153 Garden Performance of New Guinea Impatiens in Sun and Shade

Abstract

The New Guinea Impatiens (I. hawkeri Bull.) has become one of the most important spring crops for many growers. Rapid and continuous development of new and improved cultivars have lead to tremendous diversity in flower color, leaf color, plant size, and growth rate. Penn State has conducted large-scale garden evaluations of New Guinea Impatiens since the mid-1990s. Each cultivar is evaluated in both the sun and shade for uniformity, flowering, foliage, and overall growth and form. Ratings use a 1 to 5 scale with 1 being unacceptable, 2 = poor, 3 = fair, 4 = good, and 5 = excellent. Height, width, and flower size are measured in August. One hundred fourteen cultivars in 15 commercial series have been in the trials for two or more seasons. There are significant differences in the performance of cultivars and series in the trials. `Celebrette', `Paradise', `Pure Beauty', `Celebration', and `Riviera' were the top-performing series. Within each series there were outstanding cultivars and others that did not perform as well. Plants performed better in the shade than in the sun. The average rating for plants grown in the sun was 3.3 while the rating for shade grown plants was 3.8. New Guinea impatiens were shorter (11 vs. 12.3 cm), spread less (18.9 vs. 22.1 cm), and had smaller flowers (4.8 vs. 5.3 cm wide) in the sun than in the shade, respectively. There were no significant interactions between sun vs. shade, and cultivar or series.