Top-grafting is the method of creating a fruiting or ornamental plant by grafting one plant with desirable characteristics onto an upright stem of a different plant. In fruit trees it can produce good quality, quick fruiting trees relatively cheaply and in ornamentals it can produce interesting miniature trees with a weeping or rounded form. Among the most popular top-grafted trees are weeping forms of willow such as Salix caprea ‘Pendula’ and Salix alba ‘Tristis’. Popular top-grafted shrubs which give the ‘lollipop’ form are Syringa meyeri ‘Palibin’ (Korean Lilac), Salix integra ‘Hakuro NIshiki’ (Flamingo Willow) and Ceanothus ‘Victoria’. There are also many top-grafted forms of roses.
These mini trees certainly look chic at either side of a front door or on a patio but they do have their problems, including a propensity to sucker at the base. These new growths will not be the same as the plant you thought you had bought. This is because the stem plant (or rootstock, as it is known) was selected for its straight trunk, not the weeping or rounded form of the plant on top (or scion, as it is known). However, if the plant on top (the scion) was not grafted on to the stem plant (the rootstock) it would not grow tall and probably just scramble around the soil surface. Such is the art of grafting ornamental plants.
Branches can also grow from the trunk itself and these, too, will not be the same form as the plant on top. These are technically called water shoots rather than suckers.
However, do not fear if your beloved ‘lollipop’ standard is sprouting these types of shoots. Simply prune off the unwanted growths. Use secateurs to cut and growths from the trunk close to the junction point or cut to the base for suckers. There is no particular time to carry out this task. When you see an unwanted shoot, remove it.
If you do not remove suckers and water shoots, they will eventually overwhelm the ‘lollipop’ or ‘weeping’ tree as they are normally faster growing and more vigorous than the plant on top (the scion).
So, if mini trees float your boat then be vigilant and look out for those growths coming from the rootstock or your mini tree will soon become a large shrub.