Organic Fertilizers for Greenhouse Production of Day-neutral Strawberries

Organic, locally produced strawberries are in high demand and greenhouse production can help meet consumer need for fresh berries, particularly in the extended off-season of northern climates. Organic fertility amendments require some microbial breakdown before nutrients become available, and little data exist on organic fertility recommendations for day-neutral strawberries grown in greenhouses. The affect of fertility on nutritional composition of the crop is also of interest in these systems. Our objective was to investigate a variety of organic fertility sources on day-neutral strawberry (Fragaria x ananassa ‘Albion’) plants grown in a gutter system in the greenhouse. The fertility sources were: 1) fish emulsion, 2) poultry litter, 3) all-in-one potting mix with compost, 4) a custom mix of peat, vermiculite, leaf litter compost, greensand, rock phosphate, blood meal, and lime; and a conventional fertilizer comparison. We measured yield, runners and flower production, vitamin C content of fruit, and the nutrient composition of the media was measured at planting and harvest. Results show that the poultry litter treatment significantly out yielded the other fertility treatments. The custom mix tested high in soluble salt concentration, resulting in low yield. Vitamin C content was highly variable, ranging from 35-88 mg/100g fw but did not significantly differ by fertility treatment. Flower number was highest in the all-in-one potting mix with compost and lowest in the custom mix and fish emulsion treatments. This experiment shows that ‘Albion’ strawberry plants respond differently to organic fertility sources and contributes to our effort to maximize yield and improve quality of organic, greenhouse grown strawberries.