Midwesterners are accustomed to having local strawberries available for only a few weeks out of the year, from about mid-June to early July. That's because the majority of strawberries grown in the Midwest are June-bearing varieties, which are day-length sensitive. However, a relatively new type of strawberry, called day-neutral strawberry, is showing much promise for commercial production in the Midwest. Day-neutral strawberries are not sensitive to daylength and have consistent fruit production from early July until October, or whenever blossoms freeze. Production of day-neutral strawberries is significantly different than June-bearing strawberries and they are the focus of this article.
In the Midwest, the production of day-neutral strawberries differs from June-bearing strawberries in several important ways. First, day-neutral strawberries are typically grown as annuals, whereas June-bearing strawberries are grown as perennials. Second, day-neutral strawberries perform better and benefit from season extension when planted into plastic mulch and grown under protected culture, such as low or high tunnels. Third, runners are continually removed from day-neutral strawberry plants throughout the growing season to encourage greater fruit production. Because of these differences, day-neutral strawberries are more labor intensive to grow but have a longer harvest season and typically yield higher than June-bearing strawberries.
According to the University of Minnesota Extension, day-neutral strawberries should be planted in two rows per bed with 8-12 inches between rows and 18-24 inches between beds to allow for movement of equipment and pickers. Plants are spaced 8-12 inches apart within rows. Between beds, soil should be covered with cover crops or landscape fabric. Flowers should be removed for four to six weeks after planting to help with establishment. Plants require around 1-2 inches of water per week and drip irrigation is best. Day-neutral strawberries have higher nutrient demands than June-bearers due to their constant fruit production. Pre-planting soil applications of phosphorus and potassium followed by in-season fertigation of nitrogen is recommended. Harvest should occur every one to three days to reduce pest infestations and increase marketable yield.
Several different pests and diseases can affect day-neutral strawberries. Some of the more common pests in the Midwest are Japanese beetles, spotted wing drosophila (SWD), tarnished plant bug, aphids, thrips, and slugs. The use of low tunnels helps prevent a majority of pest damage, with other pest management options available for both conventional and organic growers. Some of the common diseases that impact day-neutral strawberry production are Botrytis gray mold, Phomopsis leaf blight, powdery mildew, leaf spot, and anthracnose.
For more information and resources on day-neutral strawberry production, visit University of Minnesota Extension.
RESEARCH STATUS AND PRIORITIES
Research into day-neutral strawberries has grown considerably in the last ten years in the Upper Midwest, spearheaded by the University of Minnesota. Past and current projects include biodegradable mulches; between-row cover crops and living mulches; low-tunnel vs. open-field production; the feasibility of table-top production in the Upper Midwest; and attracting pollinators by planting borage. Visit the University of Minnesota Extension website for more information.
Currently, researchers at the University of Wisconsin-Madison and University of Minnesota have a project funded by the USDA-NIFA organic transition program focusing on the use of plastic and biodegradable mulches to control insect pests, weeds, and diseases. The project is also exploring the economic aspects of growing organic day-neutral strawberries. Field updates and insect scouting reports from UW-Madison trials can be found on the Wisconsin Fruit Program website.
Day-neutral strawberries can be marketed in all the same ways as other strawberries. Their extended productivity from July until October means there is less competition from June-bearing strawberries. Day-neutral strawberries are as sweet, if not sweeter, than June-bearing strawberries, making them an excellent choice for the fresh market. Most strawberries are sold direct to consumers through markets such as U-pick, roadside stands, CSAs, pre-picked on farm sales, and farmers markets. A few mid-sized and wholesale markets are available as well as value added markets.
Day-neutral strawberry varieties that work well in the Upper Midwest include Albion, Seascape, Evie-2, Portola, San Andreas, and Cabrillo. University of Minnesota Extension has outlined key traits for each cultivar, which can help growers select the best varieties for their operation. Cornell University maintains a list of nurseries that sell day-neutral strawberries. Due to limited supply, plants should be ordered early (November/December) to ensure availability.
Dr. Suzanne Slack of Iowa State University and Matthew Gullickson of University of Minnesota, share information on how to grow day-neutral strawberries in the high tunnel environment.
Practical Farmers of Iowa hosts farmer Aaron Wills from Little Berry Farm near Northfield Minnesota to talk about using caterpillar tunnels to produce day-neutral strawberries from summer until fall.
Annie Klodd of University of Minnesota Extension and Courtney Tchida of the MN State Horticultural Society talk about growing day neutral strawberries organically.
Annie Klodd, Steve Poppe, and Kate Fessler of the University of Minnesota talk about different day-neutral strawberry production systems.
University of Minnesota Research Scientist Steve Poppe introduces the basic concepts of growing day-neutral strawberries under a low tunnel system.