My Homemade Greenhouse

I just finished building a small greenhouse that I plan to use for plant starting in the spring.  I think I overbuilt it a bit, but I was concerned about the snow buildup this winter.

I started with a frame of pressure treated 4 x 4s and beveled them on the end because I plan to drag the greenhouse to another location next summer when I’m done with it.

Base with corner braces

Base with corner braces

Base with beveled end, the better to drag it

Base with beveled end, the better to drag it

I decided to go with a 12/12 roof pitch to help shed snow and five foot sidewalls to give me just enough headroom in the center.   After cutting thirty-six plywood gussets, along with studs and rafters, I laid each set out on my basement floor and nailed them together.  Okay, you probably see the screw gun sitting there and are thinking I didn’t really nail them.  I screwed the first one, but the rest were nailed.  It was faster.

One of six frames

One of six frames

Some time later, the six frames were built and ready to go.

Yep, count 'em ... six frames

Yep, six frames alright

A few days later I got the frames screwed to the base and braced.

Starting to look like a house

Starting to look like a house

I messed up in calculating the roof rafters and somehow missed the correct length by 7/16 of an inch.  As a result, the sidewall studs are not exactly parallel to each other.  Can you tell which way they are off?  Leaning in at the top or out at the top?

Tilted sidewalls or is it just the camera?

Tilted sidewalls or is it just the camera?

With a little help, I got the 6 mil greenhouse film placed on the frames and fastened it down.  It’s supposed to be good for about four years.  See the channels at the bottom with the wire-spring things inside?  Well, probably you don’t in this picture, but click on the picture for a big version and you will.  I had heard that the wire-spring stuff was called wiggle wire, and when I tried to put it in, I found out why.  You have to wiggle the wire, first up, then down, then up, then down as you work each  bent section into the channel.  It went pretty fast, once I was on to it.  Maybe I would skip it next time though, to save some money.

I like it!

I like it!

The white material on top of the rafters is some kind of packing material that I had lying around.  I thought it might protect the plastic from abrasion against the two by fours, and it was a lot cheaper than the felt tape in the greenhouse supply catalog.  I suspect it is going to mildew eventually.  Sigh, I wish I would have done a less ugly job of cutting and installing it.

In order to hold the plastic around the door frame and the frame against the house, I used two strips of wood, each 3/4″ by 3/4″.  One was nailed to the frame and the second was screwed right next to it with plastic trapped between them and under the second one.  I just pulled the plastic tightly across the first strip and pushed the second strip into place and screwed it.

Here’s a closeup of it.

Over the left strip and under the right one.

Over the left strip and under the right one.

To seal against the house, I cut pieces of foam.  It’s called sill seal and I think I paid five bucks for a roll at Home Depot.

Not pretty, but I think it will work.

Not pretty, but I think it will work.

I covered the shelves with galvanized metal lath that you can buy at any building center.

Inside

Inside

I made the door from 1 x 3 stock, fastening the pieces together with pocket screws.  The top panel has acrylic plastic, but I cheaped out on the bottom with a piece of styrene fluorescent light cover.  Bad idea.  It cracks really easily when holes are drilled in it.  If it fails, I’ll spring for acrylic, which will no doubt happen in the dead of February.

And now it’s done.

Hey, it's a greenhouse!

Finito

It’s a bit on the homely side, but should do the job, I hope.  The materials cost about $280, which seems like a lot, now that I think about it.    Really, though, I suppose it’s pretty cheap for a fifty square foot greenhouse.

I will be putting a bunch of black water-filled plastic five gallon buckets inside to act as a heat absorber and radiator to see how that works, solar energy-wise  Unfortunately, I have only white buckets and black paint probably won’t stick to the polyethylene very well.  Still, I will try.

Update January 9, 2010********************

The greenhouse has been doing well for two years, but I really need more room for plants.  I decided to bump out both sides, leaving the base the same size.  As it turned out, the rock wall on one side kept me from expanding in that direction, so I settled for a one-sided bump out.  I hope the greenhouse doesn’t tip over when I fill up that side with plants.

All I did construction-wise is to extend the rafters with 2 x 4s and run more 2 x 4s under the plant shelf to meet the extended rafters.  I didn’t think to take any pictures of the process, but here are a couple of photos to show how it ended up.  It now looks like a backward 4.

I think the homely factor has been bumped up too.

More room!

I’ve now doubled my space, though I’ll be able to keep only short plants on the far side of the new shelf.

TM

Comments on: "My Homemade Greenhouse" (69)

  1. FlowerLady said:

    I think you did a great job TMan and you will enjoy it I know. Just think how this will speed along your gardens next year.

    FlowerLady

  2. I don’t think it is homely at all! Wonderful structural bones. I like how you can walk out from your basement into it. That is very clever.

    Cameron

  3. Thanks, FlowerLady and Cameron. I’m going to have a good time next spring.

    TM

  4. Thanks for a very informative pictorial. I am wondering how you did the beveled edge on the foundation and how you accomplished the lap joints. I have never done either process.

    What fun you have ahead. I really enjoyed the hoophouse I built until Mother Nature stepped in with a tornado!

  5. Glenda – I accomplished both things with the carpenters’ standby –a circular saw. I set it to 45 degrees and ran it down the 4 x 4 and presto, instant bevel.

    To get the lap joints, I set the saw depth to 1 3/4 ” and made multiple passes across the 4 x 4. Each pass was maybe 1/4 ” from the previous one, and when they were done I had a series of thin pieces still standing. I knocked those out with a hammer and cleaned up the bottom of the notch with a chisel. I’m sure that a picture would be easier to understand than my words, but I didn’t think to take one. Hope this is clear enough.

    Thanks for writing, Glenda

    TM

  6. Nice greenhouse dad!

  7. Sorry, Erin, I’m not quite getting your point.

    TM

  8. Erin, thanks for the pingback. I guess that was your point. 🙂

    TM

  9. Hello there,

    I appreciate very much your suggestions. We are
    going to be opening a small business this spring. It is going to be called; “Earthworks”
    Vineyard/Nursery & Gallery.

    We have been kicking around the idea of building a small green house for propagation needs.

    I think we are going to use your suggestions as a springboard for a larger version (probably 8×12′), corrugated translucent roof panels & 2×4 framing etc.
    You definitely got me thinking.

    If you ever need the services of an illustrator
    you know where to find one.

    Thanks again,
    Dave

  10. Thanks, Dave. I sure hope there is something in the article that you can build from. I would have liked a bigger one myself, but mine had to fit into a pretty tight space if I wanted to have it attached to the house, which I definitely did. I’ll be posting again when I get a few things started in late winter/early spring.

    Good luck with your new business and your greenhouse if you go ahead with that this year.

    ThinMan

  11. gotta garden said:

    Fantastic greenhouse! I would like one, one day, so I’m saving your photos to show to DH, who is very handy. Kits are too expensive. It looks just the right size, big enough, but not too big to waste all the heat escaping. Thanks for posting.

  12. Thanks, gotta garden. You could save a few bucks by using fewer frames and spacing them farther apart. I was being cautious, but after watching how mine has been acting so far this winter, I think 4 feet apart would still be plenty strong.

  13. good work !
    Im going to do the black bucket thing .
    Well I have white buckets too but they are going to have a black plastic bag over each of them and voila, black buckets! well thats the plan.

  14. Nice job, I actually built a very similar greenhouse, and was also thinking about using black 5-gallon buckets of water as a heat reserver… how well did that work for you?

  15. Thanks, Chris and Corey. I’m sure my water buckets did some good as far as keeping things warmer inside at night, but there’s no way to really know how much. I think that it must be better with them than without them, and that’s good enough for me. I know that no plants froze, but some nights I chickened out and moved them all inside.

  16. Its not homely at all! Its spectacular… and I am more encouraged about making one myself, or several. I live in Ks and my husb is deploying (AGAIN!) and I will be doing this alone, he can only do so much before he leaves and we work constantly. the greenhouse is a “have to wait” item and I dont want to wait…

  17. thinmac said:

    Wow! The word spectacular just has never come to mind whenever I look at my greenhouse. 🙂 Thanks, Jo, for making my day, and I’m glad that you were encouraged by seeing it. Good luck with yours, and tell your husband thanks from me for all he’s doing over there.

    TM

  18. Merry Yeoman said:

    This reminds me of the one I am building now! I have 6 frames as well. I am using old windows and some recycled wood but not all so I know what you mean about the price surprising you. I will try to share pics of mine as well but not very comp savvy so we will see. Thanks for being inspiring.

  19. Hey, Merry Yeoman, good luck with yours, and if you get any photos posted anywhere, please let me know. I’d like to see them. I’m glad you got some inspiration. Now comes the perspiration.

    TM

  20. Thank you for posting this. I think my son or father could actually help me implement this plan… sure would make me happy! I’ve been lugging my seedlings in and out of the house in large plastic makeshift “greenhouse” bins.

  21. I sure would like to know how it has held up and what more you’ve learned from your experience.

  22. Hi Cinny. The main thing I have learned from my experience is that the greenhouse is too small. 🙂 I made it to hold twenty flats of plants and I really need it to hold fifty now. Also, I need better ventilation in there for those sunny spring days. Otherwise, it has been doing a good job and holding up very well.

    I’m actually about to add a post here where I show how I bumped out one of the sides to double my room inside. I hope to get it posted today.

    Thanks for your interest, and I hope you get yours going for spring.

  23. It’s good to see you posting again. 🙂 Your greenhouse looks great to me. How do you keep the grandkids from using it as a clubhouse? 🙂 ‘Maybe not as much of a concern in the winter. 🙂

  24. Hi Val, it’s very good to hear from you. I haven’t seen you on the CG forum in a good long while. I actually don’t keep the grandkids from using the greenhouse, especially in the winter. They like to play in there on a cold day when the sun has warmed it up to about 70. Boys, trucks, and dirt, the unholy trinity. 🙂

    TM

  25. Beautiful! I’m looking for an inexpensive way to let my 7-year-old gardener work with his plants year-around. His birthday is coming up in February, and this looks like an excellent option. Do you think you could later add recycled windows to the frame, as you come across them, and eventually convert it into a glass greenhouse? We have a half-dozen windows and it would be great if we could use them for part of it, and plastic for the rest. What do you think?

    Thanks for the great photos & ideas. You’ve got my wheels turning!

  26. Hey, C-cat, as far as the windows go, I’m sure it can be done. A problem with found windows that you probably already know is that they are always all different sizes unless you get really lucky. It complicates the construction, but I’m sure perseverance will win the day – eventually

    I’m glad you got your wheels turning.

  27. I like the bump out… Looks cute!

    I found this today but its pretty big: http://www.buildeazy.com/greenhouse.html I really appreciate that you and others have shared your ideas. Thanks

  28. The Buildeazy looks like a nice greenhouse, Cinny. I wish I could have made mine that wide.

    You’re welcome. Thank YOU!

  29. I am very impressed by this greenhouse. I have been researching diffrent types of diy greenhouses for quite some time now and this is the best! I live in a heavy snow belt in New Hampshire and I was concerned with the possibility of a cave in with most I have seen. I know this would stand up to the toughest of winters and I think it looks the most like a professional, quality built structure. The price is by far lower than even a flimsy pvc hoop house and because your greenhouse is portable it can be dragged to a new area for crop rotation when plants are set directly into the soil as in a hoop house. This is amazing! You really created a perfect greenhouse/high tunnel. (I have seen manufactures charging tens of thousands of dollars for much less quality products)
    I would like to thank you for sharing this with us, the photos are great, the narative is complete and detailed and the structure is wonderful! You have made it very easy to understand!
    Thank You!
    Kim

  30. Thank you, Kim! I am very impressed with your very kind comments. I was doing a lot of smiling as I read it and I think I am going to print the whole thing and post it inside the greenhouse. You’ve made me happy that I took the time to write up the blog.

    Thanks for making my day.

  31. Thank you so much thinmac,
    You are also very kind.
    I think you should patten this greenhouse as it is an incredible one of a kind design.
    This is now my favorite page!
    I love to look at the pictures and daydream about being in one of my own.
    I would like to ask a few questions?
    What has the lowest temp inside and outside been for the greenhouse?
    How many hours of sun does the green house get?
    Is it possible to put a woodchip type compost heat system in it, under the benches?
    I can’t wait until spring to start building one of my own!
    You have also made me smile, with your kind comment and your loveley greenhouse!
    Thank you very much!
    Kim

  32. Kim, the greenhouse doesn’t get used in the winter, so the coldest temp in there is whatever the outdoor temp is. It is on the south side of the house so it gets sunlight all day long. I don’t know much about the compost heat systems, but I would think to you build pretty much anything under there you wanted to.

    Good luck with yours.

  33. I used to be very pleased to find this internet-site.I needed to thanks to your time for this glorious read!! I definitely enjoying each little bit of it and I’ve you bookmarked to take a look at new stuff you blog post.

  34. Thank you, Buford. I’m glad you have enjoyed some of what I put here.

  35. Is there any way to print the homemade greenhouse instructions without having to print all of the comments??? I’d like to save paper and ink. Thanks!

  36. Is there any way to print the instructions for the homemade greenhouse without the comments?? I’d like to save paper and ink. Thank you! :}

  37. Pattie, you could try this:

    1. Open a blank document in your word processing program.
    2. Go back to the blog and highlight the first block of text, not including any picture.
    3. Copy and paste the highlighted text into your word processor.
    4. Repeat steps 2 and 3 until you have all the text in your document.

    It’s a little bit of work, but I think it should do the job.

  38. Hi, any updated pics? did it mold? thanks!

    • Hi, sdeds. There’s nothing really new to report or show with my little greenhouse. It’s still working well and with the bump-out on one side there is more room, though I still had more plants than space this spring. I haven’t seen any signs of mold anywhere. Other than the pressure treated base that sits right on the ground, it stays nice and dry inside. Thanks for taking an interest in my humble project.

  39. Very nice greenhouse thinmac. One of the nicest I’ve seen on the internet. Just a couple of quick questions. Although you do not every really say it, I believe the original size is 5′ x 10′? With your studs and rafters at 24″ spacing? And in the comments you say that the frames could probably be spaced 48″ apart and still be strong enough? Therefore, do you think it could be increased in length to say 12′ with the same six frames- just spaced a little wider? Also, I am assuming that with 5′ sidewalls and a 5 foot width, a 12/12 pitch gives you a 7 1/2′ peak at the ridge? (Math not being my strength). Also, if built as a stand alone structure (not against the house) do you think that a door at each end would help with ventilation? Sorry for all the questions but I am really interested in your project. My wife has been after me for years about a greenhouse and yours seems just right. Thanks in advance.

  40. thinmac said:

    Hey Eric, I’m glad you wrote. I like to answer questions, especially good ones like yours. Yes, the original size is 5′ x 10′ with the stud/rafter frames at 24″ spacing. I’m sure you could stretch that out to 12′ with six frames and have no problem at all. In fact, I would encourage you to also bump it out to a 6′ width, keeping the 12/12 roof pitch, or maybe going to 10/12. Here’s why.

    1) It will let you put a bigger door in the end(s). Mine is really narrow (21″) though I made it as wide as I could and still get enough height for me.
    2) It’s pretty tight inside when you get a row of 20″ plant trays on each side. An extra foot would be mighty nice. I just didn’t have the room to do it.
    3) Extra height would really come in handy for hanging plants.

    You are right about the 7 1/2 ‘ peak in the size I built.

    I’m sure that having a door at each end would help a lot with ventilation, and it definitely needs ventilation on a warm sunny day.

    If you come up with other questions, just shoot them this way, and I’ll do my best with them.

    TM

  41. Thinmac,

    Thank you very much for your reply. I am already planning on expanding mine to 6′ x 12′. (My wife says “No Eric, make it 8′ x 16′ NOW and we wont have to expand it later.” She is probably right, but since I am the builder and she is my ‘adviser’ I am sticking with 6′ x 12′ with an 8′ peak. That still gives me a 12/12 roof pitch and the angles at the sidewall gussets are a friendly 45 degrees. At least I am sticking to that for now.)

    A couple more questions that I can think of are:

    1.) What size plywood did you use for the gussets? It is a little hard to tell from the photos, but it looks like 3/4″. It may be 1/2″ though.

    2). What height are your plant shelves at? I would guess by looking that they are at about 30″?

    3.) I notice from a couple of the photos that you seem to get some pretty harsh winters with lots of snow. We get the same type of winters here. How is the 6 mil clear plastic holding up after a few seasons? Would you still recommend 6 mil or would something heavier be even better?

    Thank you again for all of your help.

  42. thinmac said:

    Ah, defying your wife. You are a brave man and an inspiration to us all.

    I used 5/8″ plywood for the gussets, only because I had some pieces sitting around. I would guess that even 3/8″ would be plenty strong enough.

    The tops of the shelves are 36″ high.

    The 6 mil plastic is regular greenhouse film that is rated for four years of use. I’m in the fourth year now, and, aside from a couple of holes that I have managed to put in it, it is holding up very well. I have the same stuff on a hoop house that I built and it’s doing well there too. The snow hasn’t been the problem that I thought it might be. It’s easy to step into the greenhouse and knock off the snow by smacking the plastic with my hand – it slides right off, sometimes all by itself.

    I looked at other alternatives to the plastic film, but they were all more expensive.

    It sounds like you’re really getting into it. Go Eric!

  43. Hello Mr. TMam
    My dad and I are thinking about building a greenhouse similar to yours an I was wondering if you could tell me how you made sure it didn’t over heat or freeze? Our summers are quite hot and humid ( 106 was the highest day) and our winters can get to 32 degrees give or take.. I’ve gotten books but some of their ventilation ideas are a but complicated.. Thank you.

  44. Good question, Mani. The heat is definitely a problem, even here in northern Michigan. I built a vent on top, which you can see here: http://thinmac.wordpress.com/category/greenhouse/page/2/

    Opening the vent and the greenhouse door helps keep it cooler inside, but it still gets too hot on a sunny warm day. A fan in the doorway helps too, but I still can’t keep it as cool as I want.

    As for freezing during the winter, I just let it freeze because I don’t try to use it then. In early spring, when I am using it and we are still getting down into the twenties at night, I will move the trays of plants back in the basement for the night.

  45. What an inspiration…..will be doing this one!

  46. Thanks a lot, Norma. I’m glad I could inspire you.

  47. Fabulous! This is one of my favourite home made greenhouses. I’ve just shared the link on my latest blog post and hope you didn’t mind me using the picture, it’s so impressive! 🙂

  48. Hi Dee, I don’t mind at all. Thanks for the link. I checked out your blog and wow, that post is pretty comprehensive. I’ll be going back to read more.

  49. So happy to have found your blog. I think this is a project for the upcoming season. Thanks so much for posting such comprehensive instructions!

  50. Glad you liked it, and thanks 🙂

  51. I wish I could build one. I looked at some cheapely made ones today and they were over $500.00 I kid you not. There garbage. This is A nice One. Good Job. You should be proud of your self. And I saw nothing HOMELY about it what so ever! I would give you an A +

  52. thinmac said:

    Thanks a lot, Melody, for the A+. I don’t think I ever got one of those before. Hope you can get a greenhouse for yourself some time soon.

  53. I think it looks great! My wife has been hounding me to build her a green house, but I thought all the plans and materials were way too complicated for our purpose. This I like a lot!!!!!!

  54. thinmac said:

    Glad you like it, Mitch. If you can make it even a foot wider, it will be worth it. Mine is just a little too narrow for comfort.

  55. Katy from Tooele said:

    My husband directed me to your blog. I’m so glad he did! He’s a non-traditional architect student (aka old!) and spent years as a construction superintendent. He is always on the lookout for cost-effective, green construction. I love love love your beveled edges for a portable structure. I think the arches to accommodate height are beautiful in its simplicity and great for function. We are designing a hen house right now to increase our compost production. I’m sure we may snag a few of your ideas. Thank you!

    • thinmac said:

      You’re very welcome, Katy. Please feel free to snag anything at all. I love it when someone writes to say they can use something that I posted.

  56. awesome!

  57. You could put the white buckets in black garbage bags instead of painting them black. Nice project.

    • Good idea, David. In fact, that is exactly what I did. Thanks for your contribution.

  58. T.Heiss said:

    SWEET ,iLL BUILD MINE FROM RECLAIMED LUMBER

  59. Hello “Thinmac”!
    Any Suggestions on reversing your GreenHouse plans to a “Cool Greenhouse”? Temperatures here 75*-95* year round. Problem is the plants need sun!

    • Hmmmmm. I don’t know much about that kind of problem, but I probably wouldn’t have a greenhouse at all if I lived there.

  60. Brent Eamer said:

    Growing your own food is never homely. Good work man! Damm cozy, right good for a shot of Scotch in the dead of winter I’d say

    From Prince Edward Island, Canada (home of the never ending spring)

    • thinmac said:

      Thanks, Brent. That sounds like a good thing to do on a nice sunny winter day.

      TM

  61. Great job TM. I have always wanted a greenhouse but never thought it would work in my back yard which has high shade. Come to think about it, the leaves are gone in the winter.

    Have you thought of using tie downs on the side without the bump out? People who live in mobile homes have to use them in case of storms so why not on your project?

    I wish you many years of joy using your greenhouse. If you ever get to Alabama, I would be delighted to allow you to build one for me, ha ha

    • Thank you, SSBren. I imagine that with your mild winters in Alabama you could probably use a greenhouse through the winter, so maybe you should give it a shot. The tie downs are a good idea, though luckily, it turns out that the bump out doesn’t make the greenhouse tip over, at least not yet. I’ll keep you in mind if I ever feel like building a greenhouse in Alabama. 🙂

      • As Bob Barker used to say on his game show, Come on down. I think my days of gardening are over and it breaks my heart, No one can do it like I can. When I see the grass cut and edged but nothing done to the flower beds, I feel like crying.

        I am thankful for all of the wonderful years that God gave me to grow beautiful plants on his green earth. This summer has been so wet, it is sort of like last year…..a lot of things aren’t doing well in gardens but my flowers have shown out. Especially, the hostas and ferns.

  62. I like this. I’m thinking about putting chipboard on side and making shed. I like!

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