The 2012 ASHS Annual Conference

Rosemary (Rosmarinus officinalis), ‘Pink Lanterns’ columbine (Aquilegia canadensis), ‘Bath’s Pink’ cheddar pink (Dianthus gratianopolitanus), and ‘Rozanne’ cranesbill (Geranium ‘Rozanne’) were grown at different substrate volumetric water contents (Θ=volume of water ÷ volume of substrate) to determine the effects of Θ on their growth and morphology.  Two experiments were conducted; the first in the of fall 2011 and the second in the of spring 2012. Plants were grown at nine Θ: 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40 and 0.45 m³∙m^-3, which were maintained constantly using a capacitance sensor automated irrigation system. Generally, plants were visibly larger as Θ increased. Leaf count and leaf area of rosemary grown at higher Θ (>=0.30  m³∙m^-3) were twice as high as those of plants grown at lower Θ (<=0.15  m³∙m^-3). Shoot dry weight and fresh weight increased with increasing Θ. water availability impacted plant morphology, and thus the marketability of these perennial plants.