Clone selection of woody ornamentals in Finland

Fifty clones of the genera Forsythia, Hydrangea, Lonicera, Philadelphus and Viburnum were cultivated in comparative field trials at five sites in Finland in 1989-93. The aim was to find the hardiest and the most valuable clones to be recommended for landscape gardening. The evaluation covered about 30 traits which were recorded annually. Most attention was paid to winter-hardiness, resistance to diseases and pests, and ornamental value. The data were analysed using both statistical and non-statistical methods. A combination of these proved to be a successful method for selecting the clones with the highest value for production. Nine clones were selected as recommendable clones. The Hydrangea paniculata cultivars 'Grandiflora', 'Praecox' and 'Mustila' were found to be valuable and recommendable. Several Lonicera clones succeeded well and were renamed. Three clones were selected as being suitable for different purposes: L. tatarica 'Sanna suits well for hedges, L. x bella 'Dropmore' is white-flowered. and L. x bella 'Sakura' has a special growth habit. A true-to-type Philadelphus pubescens clone was renamed Tuomas' and an abundantly blossoming and hardy P. lewisii hybrid was renamed 'Tahtisilma'. Finnish Viburnum opulus clones representing a hardy type with plenty of blossoms were renamed 'Pohjan Neito'.