Clear trash bags as mini-greenhouses
 

Has anyone tried using clear trash bags as mini-greenhouses. I've set up my stakes and cages but it's still early for planting tomatoes in Massachusetts. A simple way to cover the plants would be to pull clear trash bags over the cages. Has anyone tried this, has it worked? The coldest temperatures that I expect in the next few weeks is around 39.

It's a good idea for wind protection. You'll want the tops open, though, or else it will get too hot inside.

I wrap the cages with bubblewrap when I plant early and my plants outgrow the walls-o-water -- it's a little sturdier in the wind and rain than plain plastic. I get it on freecycle.

When temperatures below 45 or so are forecast, I've found the most important thing is to have the top covered, because if early morning dew lands on the leaves, it may freeze (if it gets cold enough). So I have a gap between the bubblewrap and the "roof" (=another piece of bubblewrap, a piece of screen, or a plastic bag). That way, air can flow through, but the plants are protected from dewfall and wind.

The main issue is usually night time temps, which a bag won't help with and I would think you would be asking for mold/fungus problems with high humidity during the day and cool at night.

I agree that if if you try it, either open the tops or make sure there are some good sized holes in the side to let out excess heat and humidity.

I live in Seattle, where it is still cool too and I don't like to put plants in the ground until the end of May, but if I wait too long I won't get any fruit.

I second the wall of water route, an old standby and a good option. You can buy them in 3 packs on-line for about $10.

I was also wondering how well a couple layers of bubble rap would work, and it is good to see somebody else has had success with that!.

But the big issue with any of these approaches is that plants are still in the cold soil and if you get a cold snap that lasts for more than a night or two, you could be in trouble.

I have successfully used them as covers before. But only temporarily. Take them right back off as soon as the cold snap passes.

In the past I have used painters visqueen plastic with fantastic results.
You can get a large roll for around 15.00.

You can then cut it in the size and shape that will work for you.

Thanks for the responses
 

I'm going to give it a try after I put my plants in the ground on Sunday. In the mean time I'm taking them inside at night and putting the outside in the morning. It's been in the 60s during the day, dropping to the late 30s at night. Hopefully by next week it will only be in the 40s at night so the bags should be sufficient.