Heat Tolerance of Annual Cultivars in Zone 8

Abstract

In the summer of 1995 and 1996, 245 and 400 annual plant cultivars were evaluated for heat tolerance and landscape performance. Nine transplants of each cultivar were installed in raised beds amended with controlled-release fertilizer as per soil analysis recommendations, under full-sun and overhead irrigation, at the E.V. Smith Research Center in Shorter, Ala. (lat. 32° 30′ N, long. 85° 40′ W). No mainte-nance, with the exception of one midseason pruning of petunia, was performed on any of the cultivars. Catharanthus roseus 'Blush Cooler' was the best performer in 1995 with a mean rating of 4.1 (of 5.0). Salvia farinacea `Victoria Blue' and Petunia ×milliflora `Fantasy Pink' performed well, with a mean rating of 3.5. In 1996, the cultivar with the highest mean rating was Gomphrena globosa `Lavender Lady' (4.1). Second highest was G. globosa `Strawberry Fields' (4.0). Other cultivars that performed well in 1996 and had high mean ratings were Verbena × speciosa `Imagination' (3.6) and Melampodium paludosium `Derby' and `Medallion' (3.5 and 3.5).