EVALUATION OF GROWING MEDIA COMPONENTS FOR PHALAENOPSIS

Abstract

Several growing media containing pine bark, coarse slightly decomposed peat, peat fibres, coarse wood fibres, sphagnum moss or coconut husk chips were compared as potting mixes for Phalaenopsis 'Pauline'. The eight different growing media were amended with 0.5 g/L of a water soluble complete fertilizer (N+P 2 O 5 +K 2 O+MgO = 15+10+15+2 plus micronutrients) and adjusted to a pH (CaCl 2 ) of about 5.5. During the cultivation period, all plants were fertilized weekly with 50 ml of a standard nutrient solution containing (mg/L): 105 N, 15 P, 88 K, 9 Mg plus micronutrients. Additional nitrogen was added in all treatments except for 100% sphagnum moss, at a total rate of 120 mg N per plant, given in seven parts from week 9 to 15 after potting. Good or adequate quality plants could be produced in all tested growing media. There was no effect of the growing medium on plant size except for mixtures with coco chips, in which the plants remained smaller. The growing medium had a clear effect on flowering traits. Plants cultivated in mixes containing coarse wood fibres developed an equally high number of flower spikes and flowers as plants cultivated in the standard mixture of 70% pine bark and 30% coarse peat. Plants in mixes with coco chips had significantly less spikes and flowers whereas media containing sphagnum moss showed equally high numbers of flowers, but fewer spikes than plants in the standard mixture. Plants grown in mixes containing wood fibres or sphagnum moss had a well developed, superior root system.