Growth of Impatiens ‘Accent Orange’ In Two Compost Products

Growth of Impatiens wallerana Hook. ‘Accent Orange’ was compared in two compost products made of biosolids and yard trimmings but differing in final particle size. The first product was screened to pass a 19 mm screen while the second product was screened to pass a 13 mm screen. Treatments consisted of 100 percent compost or substrates in which compost was combined with control substrate components at 60 percent, 30 percent, or zero percent compost. Shoot dry mass and size increased linearly as the percentage of each compost product in the growing substrate increased from zero to 100 percent. Final substrate electrical conductivity (EC), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) concentrations also linearly increased as the percentage of each compost product increased in the substrate. Final plant size and shoot dry mass were significantly greater in the 13-mm product than in the 19-mm product. However, both the 13-mm and 19-mm products at 100 percent produced larger impatiens ‘Accent Orange’ plants compared with plants grown in zero percent compost.