GROWTH AND ADAPTATION POTENTIAL OF FLOWER ING ORNAMENTAL SHRUBS UNDERCLIMATIC CONDITIONS OF QUEBEC AND NORTHEASTERN ONTARIO

Seven flowering cultivars of deciduous shrubs were evaluated for their winter hardiness and their growth potential to provide adequate recom mendations regarding their adaptation to different climatic conditions . Plants were grown at eight sites in Quebec and one in northeastern O ntario in order to cover three broad biogeographic regions. Hydrangea paniculata 'Grandiflora', Kerria japonica (L.) DC., Potentilla frutico sa 'Goldfinger, Prunus x cistena N.E. Hansen, Prunus tomentosa Thunb., Viburnum opulus 'Compactum' and Weigela hybrida 'Brystol Ruby' were u sed. Potentilla and Viburnum were not affected by winter conditions at any of the sites, whereas Hydrangea, Kerria and Weigela did not survi ve at Kapuskasing. Our results indicated that Weigela was adapted to z one 5b only, whereas Kerria should not be recommended in any zone test ed. Although the other species were adapted throughout Quebec, their p roduction was superior in the Montreal region. Annual pruning of Kerri a and Weigela was related exclusively to winter damage. For the other species, pruning is related to winter, rodent and mechanical damage.