The Cliff England PDF scion list on his website only names Grimo twice. once on page 1 #9 “Grimo Manchurian Heartnut walnut” and page 34 #24 “Simcoe 8-2 Grimo’ s nursery, (GN) Heartnut walnut 2018”. Heartnut is mentioned several times but none appear to be grimo cultivars. Simcoe is sold by Grimo, but not a grimo cultivar, so maybe that second one is just listing it as the source.
it did. I cut it out
Scion wood alone is pretty useless for me. I don’t graft.