Fresh North Carolina strawberries in November?

by | Apr 14, 2009

If there is a fruit that seems to kick off spring, it’s strawberries. Appearing quickly and making a short, tantalizing run in production, strawberries herald the colorful and tasty buffet that is to follow — peaches, watermelon, tomatoes, etc.


Winter strawberries grown in North Carolina.

Luckily, research under way at the Piedmont Research Station in Salisbury may greatly extend the timetable for locally grown strawberries. The station has harvested strawberries for the past 26 weeks and has a goal of keeping plants in production for 40 weeks total. In comparison, an average strawberry plant typically produces six to seven weeks before warm temperatures halt production.

The station uses a passive solar system created by using high tunnels made of plastic sheeting and hoops. Joe Hampton, the station superintendent, describes the tunnels as a “poor man’s greenhouse” because they use no outside heating equipment or electricity. Instead, the outer layer of plastic covering the hoops captures daytime heat and raises the soil temperature, which protects the plants when night and temperatures fall.

The ends on the tunnel can be opened and closed to regulate the temperature and even allow tractors to come through if needed.

The technology is not new for commercial production. It has been used for around 20 years in Europe, but it is certainly uncommon for strawberries in North Carolina.  A few growers in the state, including Lewis Nursery and Farms in Rocky Point, have begun using the technology to produce an off-season crop.

There are six 100-foot tunnels at the Piedmont Research Station. Each tunnel houses around 800 strawberry plants. Hampton said researchers have found that Strawberry Festival, a berry variety produced in Florida that never produced well conventionally in North Carolina, responds well in the high tunnel environment. He expects a specific variety eventually will be developed for high-tunnel production in the state.

Part of the ongoing research is figuring out how to fertilize the plants to optimize yields over a longer growing cycle, determining economic feasibility of producing strawberries in tunnels and fine-tuning the production process to be able to handle cold snaps. So far researchers have found that the plants produce about three times the amount of berries compared to conventional methods, which could be a big boost to a farming operation.

While there is still more to learn, Hampton said the station has a regular stream of farmer visitors who are interested in the research and its potential for their farms.

With all the fresh strawberries being produced, you might think there would be strawberry desserts in the breakroom every Friday during harvest season, but the majority of the fruit is donated to a good cause.

The research station coordinates with the Society of St. Andrew, an organization that gleans fruit and vegetables to help feed the needy, to harvest the fruits.  About 1 percent of the berries harvested are analyzed for sugar content and other scientific characteristics to determine the overall taste of the berries, which is also a critical part of the research.

Historically, research has led to many new production practices on the farm that have both financial and environmental benefits. Most of the strawberries produced commercially today are grown on plastic, an advance that was pioneered through earlier research. Researchers found that growing strawberry plants on plastic produced twice as many berries, and farmers quickly adopted the practice. High tunnels may be the next big advance.