Yesterday after school, Monkey Boy helped me put together a small polytunnel {or mini greenhouse} to cover one of our raised garden beds. According to the Farmer’s Almanac, it’s going to be a cold winter up here in the Pacific Northwest and since I’m attempting to grow a winter garden this year, I figured I needed one.
Well, actually, the plan is to build 4 small poly tunnels this winter. 😉
Anywho, turning a raised garden bed into a mini greenhouse is rather simple. Our garden beds are 4 feet wide by 8 feet long with the newer garden beds being 12 inches tall.
We simply screwed in 16 C shaped brackets around the sides of the garden box.
Then slide 7/8″ pvc pipe that was 12 feet long through the brackets.
You could do this on inside of your garden box if you wanted to but I think it’s easier to work with the pipe on the outside of the garden box.
Then, drape a sheet of heavy duty polytunnel plastic and staple it to the bottom of your garden box. Be sure and leave at least one end of the poly tunnel open so you can reach in with a watering can and give the plants a drink as needed. You will get some condensation, but you will need to water your plants as well.
I found my plastic sheeting in the paint section at The Home Depot. Is it air tight? No, and that’s a good thing in my opinion. Why? Because plants need air to breath, and if every nook and cranny is sealed off, tiny bits of fresh air cannot get in.
Here’s what it looks like inside the poly tunnel. Once the weather gets super cold, I’ll close up the other end at night to protect the seedlings from frost, then re-open once end of the tunnel one the weather has warmed up.
Now the only thing left to do is let Mother Nature work her magic. 🙂
How about YOU? Are you trying to grow anything outdoors this winter?
Mavis wants to know.
Judy says
Mavis looks great! And I have thought about doing this myself…
just wanted to know how long was the pvc piping you used?
Sue says
I love this !! Just what I was looking for. I’m also wondering how long the PVC pipe is?
Mavis Butterfield says
12 feet long. 🙂
Laura says
Its listed, 12′
Mavis Butterfield says
12 feet. I’ll go back and add that in.
Judy says
thanks Mavis! 🙂
Kathy says
I don’t know if that would work with our snowy Ohio winters although family in northern Colorado have in years past. My sister’s other half just built her a cold frame out of scrap wood and old windows. Have greens growing already in it for fresh at Thanksgiving!
Em says
Cool, thanks! Could you please let us know what size your sheet of plastic was? I need to build a few of these I think. My beds are also 4×8.
Mavis Butterfield says
According to the package, the plastic is 9×12 feet. I used 2 sheets. 🙂
Lea says
Where did you get the polytunnel fabric?
Kristina says
Mavis, Thank you so much!!! I have been wondering and researching how to make one of these forever now and I look on your site and see this!! I am so happy!! I”m gong to the Home Depot today!! Can I grow lettuce in there all winter now??? Thank you so much for showing me how to do this again!! I am going to make one too.
Mavis Butterfield says
Yes, I think you can, I am going to try growing lettuce as well. 🙂
Jenny says
Looks great, but leaves me wondering how the plants receive water?
Chelsie says
I was wondering the same thing?
Mavis Butterfield says
I leave at least one end of the poly tunnel open so I can reach in with a watering can and give the plants a drink as needed. You will get some condensation, but you will need to water your plants as well. 🙂
Gwen in L.A. says
If it is stapled, how will you reach in to weed? Pop a staple? Then restaple? Hopefully weeds won’t be a problem 🙂
I’m hoping to do something similar, using drip irrigation on my plants in Square Foot raised beds.
Mavis Butterfield says
Just one end is stapled. I pulled the weeds that were in there before I added the tunnel as well.
Kath says
Stick on Velcro may work, then you can open and shut it just separating the velcro strips
Shannon says
We made a tunnel this summer. We didn’t staple the ends, but left them long enough to roll around a scrap 1″ x 1″ on each side. This way, we could just plop one end over to the other side when we wanted to get to the plants. Also, instead of using the C-brackets, we hammered in short scraps of rebar on either side of a box across from each other and slid the end of the tubing over the “stump” sticking up.
sclindah says
You can also just pound some 2 foot rebar into the ground and then place your pvc poles over them. This works great too and easy.
Johanne says
Another person wondering about how you water?????
Mavis Butterfield says
I leave at least one end of the poly tunnel open so I can reach in with a watering can and give the plants a drink as needed. You will get some condensation, but you will need to water your plants as well. 🙂
AshleyO says
Looks great. I get so many good ideas from you. Thank you for sharing with all of us!!!
Steve says
According to the Winter Harvest book, plants need 10 or more hours of sunlight to really grow. As of today (Nov. 1 st) Gig Harbor will get 9 hours and 59 minutes. You next 10 hour day will be February 9th, at 10 hours and 1 minute. I have lettuce and arugula growing on my enclosed front porch in Seattle. Also, lettuce under glass in the garden. The real problem in our area is lack of sunlight. Overcast cloudy days, rain, and fog cut the available sunlight even more.
Cindi says
In cold areas your not actually “growing” during those short winter days. Your are “harvesting” crops that are already mostly grown. That means cloudy rainy days won’t hurt. I did a cold frame with polycarb lights over a 4×6 raised bed. Mesclan, arugula, and some lettuces were good for the early winter. The Mache –Valerianella locusta (lamb’s lettuce), Minutina –Plantago coronopus (buck-horn’s plaintain), Claytonia –Claytonia perfoliata(miner’s lettuce) and swish chard lived all winter. It was awesome to have fresh salad in Jan and Feb.!
Steve says
If you want to know the hours of sunlight for your area. Go the website at http://aa.usno.navy.mil/data/docs/Dur_OneYear.php.
Margaret Thele says
Nice project, Mavis, but I’m wondering how will you reach into the middle to harvest. Will you just stoop or crawl and cut or water? Another way to attach the plastic is to use an 8′ long PVC pipe on each side and attach the plastic to that with tape and roll it. Then you can just roll up the sides…
Lisa Pedersen says
I live in a VERY cold area of Canada and can’t see myself growing much outdoors in the winter (less than 0 degrees F).
That being said, I want to start a cold frame to grow things in April/May and in October/November. At least I can extend my growing season a bit…but I don’t want to shovel snow to get at my food…
Erin M says
Hey Mavis. So we did this. We bought 3/4″ PVC so we thought we had the sme as you. When we tried to arc it, it was too thick to bend and broke the connected. I just came in and red you article again. Yours looks thinner than ours. Our PVC said 3/4″ on the tubing. The measurements are taken on the inside of the tube, so we are wondering if yours might actually be 1/2″ PVC which is about 3/4″ across the outside. The only other thing could be that we bought a thicker walled PVC? We’ll figure out out, but we are just a bit puzzled.
Erin M says
Just to update Mavis. We figured it out. We were using the rigid PVC 3/4″ for plumbing. We should have used the flexible stuff. Duh. My gardening truly is a work in progress. Just when you think you’ve got it……BAM, nope.
Mavis Butterfield says
Ha! Tell me about it, gardening is a total work in progress. I don’t think we’ll ever be done learning.
Wes B says
What is the “flexible” PVC used for normally, and is it available at Lowe’s or Home Depot? Just need to know what to ask for. I think I was looking at the more rigid kind.
Mavis Butterfield says
Plumbing. 🙂
Erin M says
Sorry about all the weird autocorrect weird spellings.
sme=same
connected=connector
red=read
Melissa says
That looks great. Was thinking about doing the same thing. Do you know what mil plastic you got? Just hoping to save time/money by not getting something too thin.
michele says
Easy away to roll up sides, staple plastic to a 1 x 1, will help you hold plastic in place. Plus when you need to open to weed or water and harvest just roll plastic up to the middle and bunge them in place. Also makes it easy to put away for summer instead of trying to fold..
Bryan says
I called Home Depot and was told that PVC pipe cannot bend that much. I will but other pieces and if it bends, it bends and I will take the other stuff back.
Cindi says
I have used pvc for the last 4 yrs. it is still doing just fine. Bending a 10 foot length over 4×4 beds.
LoM says
Just ask for half inch PVC pipe. I got mine (10′ length) from ACE hardware and have it bent over 4′ square beds, it bends extremely easily. I found there was no need to attach it on the outside of the bed, I just push my ends down into the dirt of the bed at the side of my raised beds. Then the plastic can roll down and tuck between the pvc and the edge of my bed, so I can lift them up easily to weed or harvest.
I wound a soaker hose around in my garden to water, so all I have to do is turn on the tap to water my plants. I don’t have to get access except for when I harvest.
I can also extend my harvest season by putting a few coaster-sized bits of wood in my garden when I plant it, and on those few exceptionally cold nights I light non-toxic beeswax candles inside my greenhouse to keep it warm overnight. Yes it’s a slight fire risk, but I have a xeriscaped yard with nothing near my beds, so if by chance my garden burned down, everything else would be okay. I also use this to start some of my greens earlier in spring, to get them through those freezing nights.
Karen says
I have spinach growing, but it has slowed down quite a bit. I am going to put one of these hoop houses over them. Will that help it to continue to grow, or just keep it alive until spring? I would like to harvest some more before then. I am in eastern NC.
dawn says
Does it matter which plastic you get. We have from 3mm to 6mm. Here in Texas I have strawberries growing n need to keep off the frost
Mavis Butterfield says
I’d say the heavier the better Dawn.
Malcolm Curbishley (England) says
Hi Mavis
Thank you for your very thorough and helpful tutorial for building a mini poly-tunnel
I’ve followed your superb guidelines and produced a small poly-tunnel for our vegetable patch her in the UK
One major change I made was to use 3 inch hinges to connect the four corners of the wooden frame
This allows you to dis-assemble the poly-tunnel and completely fold flat the wooden frame when not in use
Hope this idea helps you and others and thanks for a great website and tutorial
Cheers
Mac
Rich B says
Thanks for providing this tutorial. I was thinking about adding some lighting to extend the day during the short light months. Any suggestions on lighting types (I saw a mention of polycarb?). Àlso suggestions on how to install them?
.I am in Southern California and it can get cold at night during the winter as we do get an occasional frost and we our daylight during Nov.Through March is not long enough for tomatoes.
Rich B says
Great tutorial! I was thinking of adding lighting to extend my tomatoe growing season. Any suggestions on lighting and installation suggestions?
Jim says
Hi Mavis – brilliant idea – I am going to use it to construct a cat run – will use netting instead of polyethene
vela says
Also makes a great chicken run for snowy winter days
Greg says
Looks great and would be an easy build, plan on building one this fall/winter to start tomato and pepper plants in next February.
Lauren says
This is about the easiest (therefore BEST) way I’ve seen to do a covered bed. Bravo!
Pat says
Thank you for the great tutorial!