something like that in the greenhouse.

The basics we almost all agree on is you can start plants a month before your last frost date, and continue to keep things alive up to about 6-8 weeks after the first killing frost in the fall with a poly hoophouse and some trickery.

As to the plants/flowers themselves I will leave the experts to advise you. I can grow them and prevent them freezing to death but as to the timing of blooming and the day/night length requirements I will leave that to others. I got ripped a new one because I didn't understand it.

Oh!!

7, Have you access to scrap metal and does any one in the community weld? If so you are going to love this one!
· Scrap metal is a very rare and precious commodity, and is one way for poor people to come into a bit of money, for example, a company tore down a building a few months ago, they left a lot of steel/scrap at the building site  by the end of a week  there was nothing left on site and someone abandoned a semi-truck in Checheci (a poor ghetto area where we work) and I watched them, over the course of about a month, dismantle the semi So, yes, we have people who know how to weld, but whether we can find scrap metal, depends.

ADDED FROM TWO OTHER POSTS:
I might suggest digging down and insulating with earth. Allow the light to come in from above and use dirt as a heat retainer. Perhaps three feet down would give some protection. Then, thermal mass - like water - to retain heat. You could add heat with compost piles inside the structures. The heat of compost can be significant. If you have fresh horse/cow dung to add, that becomes a great starting source. The resulting compost is also a wonderful soil amendment for better crops. Hay bales make good insulators as well.
· We donÂt have a floor on the greenhouse, so digging down might be an option, as is using composting  although, I think NetWorks tried composting a few years ago and the neighbors complained about the smell  most people here donÂt amend the soil (not sure whyÂmy Romanian doesnÂt run to those kind of conversations yet)

From a solar perspective, you can make water heaters by placing black pipe (plastic or metal) inside two windows. Let the light hit the pipe and it will heat the water. Convection would draw the warmer water to the cooler water and heat the larger mass without mechanical or electrical adds.
· Sounds like an interesting alternative  will look into it and thanks for the source below

Try www.otherpower.com for some great examples of harvesting energy from the earth, water and sky.

Hi Beth47, We are currently researching options for heating a greenhouse. What about keeping animals in the structure. www.solviva.com has some info. Animals produce the heat at night. I think solviva used chickens and rabbits. Good luck.
· Keeping animals in the greenhouse sounds like an interesting option, would take up a lot of room that could be used for growingÂbut will check out the site.

Beth: Digging down may be your best option. I've long been an advocate of pit greenhouses, having experienced one some years ago. One of our neighbors had one attached to his house, with an entrance from the basement and even with single pane glass, all it took to keep it quite warm all winter was a small cast iron, pot bellied wood stove, and we get very cold winters here.

If you have enough hands to do the digging and stones to use to line the walls, if you dug down to just below the frost line, the earth would do much to keep it warm in winter and cool in summer. Also, if they dug down another foot or so and laid in extra stones, drainage would never be a problem either.

Thnking back to our old neighbor's GH, the interior walls were brick, that he kept whitewashed. I recall how bright it was inside, in spite of it being at least 6 foot below ground level.

Thanks birdwidow, not sure we have enough hands to do that this year, but if things work out, we may start another greenhouse next year and modify the one we have too...and digging down may be an option -

What you all need to keep in mind (please) is that we are not sophisticated growers, and have no real experience in this - we are just trying to meet a need in the communities we work in and so any help/resource info that you can give us is greatly appreciated.

On the subject of 12v blowers, i use one of those too :)

To make the most of the battery and extend the life of the blower.. use a pressure differential switch, that way the blower operates for just a few hours a day instead of 24/7.

I guess you could build a good sized water tank using ferrocement for minimal cost, the chances of someone stealing it would be pretty slim :)
A reserve of water would be worth its weight in gold to your flowers if you have an extended dry spell.

Here are photos from greenhouses dug 6 feet into the ground, that rely only on solar heating to grow lemons. The greenhouses are in Tajikistan, latitude 39 deg.
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Thanks, cuestaroble, those are awesome photos - any chance you have plans for these?

And if there's anyone out there who wants to come work long hours, for no pay, with people who sometimes yell at you because you don't do what they want - but loves to make a difference, then contact me and we'll send you an application ;-)

The roof is a simple wooden truss structure, with a wire lattice attached, then polyethylene. It is somewhat wider than the planting area hole to keep out water. The straw on the top is pulled over the plastic at night to help retain heat. Other greenhouses in the area use rolled, compressed straw which is easier to cover/uncover, but more expensive. The hole is simply dug out in the ground and is not lined with any material. The size of your available plastic for the roof would determine the actual dimensions. The ones in the photos are 8 meters X 50 meters. The lemons are furrow irrigated and manure fertilized.

cuestable: Your photos seem to support my argument for pit GH's, which isn't much of a surprise, considering how many centuries they have been used to grow warm weather plants in cold countries- sans heaters, artifical lights or electric fans.

As for lining the pit: I admit that I never thought in terms of an unlined one, but our soil is far too hydric to allow it, so any pit GH's I've ever seen here have been brick or stone lined. I can see how the the clay in that photo made it practical though.

Can someone direct me to a more detailed explanation of the solar water heater using pipes and two windows and the fan powered by solar/battery?
Thanks,
Martha