I use it under my squash & seems to work great. In march the soil is cold and I thought it might warm the roots a bit .
To me the only justification for using it would be if you have a really heavy, clayey soil that stays cold for a very long time in spring. It would be important, however, to remove it as soon as the soil warms up, especially in your normally rainy climate. Myself, I would wait a little bit for the soil to warm up rather than bothering with the cloth. If you want your plants to grow fast and strong, make your soil healthy and fertile and they will be able to make up quickly for a small delay with spring planting. I wonder, for how long you use the cloth already under your Squash? Just last year or longer? In the short run it may look like it works well, but it is harmful to your soil ecosystem and so is detrimental to the soil fertility in the long run. Is your garden organic? As Genevieve Schmidt from the North Coast Gardening - Gardening in the Pacific Northwest puts it: "One of the biggest barriers to organic gardening success, and I mean that literally, is landscape fabric." I agree with her entirely in what she writes about the stuff here.
