353 Organic Nutrient Management of Greenhouse Production of Edible Flowers in Containers
Eight species of edible flowers were grown in 12.5-cm (1.5-L) square containers during the months of November through May, in a root medium suitable for organic certification or a standard peat and perlite mixture with preplant fertilizer. Plants were fertilized with 200 mL of either a water-soluble fertilizer (19–1.8–19) at 300 ppm N, fish emulsion (5–0.4–0.8), or a certified organic, commercially available soluble fertilizer (6–2.6–5), each at 300 or 600 ppm N applied every 2 weeks. Shoot fresh and dry weights were measured and percent dry weight was calculated. The fresh weights for all species were highest for plants fertilized with the organic fertilizers. For all but one species the organic fertilizer treatments had the same or higher dry weights than the inorganic control. The percent dry weights for all species were the same or higher for the inorganic control treatment. The effect of the organic fertilizer rate on the dry weight was species-dependent. The highest flower production generally occurred with 300 ppm N. Flower size was measured for Viola tricolor and Viola ×. wittrockiana species. For both species flower size was smallest for plants fertilized with the 600 ppm certified organic fertilizer. Root media pH and EC were tested at 6-week intervals throughout the experiment. In general, the pH increased from the first to the second sampling date, but only increased or decreased slightly for later dates, and there was little effect of fertilizer type. Root media EC decreased initially with minimal change later.