Hardy begonias: the next generation

In a previous post (Beyond Begonia grandis: new hardy begonias), I discussed several begonia species and hybrids that have been around for a few years and were already known (or purported) to be fairly hardy.  In this post, I'll discuss a new generation of begonias I've discovered to be hardy in my zone 7a/b garden in just the last few years, even though some of them have been around much longer than that!

Hardy begonias emerging

Begonia pedatifida showing creeping rhizome and new growth

To most gardeners, "hardy begonia" means Begonia grandis, a tuberous species from China that for years has been considered the only reliably hardy member of this huge but mostly tropical and subtropical genus.  That has changed as recent collections in China have turned up a number of rhizomatous species that are also fairly hardy.  I'm trialing several of these in my zone 7 garden (see But where are all the begonias?) and some of them are already emerging after my area's coldest winter in 20 years.