Plum Duo-plum Patio Standard Two plum varieties all on one tree! There are two varieties of plum on one tree, a compact tree will fit on your patio or balcony! This duo fruit tree is ideal for small spaces and make excellent container plants. Two varieties, Opal and Reine Claude d'Oullins, are grafted onto one stem to create a perfect partnership which will pollinate each other to produce good crops, despite being dwarf trees, the fruits will be a normal size.  Grown in containers, these dwarf trees will reach a mature height of just 1.5-1.8m.