Thinking About Building My Own Greenhouse - Any Tips or Suggestions?

[TheSeedObsesser]

I'm thinking about building my own greenhouse. I want to start it out unheated and maybe make it heated later on. What are the best materials to make it out of? Are there any ways to heat the greenhouse without a propane or gas heater? Any tips or suggestions for this newbie?

 

[Smart Red]

One important tip.

Carefully consider how large a green house you will need and can afford. Then double it's size! I haven't met anyone yet who couldn't fill their new greenhouse overnight and need more space. I suspect part of the problem is wanting to see if you will like and use a greenhouse enough to warrant its cost so you select a small design. Immediately you fall in love with greenhouse gardening and dream of the next one you will build -- bigger and better - while you're stuck in the mini one you have.

My 6X8 greenhouse was instantly too small. My 8X12 sun room/heated green house is too small to move around in come winter. I am still contemplating the useful size of my 24X18 garden shed with its 16 feet of floor to ceiling glass facing due south. If I didn't have to store all the garden equipment . . . . and had heat. . . . it would probably be big enough for a few years at least.

We used damaged patio doors as windows for our garden shed. Purchased for $5 to $15 each, we put them along the south wall. Depending where you live, you wouldn't need glass on the north side of the greenhouse. Add insulation and reflective wall material instead.

You can heat with wood (I hope to heat my garden shed with a small wood burner) either inside the room or outside pipped in. If it is close enough to the house, you could even bury a heat duct so that with a fan you could pull heat from your furnace to heat the greenhouse as well.

The best materials, IMHO, are the cheapest ones. You'll get lots of ideas from the redneck greenhouse builders here at TEG, but using your house as the north side wall is a good start.

 

[catjac1975]

Take a look at this post.
http://www.theeasygarden.com/forum/viewtopic.php?id=32911

 

[NwMtGardener]

Huh. Smart Red, you are REALLY SMART. I have no idea, i mean NO IDEA, why this has never occurred to me until now. When you said "wood heat" i realized: My greenhouse (well, it is when its got plastic over it, not right this second) is only a FEW SHORT FEET from our garage. Which has a wood stove. To top it off, the garage has a window hole that only has plastic, no glass. Fer real, it would be the most simple thing to run a flexible ducting out that back window of the garage and over like 4 feet to the greenhouse. Genius!! Man, i can tell already my husband is going to hate this idea!! Haha.

Hi seedobsesser, welcome to TEG! I actually started coming here a few years back because i built a redneck greenhouse, then realized needed a lot more knowledge about how to use it effectively. There are a few good threads on greenhouse construction and hints and tips here at TEG, use the search tab above.

I just use construction grade plastic sheeting, comes in huge rolls in different thicknesses, and is pretty cheap. Mostly its good for one year of use, although this year i was able to recycle most of last years pieces. I put it over a completely recycled framework that is constructed over my raised bed garden, i think the total dimensions are 12' x 24'. We do this in march, usually. Then by june or so i'm starting to have ventilation problems, getting too hot inside as the temps warm up outside, and the sides and ends are rolled up and held up with bungee cords to get more air through. Usually by july it all comes off. So, basically, i use the greenhouse to get my garden started much earlier than would otherwise be possible here in northwest montana.

I use a drip irrigation system inside that helps save me time from watering every day. But it would be nice to have an automatic vent opener that some TEG members have - when it reaches a certain temperature inside, it willcrank open the vents automatically to let in more fresh air and cool it down. With my setup, i have to check what the weather is supposed to be, and try and decide before i leave for work how much ventilation does the greenhouse need? Should i just open the door, or do i need to roll up an end, or all of the sides? So that requires a time commitment from me every morning and night, and a lot of paying attention to the weather, but its worth it.

 

[digitS']

Welcome to TEG, SeedObsesser .

Here is my 9' by 20' greenhouse (sunshed):

There is a natural gas garage heater behind that closed vent above the door. I can use the fan on the heater to help cool the greenhouse on sunny days. There is an exhaust fan at the other end of the structure. The plastic film on the south side is UV-resistant plastic and lasts 4 or 5 years.

Someone said that it looks like a "half a house" and that is about right. You can build the north side completely insulated to help with heating costs. Still, a lot of heat will escape out the south side during the hours of darkness. I only run the furnace thru March and April with maybe a week or so in May, about 7 or 8 weeks.

Steve

 

[journey11]

I have been collecting sliding glass doors and windows. They are fairy easy to come by, especially if you know someone remodeling. Eventually we'll be replacing the windows and doors on my house, so I will definitely have enough then. Glass is so much better than plastic. Holds heat better and is sturdier. Plastic has to be replaced before long. With glass you will get a lot of solar gain as well. For passive heating, one method I have tried with a cold frame/hot bed was to dig an 18" pit and fill the bottom of it with raw manure and then layer on fall leaves and wet it a bit. Then you put your soil on top of that. The decomp will produce heat of its own for about 3 months and combined with the solar energy from a southern exposure, it is enough to grow greens and such or to put transplants in it early.

 

[TheSeedObsesser]

Wow, looks like I have a lot of work and planning ahead! We have a lot of old wood, somebody wanted their deck gone so we took it down and got to keep the wood. The most important thing that I should have while doing this is probably my grandpa, I stink at carpentry. I have never thought about using wood heat before. We have a lot of willow and maple that the county came and cut down that we could use. Considering the size of the greenhouse, I'm thinking something like XXL. I have every window in the house filled with plants in the winter and would like a place to grow tomatoes, peppers, runner beans, etc. year round. So I'm probably going to want to make it heated as soon as possible. I have been looking for window screens for pepper cages to keep the bees out, so It would be a good idea looking for old windows while I'm at it. Thanks for all of the helpful information! This will give me something to do over the winter.

 

[digitS']

Huh. Smart Red, you are REALLY SMART. I have no idea, i mean NO IDEA, why this has never occurred to me until now. When you said "wood heat" i realized: My greenhouse (well, it is when its got plastic over it, not right this second) is only a FEW SHORT FEET from our garage. Which has a wood stove. To top it off, the garage has a window hole that only has plastic, no glass. Fer real, it would be the most simple thing to run a flexible ducting out that back window of the garage and over like 4 feet to the greenhouse. Genius!! Man, i can tell already my husband is going to hate this idea!! Haha. . .

Okay, this is an idea that might pique his interest (or not). It took me awhile to find this: Heating & Cooling Programmable Outlet Thermostat.

A fan could be installed in the duct or, just sit in the greenhouse very near the duct. An outlet near the center of the greenhouse could be the location of the thermostat and control the fan. If it is too warm, the heat can stay in the garage. Too cool, the fan can pull it into the greenhouse .

Steve

 

[TheSeedObsesser]

I looked at your link, digitS. It's very interesting how you can program it to cool/heat the greenhouse when it gos beyond a particular temperature. Good deal for $40 too, I think this can go under my favorites. Sorry that I couldn't look at it for a while. I've been juggling schoolwork and helping a local farmer bail straw for the past four days or so.