ESTIMATION OF RHODODENDRON FLOWERING INTENSITY IN BOTANICAL GARDEN OF SIAULIAI UNIVERSITY DURING 2003-2007

Historically, rhododendrons (Rhododendron L.) have rarely been planted in Lithuania landscapes due to lack of knowledge about their cultivation and due to complicated adaptation. However, nowadays rising interest in rhododendron might be caused by increasing investigates in adaptation and cultivation of these plants. One of the main requirements for ornamental woody plants is the quality of flowering. Specifically flowering intensity should be seen as the most important criterion of ornamental quality was evaluated. Flowering intensity was evaluated in view of abundance of flowering. Methods that have been verified by long-term investigations were used to estimate the intensity and duration of flowering for rhododendron cultivars in the Botanical Garden of Siauliai University. Usually the collection evaluate using the five main criteria: (1) general condition; (2) resistance to low temperatures; (3) flowering intensity; (4) phytopathological condition; (5) suitability for cultivation in green plantations. Data collected during 2003–2007 demonstrate that the majority of rhododendron primary bloom occurs from May (the third decade) to June (the third decade). The majority (64%) of the cultivars in the collection flower abundantly (3 points). Reasons for poor and uneven flowering of rhododendrons might be the freezing of flower buds during late spring frosts. For some rhododendron cultivars growing in the Botanical Garden, repeat flowering is typical. Second bloom as is customary started in August and lasted until the middle of September. After comparing primary and repeat flowering, we found the second bloom to be less intensive, although the duration of the repeat bloom was approximately the same as the primary bloom in the spring. The research initiated by the Botanical Garden will help the landscape industry and consumers to select rhododendrons that are suitable for cultivation and can abundantly flowering in Northern Lithuania.