Mine made it through their first Winter with -28 as a low temperature
with only an inch of crusted snow for protection. Each plant is producing
only a handful of berries that didn't start ripening until after other
blackberries were played out.
Jim Fruth
Brambleberry Farm
Pequot Lakes, MN 56472
For jams, jellies & syrups:
www.bberryfarm.com
(877)265-6856 [Store]
(218)831-7018 [My Cell]
Sorry, my long-term memory was off by a zone, it was 4, not 5. I quote from
the "Growing Instructions" I received with Doyle Thornless plants in 1999:
"In zones 3 and 4, plants should be protected, at least, during the first
winter"
To me, that's not hardiness for zones 3 and 4, and therefore doesn't satisfy
the "all 50 states" as had been claimed and as had been in my purchase
decision parameters. Unprotected vines have never survived the winter for me
here.