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greenhouse Greenhouse Ideas

W

wordwiz

One way or the other, I will have a greenhouse up by this fall. Been visiting a lot of different forums, reading articles, even have a book that covers a ton of stuff. But where it has led me is to the "educated idiot" status. There is still so much to consider and I'm sure there is stuff I don't know that I don't know or even need to think about.

The basic design I'm sure about - a lean to type. The back (north) and west wall will be wood - the amount of light I will lose is minimal. My office window faces the same way but does not have a clear roof or walls, yet tomatoes, lettuce, beans and peas are doing quite well in it. It will be 12 feet wide by about 16 feet long. That will allow for two 4' benches which can hold a total of 70 seed trays with a 4' space between to work in, or 60 hydro buckets with 1.5' on one side of each row and 3' in the middle.

The wide walls will be detachable so once the weather gets warm enough I can remove them. The back wall I'm hoping I can get away with only being 8' tall with the fron one 6'. I don't know if that is enough slope over 12 feet or not. If I have to, I can go with a 10' back wall.

The covering for the roof, front and east side wall will be plastic, but what type I don't know. Clear vs. translucent? Special GH film or 6-mil plastic? The type that is UV resistant and refracts heat back inside or not?

Probably will not have any special lighting - maybe a couple of shop lights or CFL bulbs so I can see after dark but no grow lights. Going back to the plants in the office - even without near as much light, they are doing great.

Heating will be via two electric heaters that should be enough to keep 200 sq. ft. above 50 degrees except in sub-zero nights. For those 6-8 nights per year, I'll have a kerosene heater that will provide 20,000 BTU. I would also like to install a very basic passive solar heating system. Typically, in OH winters, the most frigid nights have bright, sunny days. This might have to wait a year, though.

So what haven't I thought of and what is your recommendation for covering? Plexiglass and other high priced options are not options this year!

Mike
 
I know how it is to dream of what you want and how to make it, especially something so important and costly. I have no suggestions but cant wait to see pics of what you create.
 
Mike...I saw this when you posted it and just now have time to respond...

if you design it right, you will only need the wall facing the sun transparent...I have posted this before and don't know if you have looked at it or not..it is a link to "solar greenhouse design"...bottom line, you want the transparent wall 90 degrees to the sun in dead of winter...you can find the angle of the sun above the horizon for your neck of the woods online...

http://survivalplus.com/foods/page0009.htm
 
AJ,

I had read that and am trying to incorporate most of this ideas into my design. Probably won't go with the back walls being lined with water containers, but am looking at lining the wall with a cheapo garden hose that runs back and forth (as close as possible between rows) that is covered with a blue plastic. The blue is so that that spectrum will be reflected back on the plants, but it still absorbs almost as much heat as does black plastic.

I pretty much know the angle of the roof should be greater, but since I am building this in my backyard and don't want to have to deal with the zoning cops, as long as I keep it under eight feet I don't have to worry. I might even be able to get away with 10' but I prefer not to chance it. But the south wall faces almost perfectly to collect sunlight, at least at this time of the year.

One thing that was suggested in the Garden Forum was to not worry about making the side walls detachable, but instead use a fan to exhaust the heat. I love this idea!

I'm sure my initial set-up will be ghetto but then again I don't care!

Mike
 
I posted a similar message in another forum and one response for the outer covering was this one. The price is fantastic and the guy who recommended it said it lets in enough light to kill an orchid and that is using just a single layer.

If you try to get an idea of the total costs, including shipping, ignore the calculator for widths over 9'. They run about $10-11, not $102.

I still need to raise about $700 from plant sales and web site design to build mine but I am getting closer.

Mike
 
Mike...that looks like the same stuff I have on my greenhouse...can't really tell from the pic but from the description, it sounds like it...

the finished product that has grommets every 2 feet and is hemmed for the roof of the greenhouse is about 100 bucks...it is very durable and has withstood up to 70mph winds since I put it up...we had 60mph winds Thursday...it has been a very windy March so far....it is very still right now...

being able to buy replacement roofs, sides and ends is one reason I went with what I bought...
 
I'd go with detachable walls, roof vents, and/or make several large vents at floor level to make cooling easier. I personally use commercial intake fans, exhaust blowers and shade-cloth, and still have problems keeping the temps down when its sunny. My next greenhouse will have sides that roll up a bit leaving a couple feet around screened-in, as well as some roof vents
 
I've been reading a bunch about GHs and am amazed at how involved they can get. The "Big Boys" use an air exchange unit that mixes CO2 with the air and then blows it in from under the plants.

Do a Google search for Eurofresh in Snowflake, AZ. 318 acres of GHs. They are producing over 200 million pounds of toms a year.

I'll probably use 4' sections on the side walls to make it easier to attach or remove them. It's weather such as we are having now that will be a challenge. Yesterday, it was 73 and very sunny, Sunday it is suppose to get down to 28. The only way I can think of dealing with this would be to also have two large doors (one on each end) I can open and close.

Mike
 
The greenhouses I've worked at use propane burners to produce C02, and these burners are hooked up to perforated inflatable plastic tubing which stretches the length of the greenhouses. We used compressed C02 tanks in the past, but thats gotten to be far too expensive.
I've always liked the idea of removable, or roll-up sides and one day I hope to have a simple greenhouse and loads of chili plants like "Chilifarmer" in Texas
Check out his recent chili pic
http://chilefarmer.blogspot.com/2009/04/chile-plants.html
 
Potawie,

That is one huge bunch of peppers! Does he also raise onions?

How important is a CO2 generator, especially in winter? Can I go with just a CO2 tank and distribution system (if it really helps)? The Burners seem rather expensive (~$1000 for the burner and controller) while the simple Injection system if about $150.

Mike
 
Potawie,

Wow - they plant all those onions by hand? I would have thought they used some mechanical method. We used a tobacco setter to plant toms and potatoes also. It really cut down the time, especially for the potatoes.

I'm planning on growing mostly tomatoes in the GH, though I will have a couple of trays of lettuce, broccoli and peppers. May even try a couple of pole beans. My buckets are 3.5 gallon kitty litter ones that are about 12" wide x 14" long. A lot will depend on how well my Siletz tom does at the office. If it can produce four pounds of toms in a week (that would be less than 8 toms) and I can find a market at $1 per pound, I would probably have about 50 of those plants growing at a time.

It's been about 50 days since I first put it in water and I have about a half-dozen blooms and another couple dozen buds. Haven't tried artificial pollination yet, they are suppose to self-pollinate. One other plus for this variety is that it is suppose to set fruit in 55 degree weather, which would really help the heating bill in winter.

Mike
 
I keep forgetting where you are from Wordwiz, but when they say 50 days I think that would be in ideal conditions and IMO it would be difficult to have ideal conditions in the winter without adding supplemental lighting, heating and C02. They've recently developed several varieties of "cold house" tomatoes which are supposed to do much better in colder environments, but I haven't tried any yet.
 
Potawie,

Cincinnati. The Siletz is supposedly a 55 day (ideal) to 75 day (almost worst case) tom. It was bred to grow well in the Pacific Northwest where the high temps are in the upper 60s.

My goal is to have a ripe tom by Derby (Kentucky) Day - May 2.

Mike
 
Just an update on my "I have a dream" idea! The tomato plant is producing several fruits without a lot of intervention which is the fuel for this fire.

Probably putting the horse before the cart, but IF (notice it's a big if!) it produces 36 pounds or so of tomatoes and it stays about the same size and the toms taste good, I may have to revise my GH height to eight feet. That would allow me to have two tiers of plants or 128 plants total. In theory, I would be able to harvest as many as 600 - 750 pounds of tomatoes per week. That would become a serious adventure.

Not that I would start with that many, but if I build it only six feet tall, and it works, then it would be far more difficult to change.

The longer-term goal is to show that it's possible to make money growing GH produce in Cincinnati. If I can show a decent income from a 200 sf GH, then maybe investors will look at a 10,000 sf one.

Mike
 
I'd go as tall as possible if you want to grow tomatoes in the greenhouse. Some of mine easly outgrew the 10" greenhouse last year.
Try to take a tour of a tomato greenhouse sometime, its interesting how the pros do it
 
Potawie,

The toms I am growing (if they taste good - I should know in a couple of weeks) are determinate and don't get much over 3' tall.

The dilemma is to make it as tall as needed but not any taller, especially since I want to grow year round. Higher ceilings mean larger heating bills.

There's a commercial GH up the road about 75 miles that I may try to get to this summer. They are not open in winter, unfortunately. But I've seen pictures and read quite a bit about Eurofresh's site in Snowflake.

Mike
 
Another idea - will this work?

If (the biggest two-letter word in our language!) I can make a decent amount of money selling produce this fall and winter, with decent being $150 per week net, setting aside a portion of that to buy replacement windows. The south wall would be be lined with them with only enough space in between to support the framing. The west wall would have two large ones, the other walls none, though the east wall will have a door. I would also probably find a couple to stick in the ceiling. In spring, I can open however many windows I need to keep the temps in check, in summer it would be almost like a screened-in porch without a roof, and in winter, the glass would be an excellent barrier. I can also use 4 mil plastic in the very coldest weather as another way to keep the cold out and the heat in.

Keep in mind, one of my goals (besides production) is also sustainability in a hugely variable climate. Our lows range, on average as chilly as -5F, with record lows 20 degrees colder. Our highs average in the mid-90s, with a couple of upper 90, low three digit days not unusual. It probably isn't fair to compare the cost per sq./ft. if I buy stuff off Craig's list but then again, if I was to build a 100,000 sq./ft. GH (or make the proposal to investors to do so), I suspect a window company would really cut their rates a bunch!

Mike
 
WW-
Your biggest design concern will be temperature variation. Even up here, I've had 100°+ temperatures when ambient was ~30°. Me personally if I was you I would not build for having removable walls if you are wanting to extend your growing season into the winter- the benefit you would get from open walls in the summer (not having to have cooling fans) would be GREATLY offset by the drafts you will inevitably incur in the wintertime unless you are willing to spend a lot of time and/or money to design and fabricate a system that you can seal off well. An open door and an exhaust fan will do just the same as removable walls and will serve you much better. I don't have any decent pics of my work in progress (barely had enough time to move in to the new house and get the greenhouse set up and running evenly enough to leave this year's starts out there!) so I'll try to explain myself with the pics I do have.
The first pic is taken looking directly West before I started work. The old greenhouse is 10x12, running lengthwise East/West. I replaced the opaque fiberglass on the Southern wall/roof with new clear polycarbonate siding. I found a MAJOR score in the storage shed on the new property- two HUGE thermopane windows, which I placed on the West facing wall. I ripped all of the old opaque fiberglass off of the Northern side and replaced it all with 3/4" plywood. I put scrap insulation on the inside of the 3/4" plywood (still itching from that). Putting up the plywood and insulation made a huge improvement in being able to hold the heat at night and I think it actually may have served to even out the daytime temp as well, though I don't have any evidence to back that up other than my own perception.

yard1.jpg


This is a pic on the inside, again looking directly West. You can see the insulation on the inside of the North wall as well as where I put plywood on the Northwest of the roof which I will be insulating as well.

lettuce7.jpg


Another thing- do not discount the importance of thermal mass. I put 4 black poly 55 gallon drums and a mess of black storage totes in with a total of ~375 gallons of water in black plastic. I put the totes on the North bench (some of them are pulling double duty as lettuce rafts) and I put the barrels in an East-West line in the middle, creating another benchtop. I filled all of 'em straight from the well which was maybe 48°. Greenhouse temp was 88° when I started filling, and by the time I was done the air temp was down to 70°. It was pretty interesting watching the temperatures over the next few days as the water warmed up- and once it reached a stable temperature it was really interesting seeing the spikes cease. I highly recommend that you explore this- the thermal mass not only keeps the temp from swinging too low at night, it also keeps the temp from swinging too high in the daytime which is just as important.
Also, air movement is incredibly important. I put in an industrial exhaust fan that is controlled by a thermostat- altogether it was really cheap, and it cools that shack down in a hot hurry, pardon the pun. It's really easy to put something like this in, and you can power it with an extension cord from your house. If you don't think you can tackle something like that (trust me, you can!) then you could buy a thermostatically controlled box fan from the Home Despot. I have not tried one with the thermostat on it but I do have a couple Lasko box fans hooked in to my daytime timer, one in the eaves blowing hot air down and another on the ground, circulating air. This is very beneficial, as it strengthens plants, aids in pollination, and it eliminates hot and cool spots.

Prior to all this work the lows at night would get down damn near to ambient which was about 29° even with a natural gas heater running WFO. After all this work and with the natural gas heater set at low my low temps were a steady 55° when the ambient low was 29°. I currently have the exhaust fan thermostat set to kick on at ~80°. I will up this as the nightime lows increase, trying to keep day/night variation at a variation of about 15-20°.
 
Hinky,

Thanks for the ideas (though they would have been easier to read had the image been about 800 pix wide!).

What I'm leaning toward for next spring/late winter is to have made enough money selling toms during the winter to afford two large replacement windows (preferably four!) that I will put on the east and west walls. Like you, my north wall will be wood and heavily insulated but I also intend to do the west wall the same but hopefully adding the windows. I will also have a place for a box fan on the west side and a door on the east.

As time goes on, I'll try to replace the plastic on the south wall with windows. The idea would be that in a year or two, I'll have windows that allow a lot of light through but also are energy efficient in winter time, even if it means adding a layer of clear 4-mil plastic in the dead of winter.

I do want to take advantage of solar heating as much as possible, even though it is not real reliable in January and February. Several years ago, my former neighbor, a rocket scientist, and I worked out a plan whereby I could run thin walled garden hose back and forth across a roof and pump water from the pool through the hose and back into the pool. He calculated that if I moved a gallon per minute, I could raise the temps of 22,000 gallons of water by 1-2 degrees per day, based on different factors. My plan is to have the pump hooked up to a thermostat and use a water heater to store the water. If needed, I can use two or three heaters and run the hose along the ceiling also. Once the water inside the hose warms above a certain point, the pump kicks on and will constantly pump water, until it cools down. Another pump will be set to kick on when the temps drop below a set standard but will pump the water from the water heater to small radiators, more than likely located under the plants growing in hydro chambers. This would allow warmer air to rise around the plants plus provide a bit of heat to the water.

I already have a 12/2 with ground cable running to the site and though it is on a 20 amp breaker, I can switch that to a 30 amp. I don't intend on running grow lights at all, but I will use a few CFL bulbs to light it, be running at least 800 watts in electric heaters, have enough air pumps to power 64 stations and have a couple of fans. All in all, less than 1500 watts.

Hopefully, I'm prepared for this. I've rehabbed four homes, installing insulation, hanging drywall, running electricity and plumbing, putting in windows, replacing water heaters, etc. The only thing I know is I don't know enough - one corporate trainers described it as not knowing what you don't know. In other words - things one doesn't even consider, such as having a way to drain the reservoirs when the water gets funky. I know about that now but never thought about adding drain plugs and a drainage system until I had to replace some water today. I managed to do it, but it's not easy with a huge tomato plant growing and it has long roots!

Mike
 
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