I noticed you listed skirret’s hardiness at zone 6. I have been growing skirret in Zone 5a for over 29 years. Kingwood Center is a garden estate open to the public in Mansfield, Ohio

Thanks for the info, Glenna. I put it at zone 6 because I was able to kill skirret in a freezer at 0 degrees F, which corresponds to 6b. I figured that it would probably survive a few degrees colder in the ground, so I recommended any zone 6. Hard to test it here. I will adjust our growing guide accordingly.