Container Plants: A Comparison of Organic and Inorganic Fertilizers

This study was initiated to determine if herbaceous ornamentals would have differences in growth when fertilized with commercially available organic fertilizers and commercially available inorganic fertilizers applied at label rates and at equal nitrogen rates . Four comparisons were made: (I.) commercially available organic fertil izer at label rate - - nutrient solution at equal analysis and rate, (2) commercially available organic fertilize rate label rate--commercially available inorganic fertilizer at label rate , ( 3 )comercially available organic fertilizer at 285 mg nitrogen per month--commercially available inorganic fertilizer at 285 mg of nitrogen per month, and (4) a comparison of ommercially available organic fertilizer applied at label rate to a soil mix and to a soil less mix. The study was conducted a t Longwood Gardens' experimental greenhouses and at the University of Delaware from January to April 1976. The plants studied were Coleus 'Glory of Luxembourg', and geranium, Pelargonium hortorum 'Cherie'. Fertilizers studied were cow manure (2-1-2), fish emulsion (5-1-1), a mixture of organic fertilizers (4-5-2), a dry chemical fertilizer (8-8-8), a liquid chemical fertilizer (15-30-15) , and a slow release fertilizer (12-6-6). Commercially available inorganic fertilizers applied as directed on the label were found to produce plants with more vigorous growth, more attractive appearance and greater dry weights than commercially available organic fertilizers applied as directed. fertilizers also produced more growth when the fertilizer label rates were increased to equal nitrogen levels. The inorganic The inorganic fertilizers seemed to have analysis ratios that were better suited for promoting abundant plant growth. both organic and inorganic fertilizers resulted in Increasing the "potted plant" label rate of both organic and inorganic fertilizers resulted in improved growth and greater dry weights. Advisor: Charles Dunham, Richard Light