APPLICATION OF GROWTH REGULATORS TO ORNAMENTAL SHRUBS FOR USE AS INTERIOR DECORATION

Around 1980 Dutch growers of woody outdoor plants started to sell their products at the flower-auction. Therefore, and because of the succes of Cupressus macrocarpa 'Goldcrest' asia potplant for interior decoration, people started to use ornamental shrubs in pot as potplants for indoor use. Screenings for performance indoors were started. The need for regulation of growth and/or flowering became evident and experiments with growth regulators on ornamental shrubs were started. Aspects of such experiments on Ceanothus rhyrsiflorus var. repens, Choisya cernata, Clematis 'Capitan Thuilleaux', Forsythia intermedia, Gaultheria procumbens and Pernettya mucronata, Hibiscus rosa-sinensis cultivars, Hydrangea macrophylla, Malus and Prunus cultivars, Pieris japonica, 'Debutante', Rhododendron (azalea) cultivars, Skimmia species, Vaccinium vitis-idaea 'Koralle', and Viburnum tinus are briefly discussed. Experiments with daminozide, chlormequat, and paclobutrazol on Rhododendron hybrids are reviewed in more detail.

It is concluded that regulation of growth and flowering of oranamental shrubs often offers good possibilities to grow them as a potplant for interior decoration, but that besides the possibilities several problems still exist.