Second, the answer is mostly "No". The warmth will help the plant to grow is cooler climates, but can cook a plant in hotter ones. It does not "magnify the light", it just holds in the heat and makes a solar oven or green house. Since you are in a maritime climate, it might be OK for you.

Also there is the problem of moisture- leading to mildew and mold. Not good. And the build up of oxygen isn't good either. You would have to remove the bag frequently to avoid these problems.

Now if you had it set up so you could easily remove the bag during sunny hours and replace it at night, then it might be worth it. It would act as a mini-greenhouse.

I used to live on the Pacific coast and everyone marveled at my tomatoes. I grew them next to the south wall of a garage. I took 2 x 4s and used them to make a triangle against the garage and tacked clear plastic over it. The garage acted as a heat reservoir and kept the greenhouse warm late into the night. The tomatoes LOVED it. I imagine cannabis would love it, too. (One of these days, I gotta do that...)

-Granny:hippy: