Abstract

We compared growth for plants 90 days from potting in 4 1 (# 1) nursery pots and growing outd oors in either peat moss: sandy loam: perlite (2:2:3 by vol) or peat moss : pine bark : perlite (1:1:1 by vol). Both media received the same nutrient charge and fertilizer treatments. During the 1985 season we applied weekly fertilizer levels of 0, 100, 200, 300, 400, 500, and 600 ppm of reagent grade ammonium nitrate, to which was added 125 ppm potassium chloride. During the 1986 season we repeated the study with fertilizer levels of 0, 400, 800, and 1200 ppm ammonium nitrate. For fertilizer levels there were significant differences in plant width, grade, fresh and dry weights and sum of fans—sum of fan diameters 2 cm (0. 8 in) above soil surface—both years with 400 ppm resulting in optimum growth. For media there were no differences during 1985, but there were significant differences for fresh and dry weights during 1986, and for root dry weight and fresh weight gain, with the highe st means from the soil-based medium.