Fertilizer Effects on the Growth of Impatiens, Petunia, Salvia, and Vinca Plug Seedlings

Good fertilizer management is important in plug seedling production of bedding plants to prevent nutrient deficiencies and toxicities. We determined the effect of N, P, and K nutrition on the growth of plugs of impatiens (Impatiens wallerana Hook. f.), petunia (Petunia ×hybrida Hort. Vilm.-Andr.), salvia (Salvia splendens F. Sellow ex Roem.& Schult.), and vinca (Catharanthus roseus L.). For all four species, shoot N concentration was correlated linearly with shoot dry mass of the seedlings at transplant. Phosphorus or K concentration in the nutrient solution or shoot tissue had little or no effect on the shoot growth of seedlings, but shoot P levels increased with P concentrations in the fertilizer solution (luxury consumption). Salvia was the only species that also exhibited luxury consumption of K. Results of this study indicate that seedling growth of these species is mainly determined by N and this should probably be the main focus of fertility programs in the plug industry, while P and K applications can be reduced.