the very base understock is green leaf Prunus cerasifera, and to it, was grafted a purple-leaf ornamental P. cerasifera, and then unto it I grafted Hollywood plum (P. salicina) and the one on the top are various kinds of European plums, P. domestica. Sometimes on one limb, I have about 7 different kinds of cultivars connected one after another to form the limb… grafted along the way as the tree grew. The tree is now 9 years old. I now realized I wasslacking oiff… only 7 in one limb after 9 years.
We are in an area that sometimes receive marginal chilling hours, so I have to be creative to make the multi-grafted tree bear much fruit, even with high-chilling hours cultivars. I grafted the high chilling hours, particularly the European plums on the top because frost formation always starts at the top of the trees. meaning that they will receive more chilling hours than the ones below. Moreover, the European plums are among the last ones to wake up from slumber… So by grafting on the top, they’re assured of receiving sunlight and not shaded out. They are also grafted on the south side of the tree for the same reason that they’re the last ones to leaf out, so they won’t be shaded by the others.