The North American species H. arborescens is not particularly attractive and is usually seen only in scientific collections. However, the various forms and named varieties which have been developed from the species, the so-called ball hydrangeas, have long been grown in Finland.
The best-known of these varieties, ’Grandifolia’, was found in the wild in Ohio in the year 1900; it has ball-shaped double blossoms about 10-18 cm in diameter. ‘Annabelle’ is another variety of wild origin, having been found near a town in the state of Illinois called Anna. This variety has showy inflorescences which can be over 20 cm in diameter.
These ball-hydrangeas are generally considered rather winter-tender. At Mustila, they grow more or less as perennials, the tops freezing each winter. This is not a problem regarding flowering since the flowers form on the new growth each year. In gardens and parks hydrangeas are usually cut down to ground level every year. A reasonable number of branches guarantees large blossoms.
The naming of these various tree hydrangea varieties has become rather confused though ‘Annabelle’, with its enormous blossoms, is usually easily distinguishable.