Hi there: I have 2 recently planted walnut trees. One is labeled "Persian walnut" which I assume is Juglans regia. The other is labeled "Cascade". Is cascade a subspecies? a different species? a cultivar? I thought Cascade was a type of Persian walnut? The cascade is not doing well, and I expect to need to replace it. I want something other than identical to the Persian for purposes of pollination. What choices exist? Can someone explain this to me? thank you
Persian Walnut is standard the English name for Juglans regia; that plant could be seedling-grown. 'Cascade' is presumably a cultivar of it, produced by grafting.
Will Juglans regia and Juglans nigra pollinate each other? or would I need another type of Persian walnut cultivar to pollinate Juglans regia?
Hybrids between the two are known. But that doesn't mean crossing of these is frequent and regular. However, do you actually need cross-pollination for cropping of walnuts?
Juglans regia is self-fertile: caveat is that it is sometimes only partially so. While both male and female flowers are on the same tree, the issue is one of timing between the two: sometimes they overlap, other times they are somewhat out of sync. To further complicate matters, as the tree matures the bloom periods of each tends to increase, increasing the odds of a good self-pollinated crop. So...you will get some sort of crop from the single seedling, but this could be diminished. Often, another seedling will most likely do the trick, though being seedlings with unpredictable bloom times, I suppose you could end up with two trees that remain out of sync...though this is unlikely. Only way to be 100% certain would be to do what you had before: another named cultivar known to be a good pollinator. As far as I know, juglans nigra will pollinate regia, given that hybrids of the two exist (one, called "Dooley 69" that I'm growing, has developed the superior attribute of a thin shell that you can crack by hand). As Ron says, though, this doesn't necessarily indicate a reliable pollinator...though perhaps a hybrid seedling would be more so.
