Author: Annie Klodd, Extension Educator - Fruit and Vegetable Production
Have you considered growing strawberries but don't want to commit to a perennial crop? Would you like to bring a high-demand, high value berry to the market in the late season?
You may consider trying some day neutral strawberries. "Day neutrals" are an annual crop that keeps producing fruit from late June to mid-fall, with peak production in August in Minnesota.
While the most common production system for day neutrals does require plastic, a biodegradable system was developed by UMN. More information is below.
Unlike June-bearing strawberries, day neutral types produce fruit as long as temperatures stay between 40-90 degrees F, with production tapering off toward the end of the season. In our climate, they must be removed at the end of the growing season just like annual vegetables.
Growers of day neutrals may expect between 0.5 to 1.0 pound of fruit per plant over the season. However, lower yields can occur, particularly for growers who are new to this crop.
Sweetness: Varieties vary in flavor and sweetness, and several northern varieties have been shown to have high sugar levels, which is a desirable market trait. In comparisons of day-neutral varieties, data collected at the UMN West Central Research and Outreach Center in Morris found that the day neutral varieties we grow in Minnesota were just as sweet or sweeter than June-bearing strawberries.
San Andreas and Albion were found to be the sweetest. Portola had the highest yields but was the least sweet of the six varieties tested. However, all varieties tested are relatively sweet. Albion offers a combination of high yield and good flavor and serves as a good option for beginners.
If each plant produces a good yield of 1 pound of fruit, 250 plants would produce 250 pounds of fruit under excellent growing conditions. Actual marketable yields may be lower considering pest pressure and rainy weather. Weather-related berry diseases are decreased by growing under low tunnels (more information below).
Yields vary by the time in the season. Yields typically peak some time in August, and decrease until October.
Since daily or every-other-day harvest of day neutrals requires considerable labor, it would be wise to trial this crop on a small scale to see how it works for your farm, before expanding.
Alternatives to plastic: UMN researchers have recently developed a system that uses biodegradable mulch instead of plastic, in order to address farmers' goals to reduce plastic use. Steve Poppe described that system in Fruit and Vegetable News in February 2019: https://blog-fruit-vegetable-ipm.extension.umn.edu/2019/02/developing-annual-day-neutral.html
Low tunnels: Low tunnels are not required, but some farmers grow day-neutrals under short, clear plastic low tunnels that are supported by steel hoops. This further extends the growing season, but perhaps the larger benefit is keeping out rainfall, which decreases disease. Yields in UMN research were not significantly different between open field and low tunnel systems, but there may be an increase in marketable yield under low tunnels.
Low tunnels may discourage deer, but will not exclude small mammals or insects like tarnished plant bug or spotted wing drosophila (SWD). A larger walk-under exclusion structure is needed to keep out SWD and tarnished plant bug (see photo).
Good drainage: Since strawberries grow on the ground, it is especially important to plant them in an area with good drainage that does not flood. Matted rows assist with water drainage in wet areas.
Row middles: Either landscape fabric or cover crops can be used between rows. There are pros and cons to both. Cover crops add valuable ecosystem services, but mowing cover crops between rows requires fossil fuels and adds labor costs. They also provide habitat for the devastating berry pest spotted wing drosophila (SWD). Landscape fabric adds a plastic input, but requires less maintenance during the season and minimizes SWD habitat.
I do not recommend leaving inter-rows bare with cultivation. This disturbs the soil structure and creates mucky conditions that are difficult to work in following rain.
Plant spacing: Plants should be spaced no closer than one foot apart on each side. A common setup is to plant two rows on each matted row, 12-18 inches apart. Planting too closely leads to smaller berries, soil nutrient stress, and lower yield per plant.
Removing flowers and runners: Stop removing flowers at the same time you would stop removing flowers on June-bearing strawberries. Blossoms should be removed from the plants for about the first four weeks after planting, or until some time in mid-June depending on the season. After that point, stop removing the flowers and allow the fruit to develop. Remove runners as needed. Runners are not needed for day neutrals, and they take energy away from fruit production.
http://fruit.umn.edu/content/new-day-neutral
https://experts.umn.edu/en/publications/yield-and-quality-characteristics-of-day-neutral-strawberry-in-th
Research cited in this article is based on:
Petran, A. et al. 2016. Yield and quality characteristics of day-neutral strawberry in the United States Upper Midwest using organic practices. Biological Agricultural and Horticulture 33(2).
 |
| Day neutral strawberries growing on matted rows with white-on-black plastic and landscape fabric. Photo: UMN/West Central Research and Outreach Center |
Have you considered growing strawberries but don't want to commit to a perennial crop? Would you like to bring a high-demand, high value berry to the market in the late season?
You may consider trying some day neutral strawberries. "Day neutrals" are an annual crop that keeps producing fruit from late June to mid-fall, with peak production in August in Minnesota.
While the most common production system for day neutrals does require plastic, a biodegradable system was developed by UMN. More information is below.
Unlike June-bearing strawberries, day neutral types produce fruit as long as temperatures stay between 40-90 degrees F, with production tapering off toward the end of the season. In our climate, they must be removed at the end of the growing season just like annual vegetables.
How do day-neutrals compare to June-bearing strawberries?
Yield: According to University of Minnesota research published in 2016 (citation below), day neutral strawberries typically yield significantly higher than June-bearing strawberries over the growing season. In this study, six day neutral varieties yielded consistently higher than common June-bearing strawberry cultivars and extended the harvest season by over 2 months.Growers of day neutrals may expect between 0.5 to 1.0 pound of fruit per plant over the season. However, lower yields can occur, particularly for growers who are new to this crop.
Sweetness: Varieties vary in flavor and sweetness, and several northern varieties have been shown to have high sugar levels, which is a desirable market trait. In comparisons of day-neutral varieties, data collected at the UMN West Central Research and Outreach Center in Morris found that the day neutral varieties we grow in Minnesota were just as sweet or sweeter than June-bearing strawberries.
Selecting Day Neutral Strawberry Varieties
Recommended varieties for Minnesota, which have been tested on multiple sites in multiple years, include: Albion, Evie-2 (Evie-II), Monterey, Portola, San Andreas, and Seascape.San Andreas and Albion were found to be the sweetest. Portola had the highest yields but was the least sweet of the six varieties tested. However, all varieties tested are relatively sweet. Albion offers a combination of high yield and good flavor and serves as a good option for beginners.
How Many Plants to Order
The number of plants to grow depends on your space available, labor capacity, and your target marketable yield.If each plant produces a good yield of 1 pound of fruit, 250 plants would produce 250 pounds of fruit under excellent growing conditions. Actual marketable yields may be lower considering pest pressure and rainy weather. Weather-related berry diseases are decreased by growing under low tunnels (more information below).
Yields vary by the time in the season. Yields typically peak some time in August, and decrease until October.
Since daily or every-other-day harvest of day neutrals requires considerable labor, it would be wise to trial this crop on a small scale to see how it works for your farm, before expanding.
 |
| Day neutral strawberries near the end of the season, in late September. Photo: Annie Klodd |
Caring for your day-neutral strawberries
Mulching: Grow day-neutral strawberries on biodegradeable mulch, white or black plastic, landscape fabric, or straw. The UMN research mentioned before found that growing day-neutral strawberries on matted (raised) rows with black plastic or white-on-black plastic achieved higher yields and larger berries than when planted on straw mulch. Growing the berries directly on soil is not recommended.Alternatives to plastic: UMN researchers have recently developed a system that uses biodegradable mulch instead of plastic, in order to address farmers' goals to reduce plastic use. Steve Poppe described that system in Fruit and Vegetable News in February 2019: https://blog-fruit-vegetable-ipm.extension.umn.edu/2019/02/developing-annual-day-neutral.html
 |
| Day-neutral strawberries growing on white plastic, in a trial at Cornell University. There were still ripe berries present in November, though the flavor had diminished. Photo: Annie Klodd |
Low tunnels: Low tunnels are not required, but some farmers grow day-neutrals under short, clear plastic low tunnels that are supported by steel hoops. This further extends the growing season, but perhaps the larger benefit is keeping out rainfall, which decreases disease. Yields in UMN research were not significantly different between open field and low tunnel systems, but there may be an increase in marketable yield under low tunnels.
Low tunnels may discourage deer, but will not exclude small mammals or insects like tarnished plant bug or spotted wing drosophila (SWD). A larger walk-under exclusion structure is needed to keep out SWD and tarnished plant bug (see photo).
 |
| Day neutral berries under an SWD exclusion structure at Twin Cities Berry Company. Photo: Annie Klodd |
Good drainage: Since strawberries grow on the ground, it is especially important to plant them in an area with good drainage that does not flood. Matted rows assist with water drainage in wet areas.
Row middles: Either landscape fabric or cover crops can be used between rows. There are pros and cons to both. Cover crops add valuable ecosystem services, but mowing cover crops between rows requires fossil fuels and adds labor costs. They also provide habitat for the devastating berry pest spotted wing drosophila (SWD). Landscape fabric adds a plastic input, but requires less maintenance during the season and minimizes SWD habitat.
I do not recommend leaving inter-rows bare with cultivation. This disturbs the soil structure and creates mucky conditions that are difficult to work in following rain.
 |
| This photo demonstrates recommended spacing for day neutral strawberries. These plants are being grown on matted rows on white-on-black plastic, under low tunnels. Photo: Annie Klodd |
Plant spacing: Plants should be spaced no closer than one foot apart on each side. A common setup is to plant two rows on each matted row, 12-18 inches apart. Planting too closely leads to smaller berries, soil nutrient stress, and lower yield per plant.
Removing flowers and runners: Stop removing flowers at the same time you would stop removing flowers on June-bearing strawberries. Blossoms should be removed from the plants for about the first four weeks after planting, or until some time in mid-June depending on the season. After that point, stop removing the flowers and allow the fruit to develop. Remove runners as needed. Runners are not needed for day neutrals, and they take energy away from fruit production.
For more information on growing day neutral strawberries, see:
https://blog-fruit-vegetable-ipm.extension.umn.edu/2019/02/developing-annual-day-neutral.htmlhttp://fruit.umn.edu/content/new-day-neutral
https://experts.umn.edu/en/publications/yield-and-quality-characteristics-of-day-neutral-strawberry-in-th
Research cited in this article is based on:
Petran, A. et al. 2016. Yield and quality characteristics of day-neutral strawberry in the United States Upper Midwest using organic practices. Biological Agricultural and Horticulture 33(2).
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