mtgarden gal
Senior Member
Posts: 123
Joined: Thu Apr 07, 2011 5:46 pm
Location: Southern Montana

building a small portable greenhouse

Hi, one of my projects I want to do this summer is to build a small portable greenhouse. All I want is something with 4 or 5 large shelves on wheels so I can roll it from place to place. One of my questions is: what type of plastic do I use to cover it?
What is an easy way to vent it?
any other tips on small greenhouses would be appreciated. I've never used one before. Thanks!

User avatar
digitS'
Super Green Thumb
Posts: 3582
Joined: Sun Sep 26, 2010 5:10 pm
Location: ID/Wa! border

If you use construction grade plastic film, it won't last from one season to the next. I used to say that plastic like that would fall apart in October and it didn't matter when I put it up. Almost true - it just can't take the summer sun.

The UV-resistant plastic film that you can buy from Farmtek or other sources, just isn't that expensive if you can expect it to last 4 years or longer.

I'm not sure how much rollers would help. Something made out of plastic film, using 2" by 2" framing and without a floor is very, very light. Maybe I don't understand what size you are wanting. Is it something that you can walk into? Would it have a floor?

Some method to keep the thing from blowing away is important almost no matter what the size. My protected growing structures are requiring some attention today because of 25mph gusts but with temperatures in the low 50's and plenty of sunshine. They aren't in danger of blowing away but the air is a little cold while the heating inside is substantial.

Ventilation should be as high as possible for days like this. You want the hot air that builds up high to exit and cool air to stay, mostly, up off the plants. With vents near the top, that is more-or-less what is happening.

Please let us know more about the dimensions.

Steve
We are each other's harvest; we are each other's business; we are each other's magnitude and bond. ~ Gwendolyn Brooks

mtgarden gal
Senior Member
Posts: 123
Joined: Thu Apr 07, 2011 5:46 pm
Location: Southern Montana

"greenhouse" was possibly the wrong term. I want it to be maybe 5-6 feet tall, 3-4 feet wide and maybe about 1-2 feet deep. I want the whole front to be a door that swings open for access. This isn't a greenhouse you'd walk in to. Just a portable "seedling sprouter/greenhouse type of thing that I can roll inside or out depending on my needs.
I envision being able to hang my grow lights from the underneath part of each shelf so each shelf has a light hanging above it (if that makes sense). These lights would be removeable by hooks to use or take out as needed.
So this would be something that if the weather is bad I can easily move it into the house or garage.

Can you give me some examples of how warm it is in a greenhouse compared to outside temp? if it's 40 degrees and sunny outside, what will it be in the greenhouse?

Thanks!

User avatar
digitS'
Super Green Thumb
Posts: 3582
Joined: Sun Sep 26, 2010 5:10 pm
Location: ID/Wa! border

MTGarden Gal, I'm not really the best person to comment. I have never had a greenhouse smaller than about 5' by 16'. Of course, I see the advertisements for greenhouses that are the type you are thinking of.

I often set up small tunnels of about 4' by 8'. But, those are very low and with a lot of exposure to the soil/lawn.

With an exhaust fan running and a vent open in the opposite wall, the temperature in my current greenhouse (180 square feet) was up to 75° with 53° fast-moving air, outdoors. Without the exhaust fan and just 2 vents open, it would probably been closer to 85°. It could have been more open to the outdoors however, if I'd open the door. With so much wind, that would allow too much cool air in, however.

One of very small size will probably both heat and cool quickly.

Steve
We are each other's harvest; we are each other's business; we are each other's magnitude and bond. ~ Gwendolyn Brooks

Return to “Vegetable Gardening Forum”