On 25/05/2018 14:27, Roger Tonkin wrote:
I am wondering about a mini-greenhouse to grow tomatoes in, but
most of them seem to be green plastic - why? Is it better than
clear, or stringer or what?


You get what you pay for.
Commercial poly tunnel covers now last anything from 5 years to well
over 10 years.
You might be better to build a wooden frame and cover with mini profile
plastic sheeting such as Wickes Mini Profile Corrugated Sheet this has a
10 year life.
If you build it against a wall you can fasten the frame to the wall so
it won't blow around.