2019 ASHS Annual Conference

Growers and wholesalers can store cut flowers of Paeonia lactiflora Pall. (peony) hybrids for 4 to 8 weeks to fill seasonal production gaps. However, vase life and quality of stored flowers is often less than flowers freshly cut or stored for <4 weeks. Due to peonies’ natural ability to withstand freezing temperatures prior to harvest, sub-zero temperatures may better preserve vase life and quality for longer durations than the industry standard of 0 to 1 °C. In year 1, cut stems of three peony cultivars: Festiva Maxima, Monsieur Jules Elie, and Sarah Bernhardt, were held at 3.5, 0.6, or -3.1 °C for 0 to 12 weeks. The industry standard, 0.6 °C, preserved vase life and other quality traits better than 3.5 and -3.1 °C. ‘Festiva Maxima’ was the least tolerant of storage with a vase life of 0, 4.1 and 1.0 days after 12 weeks at 3.5, 0.6, and -3.5 °C, respectively. ‘Monsieur Julies Elie’ was the most tolerant of storage at all temperatures. Specifically, at -3.5 °C, vase life was 5.3 and 3.2 d after 8 and 12 weeks, respectively. Sub-zero storage prevented weight loss similar to 0.6 °C. As storage duration increased the percentage of buds that fully opened decreased for all cultivars and temperatures, except ‘Monsieur Jules Elie’ held at 0.6 °C. Over 50% of ‘Sarah Bernhardt’ buds were unable to fully open after being held at -3.5 °C for 3 weeks. Across all temperatures, floral diameter of ‘Sarah Bernhardt’ decreased from 12 to 10 cm after 12 weeks of storage. During year 2, the sub-zero temperature was elevated to approximately -1 °C to alleviate loss of flower quality. Storage duration was extended to evaluate a storage period of 4 months, which would fill current gaps of peony production. Preliminary results show that sub-zero temperatures may be a viable alternative for storing cut peonies.