I am in zone eight (western oregon)
In January I opened my cold frame (nothing inside) for several weeks. Later I noticed bachelor buttons sprouting behind the frame and have come to realize that the sun shining thru the thick glass heated the soil.
Well, owing to the fact we still faced cold weather, I dug up many and put them in the cold frame (with the door closed) and they have done very well. Many are 4-6" tall and very vigorous.
My question is: "How frost resistant are these starts?" I want to relocate them in my garden. We will still have a few mornings of semi-heavy frost and I don't want to lose them.