Cold Frame Coverings

by Gregory
(Livonia,MI)

Can I use 4M polypropylene copolymer twin sheets for my cold frames? I only see polycarbanate sheets being recomenned. polypropylene copolymer twin sheets are used in sign making and is rigid, for a 4x8 4m sheet is only $15.00.


Doug says he's not a chemist nor do I have any experience with this material. The main question I'd have is whether this is UV stabilized. If not, the lifespan will be very short and you'll wind up with plastic shards and dust on the first cold snowy or ice storm day. It will last one summer and that will be the end of the story.

The amount of light being transmitted determines the use of the cold frame. If you're using it for germination and propagation, then low levels are no problem. If you're using it for actually growing things (particularly during low light months) then you're going to find a percent or two less of light going through is going to make a huge difference to how much growth you're going to get. So the translucent quality is important based on your cropping.

If it's for a home scale cold frame and you don't care about how much you get out of it - then this isn't a factor either.

You also have to check out cold tolerances to cracking. If this material becomes brittle or more rigid under cold stress, then ice storms (you're in Mi after all) will crack it.

And finally, off the top of my head, you have to know the lifespan under all these conditions in combination. And the differing quality of the material.

What has been clear in my experience with greenhouses is that if this material was already used in the industry, I'd run with it. But if it's not being used, then there are some problems with it being used in horticulture. You'll have to figure out what the data is and the answers to the above questions.

That's my honest take on greenhouse coverings. Sometimes a penny saved isn't a penny earned.

You might also want to check out the section on greenhouses on my other site right here.