Yep, and I’m trying to preach all the time to pot up your rootstocks a year in advance no matter what it is and/or establish them in-ground & then graft. I’m going to have awesome persimmons to graft on this coming winter thru Spring that are well-rooted in 14" x 2.7" Stuewe Deepots. That size Deepot also lays flat and at the right height for my Hot Callus Pipe DIY I lay on my concrete basement floor in complete darkness.
If you’re going to graft nut trees in the 1/4" range, a hot callus pipe will make all the difference in the world.
Hot callus pipes were designed for denser wood tree species which will always take more time to callus than softer wooded trees/shrubs. oak, & hazels are common hardwoods done on callusing benches. Certainly all nut trees, included…
I was enlightened that folks in the south (Texas anyways) don’t have basements due to high water tables, and therefore wouldn’t be able to use hot callus devices. I think you guys surely could use them if you kept it off the ground such as on a work bench in your garage & even if you have to construct a temporary frame to keep the inside area dark during callus.