Fayette Etter and Milo Paden both feel that the Broadview variety is self-pollinating, but even this variety may prove to be benefited by cross pollination.
The Persian walnut has developed in Pennsylvania and Ohio in a rather interesting pattern. Trees planted fifty to a hundred and fifty years ago managed to live and produce nuts. From these trees, seedlings were grown and planted by neighbors and friends. These trees and their seedlings in turn have now grown to producing age. Some few that produce good crops of nuts you hear about, but the vast majority are just non-producing shade trees. Until you look for them you little realize how numerous they are.
At Linglestown, Dauphin County, however, we find a striking exception to this. Here all the trees are productive. The question there is not why don't my trees produce, but is quite spirited as to who harvests the largest crop and best nuts.
About seventy-five years ago Alfred Kleopfer planted some Persian walnuts of unknown origin, but probably from Germany. He grew three trees which were planted, one beside the village blacksmith shop, one across the street, and the third at a neighbor's. One tree lived for only a short time. The blacksmith shop has been replaced by a modern dwelling but the walnut tree was saved and has grown to be a tree 6' 6" in circumference and probably 60 feet high. The one across the street is of nearly equal size but the top has been damaged by storm and the tree is not as tall.
These two trees were able to cross-pollinate and one tree was especially productive. Miles Bolton recognized its value and began growing seedling trees and distributing them to his neighbors. Some of them were quite skeptical and even refused to take them as a gift and plant them. However, he got the village pretty well planted to Persian walnut trees, so that today there are 145 nice trees within the village, and two small orchards on farms nearby.
Standing in the village square, one can see at least six Persian walnut trees higher than the house tops. Pollination is not a problem, and all trees are good producers. Young trees are in demand for planting, and seedling trees, coming up in the flower beds, compost piles, fence corners, and other places where squirrels have hidden nuts, are carefully transplanted to permanent locations.