High tunnels enhance cut flower production

AFP Correspondent

Dr. Chris Wien of Cornell University has compared field and high tunnel production with numerous species of cut flowers for over five years. He presented the highlights of his findings at the International Science for Horticultural Science Symposium on High Tunnel Horticultural Crop Production held in State College, Pa., in October.
Noting the increased use of high tunnels, Wien said, “They have become common structures on cut flower farms, as growers recognize that many cut flower species will produce earlier, higher quality blooms and longer stems in the protected environment than in an open field.”
In the Northeast, production is typically seasonal and marketed locally. Although many species are grown, roses, carnations and mums are usually not part of the product offerings. Producers gain a market advantage by emphasizing high quality and freshness.
While limited in volume, markets include farmers markets, roadside stands and events such as weddings. Some retailers such as Wegmans and Whole Foods Market feature local cut flowers.
High tunnels, Wien said, are ideally suited for high value and high density production. The season can be extended three weeks at each end. The tunnels shield rain from spotting flowers, and the ability to control water can reduce diseases. Also, tunnels protect against wind, resulting in taller flowers. Insects can be better controlled by their natural enemies. Wien added, “Organic production is not that tricky.”
However, disadvantages include the expense of a high tunnel. Plus, production requires intensive management, and excessive wind and snow can be a hazard to the tunnel itself.
In determining which flowers to grow, Wien advised growing high value species and those which have a long harvest season, receive a premium price if marketed early, and display higher quality when high tunnel-grown.
For example, sunflowers, although three weeks earlier than in the field, likely will give a net return per foot of high tunnel space of only 14 cents compared with the return on lisianthus of $2.08.
Lisianthus, in Wien’s research, shows marked advantages in high tunnels over field production. In his five years of trials, which averaged nine cultivars per trial, flower harvest begins 13 days earlier in the tunnel, stem length increases 11 percent, and yields rise 37 percent.
Wien has observed similar improvements in growth in many other species. Trachelium has shown 20 percent increase in stem length, while campanula has exhibited 31 percent longer stems.
Taking steps to manage ventilation helps control the higher humidity levels typical in high tunnels, which accelerate certain disease development. Some species, such as dahlia and zinnia, can require fungicides due to powdery mildew susceptibility.
Insect management, too, demands vigilance for pests that often plague greenhouse growers.
The longer growing season afforded by high tunnels permits succession cropping. Wien said early, cold-tolerant species such as larkspur and stock can be followed by heat-tolerant species including zinnia, snapdragon or calendula. Consequently, a high tunnel can be producing cut flowers from May through October.
The milder climate in a high tunnel in winter can ensure a two-week earlier harvest of tulips, a competitive advantage for early spring sales. In addition, high tunnel tulips show superior stem strength.
In conclusion, Wien reported that cut flower high tunnel production is ideal for organic production. In all production methods, high tunnel cut flowers result in greater yields and demonstrate better quality and earlier flowering. In addition, succession cropping can enhance profitability.