Day neutral strawberries extend season
by Deborah Jeanne Sergeant
Strawberry growers’ season typically ends long before summer is over; however, selecting an everbearing variety – known as day neutral strawberries – can stretch the season until autumn. Practical Farmers of Iowa recently hosted a webinar presented by Aaron Wills, an organic farmer in Northfield, MN, who participated in a trial of day neutral strawberries using a few different management practices.
Wills’ operation, Little Hill Berry Farm, is in Zone 4B. He and his wife Molly founded it in 2011 with 1.5 acres of blueberries. The farm now boasts 4.5 acres of blueberries, five 150-foot caterpillar tunnels and one high tunnel of strawberries, a high tunnel of raspberries, a small field planting of raspberries and a half-acre of pumpkins, all certified organic. He also sells berry plants, garden starts, native plants and organic gardening supplies through an annual plant sale. Most of what he grows he sells as U-pick or pre-picked.
In 2018, Wills began experimenting with day neutral strawberries. Though his operation began with blueberries, “people love strawberries,” he said. Strawberries have overtaken blueberries on the farm.
June-bearing plants last three to four years in the field and produce from mid-June to early July. In their first year, farmers can expect no crop as the plants become established and send out runners to fill in the rows. “They only flower in a certain amount of daylight, which is why they only produce in spring,” Wills said.
Day neutral berries flower multiple times per season. Their fruit appears in early July and provides a continual harvest until the first hard frost. “In Minnesota, they are not winter hardy and they’re grown as annuals,” Wills said.
The University of Minnesota asked him to participate in a trial of growing day neutral strawberries. “I was interested in having strawberries for a different season,” he said. “The three-week season is here and gone. Offering customers strawberries for three months instead of three weeks, they’d sell themselves. People will buy them as fast as you can produce them.” He charges a premium rate for day neutral strawberries as they’re technically out of season later in the summer and in early autumn.
One of the growing methods he tried was with raised beds and low tunnels. The university provided use of automated equipment to create the beds and lay white plastic mulch on the rows for weed control. Wills said this system produced a higher yield than open field production. But he also experienced water pooling on top of the low tunnel plastic; issues with the wind blowing the plastic to the side; extra labor for raising and lowering the sides of the tunnels and installing and uninstalling them each season; and expenses. They can cost $800 for a 100-foot bed to cover two rows of berries. “It didn’t seem scalable, but it’s okay for two to four rows, not half an acre,” Wills said.
The other option was a raised bed in an open field, which was less labor intensive and could be scaled up. “We didn’t have the low tunnels to mess around with and we could plant a lot of plants in a big field pretty quickly,” he said.
But Wills said that in his second season with this system, a wet year contributed to leaf diseases. “As an organic grower, we didn’t have any answers for that problem,” he said.
He also experienced soft spots on the berries, since the plants were exposed to rainfall. He had to watch the weather forecast to harvest before the rain. Wills also had to mow between the rows, which was difficult.
Caterpillar tunnels represented another growing system Wills tried. Typical caterpillar tunnels are 14 feet wide by 50 or 100 feet long. “They function like a high tunnel with sides that go up, end walls if you want but they have less structural construction,” Wills said. Farmers using caterpillar tunnels cannot control the indoor temperature and environment to the degree they can in a high tunnel. Wills found that his caterpillar tunnels withstood summer storms and 70 mph winds without problems.
Strawberries are pollinated by bees. Since Wills’ tunnels are open on the ends and have retractable sides, he has not experienced problems with pollination.
“Ours can’t handle snow loads so we take the plastic off each fall,” Wills said. “It would be great to not have to do it. It’s not a great time suck, but I’d pay extra to get the Gothic style.” (That type was not available when he bought his.)
Still, he said that taking it down for the winter better exposes the soil to water and sunlight during the cold season. “Immediately by having the coverage of the tunnel, we had no leaf disease, no soft berries,” Wills said. “We were harvesting first quality berries.” Harvesting almost no “seconds” meant higher prices for his harvests.
He likes that he does not have to mow between the rows and he can harvest whenever he likes, irrespective of rain. But caterpillar tunnels have a high upfront cost. It is more difficult to offer U-pick.
“We try to plant them as early as possible,” Wills said. “The middle of April is ideal, but late April is alright. The sooner we get them in the ground, the sooner they get established. You do have to plant them by hand. I have not seen a way to plant them in a mechanical way.”
Wills pinches flowers that show up within the first two weeks after planting so the plants can become better established before producing fruit. He clips runners monthly through mid-August so the plants focus on fruit production. He harvests three times weekly and begins to see production build in July. The highest production is in August and early September.
Heat can overly stress day neutral strawberries. “When nighttime temperatures don’t go below 70º for a couple of days, they don’t produce flowers,” Wills said. Although that is not typically a problem for Wills, it does affect yield. Leaving the ends and sides of the tunnels up all summer helps with the heat.
Pests include tarnished plant bug. He sprays with PyGanic and vinegar as needed. So far, he has seen very little spotted wing drosophila pressure.
The varieties he’s found the best are Albion and Monterey. They both offer high yields, good flavor and good size. Albion produces higher yield later in the season while Monterey is more abundant earlier.
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