A study was conducted to investigate the effects of nighttime temperatures on offset formation in hosta, and determine if benzyladenine (BA) can overcome potential detrimental effects of high temperatures. Stock plants of two cultivars, ‘Francee’ and ‘Frances Williams’, were divided, potted, and allowed to establish. When roots had reached the substrate-container side interface, half the plants of each cultivar received a foliar spray application of 3000 ppm BA. Plants were immediately transferred to growth chambers programmed for a 12-hour photoperiod at 32C (90F) and a 12-hour dark temperature of 12.8C (55F), 18.3C (65F), 23.9C (75F), or 29.4C (85F). Plants grown at the three lower nighttime temperatures produced more offsets than plants grown at the highest nighttime temperature, but only when treated with BA (both cultivars) or in ‘Francee’ (±BA). Plants treated with BA formed more offsets than −BA plants and ‘Francee’ produced more offsets than ‘Frances Williams’, but only at the three lower nighttime temperatures. Across nighttime temperatures, both cultivars produced more offsets when treated with BA, and ‘Francee’ produced more offsets than ‘Frances Williams’, but only in the presence of BA. Whole plant growth index decreased as nighttime temperature increased, and generally was lower for ‘Frances Williams’ than for ‘Francee’. Plant quality or stage of offset development was not affected by nighttime temperature
5Professor, Department of Botany-Microbiology.