Hi Cheryl! Welcome to NGA.
I looked up the common name in our plant database, and the few that I spot-checked all listed "5a" as their minimum cold hardiness. So they should be happy as clams, once established.
But, like Philip, I would guess that the babies are more tender.
>> My question is should I plant them in the ground or in my raised bed
Sorry, I don't really know.
But lately I've been reading that "they" think it's often better NOT to plant large trees in an improved planting hole, because the roots NEED to spread out many yards in all directions, but may never leave the hole if the soil there is TOO inviting and the rest of the yard is clay.
If the raised bed is large enough that it will hold the entire tree's roots years from now, cool!
>> and put a cold frame over them for the winter?
My GUESS is that some temperature protection might be a good thing, especially during cold spells. But be sure to leave some ventilation or open it up every morning, so you don't get one clear, warm sunny day that makes it think that Spring has Sprung.
Once the soil gets cold, you might make the mulch over its roots extra-thick so the young root-ball doesn't feel a lot of cold/warm cycling and frost heaves and dehydration.
