But it really works better putting it around the inside of tires to maximize the growing season. Here is how I do it. The first step is to spray the inside of a clean cut truck tire with 3M super 77 contact spray.
Then I line the inside with heavy duty tin foil and smooth it out as best I can.
I also do the tire lid. It will help reflect light back down onto the plants. The white fabric covering the centre of the tire is agricultural fabric. It lets the light and rain in. I can also use plastic but if you do you have to be very careful not to let the plants burn. Its glued on with acoustic sealant, a messy black stuff that doesn't harden.
The reflector " riser " tire gets put over the ones with soil in it and the reflective lid goes on top. I have drip irrigation that waters the plants. The temperature in the tires was close to 33C yesterday. Maybe a little to hot but the average temperature is rapidly falling despite the fall heat wave.
I am doing an experiment here with some Chantilly carrots . I want to see how long they will actually grow for. Last year we did a similar experiment, without the tin foil lining and we had plants growing in October. Just like little mini green houses.