Longer-lasting cut flowers: the subzero solution

Cold storage of cut flowers is often a necessity. On most farms, it is impossible to harvest enough flowers to satisfy the immediate needs of all customers and markets. Storing cut flowers at cold temperatures of 35-39°F reduces respiration and transpiration, allowing them to remain fresh and have a longer vase life. The duration that flowers can be stored varies with the species, from a few days to several weeks. The majority, however, can only be stored for a few days to a week before vase life is reduced.

It would be greatly advantageous for flowers to be stored longer than a few days. If cut flower growers could hold cut flowers for an extended time, products could be stocked more easily for holidays, markets, and events. In addition, growers would be able to manage excessive production that can occur if warm temperatures speed up crop schedules.

Subzero storage (storage at temperatures of 31°F/-0.6°C) may be useful in extending storage length without sacrificing vase life. Earlier work at NC State showed that tulips could be held at 31°F for 9 weeks with no loss of vase life, and peonies had improved flower opening and quality after being held at 31°F for 16 weeks compared to 33°F.

The objective of our latest study was to develop a practical long-term storage process for selected cut flower species using subzero temperatures. In this article, we will be sharing the results of one experiment from our study. Click here to see the other experiments and results.

We evaluated differences in viability, vase life, and quality of 17 commercially important cut flower species: alstroemeria, anemone, campanula, carnation, chrysanthemum, delphinium, freesia, gerbera, gypsophila, larkspur, lily, lisianthus, ranunculus, rose, stock, sunflower, and tuberose when stored dry at either 31°F or 39°F for durations of 4, 8, and 12 weeks. Results showed that all species stored at 31°F were comparable to or had longer vase life than stems stored at 39°F. Tuberose stems were not viable after holding for any storage duration or temperature. When stored at a subzero temperature for extended periods, many species did not lose as much water and had less disease than when held at 39°F. However, the length of storage that freshly cut flowers can withstand without loss in viability or quality varies among species and cultivars. Rose and carnation stems were the most tolerant of extended storage durations, up to 12 weeks.

This study offers a valuable solution for flower producers. By storing blooms at subzero temperatures, they can ensure longer vase life and better match supply with market demand. Especially during times when unexpected weather conditions speed up flower production, this method offers a fallback to manage early harvests effectively.

In the future, more research will be needed to check if results are consistent across various flower cultivars. But for now, storing flowers dry immediately after harvest seems like a promising and cost-effective solution.

Source: endowment.org