Developing Production and Postharvest Protocols for Cut Penstemon grandiflorus 'Esprit'

The effects of production temperature and transplant stage on stem length and caliper of cut stems and postharvest treatments on vase life of penstemon (Penstemon grandiflorus) ‘Esprit’ were examined.  Plugs transplanted with 8–9 sets of true leaves had a longer stem length (64 cm) at harvest than those transplanted with 2–3 sets (58 cm) or 5–6 sets (61 cm).  Flowering time decreased as production temperature increased and when transplants had a greater number of true leaves.  The addition of 2% or 4% sucrose with 7 mg·L^-1 Kathon CG as a vase solution resulted in the longest vase life (9.4 d) of all treatments compared to the control (4.5 d).  Commercial holding solutions significantly increased vase life, while hydrators had no effect.  The use of floral foam or anti-ethylene agents, ethylene exposure, or sucrose pulses also had no effect on vase life.  Wet or dry cold storage of cut stems for more than one week reduced vase life.  Penstemon may be suitable for heated greenhouse production and has acceptable commercial potential as a specialty cut flower as long as a floral preservative (holding or vase solution) is used.