Do they blow away?

In a word…No.  Most people tend to think of a polytunnel as a glorified tent, ready to blow away at the first sign of a breeze. Commercial growers can’t afford to have their polytunnels damaged by weather so they’re built to withstand the most extreme conditions. As long as the construction instructions are correctly followed, no problems will occur. For very exposed sites, we would recommend also using base rails (this helps achieve a tight cover), crop bars and storm stay braces.