Four large cranberry cultivars were grown in artificially prepared peat solum obtained from highmoor peatbog. Nitrogen and potassium fertilizers were applied at 10 and 20 kg of each element per hectare. Nitrogen was applied as ammonium sulphate and potassium as potassium sulphate in equal doses during the leaf-bud break, hook stage, fruit set and bud formation. Plant phenophases, the number of fruit-bearing shoots per 1 square meter, the number of flowers per 1 fruit-bearing shoot, the number of set berries per 1 fruit-bearing shoot and the volume of the yield were investigated.It was revealed that the American cultivars of the large cranberry may be successfully grown on artificially prepared peat solum obtained from highmoor peatbog. In the climatic conditions of north-eastern Poland, flowers of the earliest cultivar ‘Ben Lear’ were damaged by springo frosts. Nitrogen and potassium fertilization did not affect significantly the course of phenophases and plant morphology, but had a positive effect on yielding. The most favourable dose was 10 kg N and 10 kg K, particularly for cv. ‘Pilgrim’ and ‘Stevens’.

Keywords: large cranberry, nutrition, cultivars, phenophases, plant morphology, yielding