In the past a variety of rootstocks were used to graft plums onto including Myrobalan, Yellow Egg suckers, Marianna. In recent years St Julien A has become the usual rootstock for growing plums.
Compatible with nearly all plum, damson & gage varieties St Julien ‘A’ is of moderate vigour, reaching 3.5-5.5m (12-18ft). Ideal for most situations resulting in trees with fruit at a pickable height.
St Julien ‘A’ is a selection of St Julien which in turn is a sub species of Prunus insititia, a species which also includes the Damson, Bullace & Mirabelle. On its own St Julien will result in a shrubby quite thorny tree producing damson like fruits. Best to graft a nice plum onto it!