High-tunnel transplanting increases ginger yields

Durham, N.H. – For the relatively new crop known as “baby ginger,” delaying the harvest date increases yields in New Hampshire, according to preliminary research from the New Hampshire Agricultural Experiment Station at the University of New Hampshire.

The research was conducted by experiment station researcher Dr. Becky Sideman, professor of plant biology and extension professor and specialist in sustainable horticulture production, and Sabrina Beck, undergraduate research assistant, at the experiment station’s UNH Woodman Horticultural Research Farm.

“U.S. consumers are likely most familiar with the golden cured rhizomes of mature ginger plants, but recently, growers in the northeastern United States have been successfully producing ‘baby ginger,’ or rhizomes from young ginger plants grown for just a single growing season,” Sideman said. “Unlike mature ginger, the baby ginger is pink, tender, non-fibrous, and perishable. It can be used for cooking and can be candied or pickled, and keeps well in the freezer for culinary use year-round.”

Given the regional interest in growing baby ginger, experiment station researchers wanted to explore if early-season heating dramatically increases end-of-season yields, if growing in a low tunnel rather than a high tunnel could decreases costs, and if yields and/or quality of ginger is reduced by harvesting early, rather than late in the fall.

In New England, ginger seed rhizomes are typically purchased from Hawaii, and they arrive in late February or early March. Rhizomes are sprouted in trays held in temperatures ranging from 75 to 85 degrees Fahrenheit using a heat mat, germination chamber or other approach. They are transplanted into high-tunnel soils once the soil temperatures are consistently above 65 degrees Fahrenheit. Rhizomes are dug for market in fall, typically starting in late September, but prior to frost.

In this one-year study, they found ginger rhizomes sprouted much faster in flats that were on heat mats than in flats that were not kept on heat mats. In addition, the early-season heating also resulted in higher ginger yields once the ginger was transplanted in high and low tunnels. At each harvest date, the plots with plants exposed to early-season heating produced higher yields. With all dates combined, yields were significantly higher for the heated treatments.

“However, it is important to weigh this against the cost of heating. In our system, we ran a heat mat for nearly 12 weeks,” Sideman said. “We found that the first sprouts did not emerge until nearly 6 weeks after planting, even on the heat mat. Thus, the same results could likely be obtained by sprouting the ginger in a warm, insulated location without need for light for several weeks.”

When transplanted in high and low tunnels, the ginger in the high tunnels produced much higher yields than ginger grown in the low tunnels. According to Sideman, it is possible that low tunnels might be suitable for ginger production if other variables were modified, such as different coverings used and different fertility regimes. However, based on these preliminary results, the high-tunnel environment produced the best yields of high-quality ginger.

Finally, harvesting ginger early reduced yields. While it was possible to harvest nice ginger around September 1, yields were doubled by waiting an additional two months. “The take-home message here is that growers should delay harvest to maximize yields, and only harvest what is needed for earlier markets,” Sideman said. “It also may be worth considering charging a premium price for ‘early’ baby ginger, as it will result in less yield overall.”

This material is based upon work supported by the NH Agricultural Experiment Station, through joint funding of the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 1006928, and the state of New Hampshire. It also was supported by the NH Vegetable & Berry Growers’ Association. Additional information on this research is available from UNH Cooperative Extension in Effects of Early Season Heating, Low Tunnels and Harvest Time Ginger Yields in NH, 2017.