silly novice ?

Can you take cuttings of the hibiscus roots to start new plants in the greenhouse overwinter?

Good question - I'm curious to see what reply you get. I do know some hibiscus are sold as bare root but usually it takes forever for it to grow! My sister tried that once and swore she wouldn't ever try it because it took almost 2 months before she even saw any sign of life!

I don't know about taking cuttings of the roots, but you can take regular cuttings of the plant and that should work fine.

I had to dig some to move them and they have great lateral roots at least 4 ft long......thinking about chopping some off and trying to make new plants

It can't hurt to try, it's definitely not the most common method for propagating hibiscus, but you really don't have anything to lose by trying (besides some of your time of course!)