flowerbug
Garden Master
Not as easy as it sounds. The roots may indeed winter over where the ground does not freeze; but they are not as substantial as bulbs, and delicate. I noticed that my Aeron Purple Star roots a couple years ago were noticeably large, so tried to lift & winter over some of them. Although the area below the stem was swollen, many of the larger roots were very fragile & broke off easily during extraction.
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Despite my best efforts, those roots did not survive my long winters. In retrospect, had I planted them in pots mid-Winter, they might have survived... I may try that one of these years. The roots also might have better chances of survival where the ground is only frozen for a short period; but chances are that most of those areas would also be too hot to grow runner beans successfully.
i've never seen pictures of those before! neato!