I found this article on Ebay this morning... Of all places!
GARDEN CLOCHES recycling Soda bottles
"A great way to use up those 2 litre soda bottles, and protect plants in your garden at the beginning and end of the growing season.
We live in zones 4-5 and this means that if I want to extend my gardening season I have to do it with either an expensively heated greenhouse, underground warming system or try my garden cloches.
These cloches are used to protect such plants as tomatoes set out and when there is a possible danger of a last frost. For us that means in April - mid May.
Take a 2 litre soda bottle, cut off the rounded bottom. To use - stake your plant. This is important. Then take the cap of the bottle and put the bottle over the stake. This stops the light weight soda bottle from blowing around in your yard.
The little bit of space at the top between the stake and the bottle can be plugged with whatever you have on hand. I use a piece of foil. I have been know to grab a bit of garden straw too to fill the gap.
Be sure to not leave this on all day, just at night. They can overheat just like a glass cloche will. If you know that you are going to have several nights of frost - this occurs especially near the end of the growing season, you can use a rock or wedge of wood to lift the cloche up from the ground to give the plant air cirulation during the day.
In the evening remove the rock or block of wood and put the cloche back down into the ground. This is a cheap effective individual greenhouse for our garden. You can use these for several seasons.
Good gardening!!
Guide ID: 10000000000702094Guide created: 01/20/06 (updated 06/11/07"