I’m thinking if I had a pollination problem, while Court Pendu Plat and the like would be great experiments, I’d probably graft one or two late blooming crabs and be done with it.
ETA: This website may be of help to you.
http://www.northbranchnursery.com/rc/tree-guide/crabapple-bloom.html
In looking back on this thread, your mention of Northern Spy needs the caveat that it is a tardy bearer. It takes several years longer to begin blooming than the average apple cv. Nevertheless, those who have it hold it in high esteem.for several uses, as I understand it. (Fresh, pies and cider base.)
OK, this is a bit tongue-in-cheek, but had to show the unexpected result of transplanting Redfield this season. It was moved while dormant last spring, but apparently needed some time to settle in. This photo was taken yesterday, August 23. Yep, debut bloom - and beautiful, I think. Let’s hope it settles into a more normal time frame next year!
