Protection for raspberries from the elements may be more of a necessity than a luxury for consistent and profitable production.
Protected agriculture is becoming a big deal in both the vegetable and fruit industries. There are quite a few large protected raspberry production farms in states like California. In the Northeast and Midwest, many raspberry growers have been growing raspberries in high tunnels, but on a smaller scale. Main contributing factors may have been advances in structures, plastic films, lights, fertilizers, and pest control materials. Other reasons could be adverse weather events that dashed growers’ plans for a profitable season.
Protected raspberry production is already a big business in California. I visited a high tunnel raspberry production farm in the state’s Central Valley as a part of the Annual Conference of North American Bramble Grower Association in 2018. Even though I had seen quite a few berry farms over the years, I was still amazed by how big and nice that high tunnel raspberry operation was. This farm was a contract production operation for Driscoll’s. There were acres and acres of raspberry production under gutter-connected high tunnels. High tunnels certainly helped the farm owners protect raspberry plants from diseases, extreme temperatures, nuisance wildlife, pests, rain, wind, and other risks. One of those neat innovations we saw there was a C & N Bug Vac. It was really interesting to see this machine in operation. Insects inside the raspberry high tunnels were quickly vacuumed into a trap in this machine. This Bug Vac is a highly effective and pesticide-free way to manage insects.
Season Extension Benefits
Raspberry production in high tunnels in the Midwest and Northeast has been a good way to increase yield, extend the harvest season, and improve fruit quality.“Tunnel yields were more than twice those of field-grown plants, and tunnel raspberries were 20% to 40% larger than those from the field. Fruit rot in tunnels has been greatly reduced from levels in the field,” Dr. Eric Hanson, professor of small fruits at Michigan State University, and his colleagues report. “Summer-fruiting raspberries have an annual net profit above allocated costs of $6,750 compared to $31,053 for fall-fruiting cultivars.”
I asked Dr. Hanson for advice to give growers who want to get into high tunnel raspberry production.“One big issue is knowing where to sell and at what price. I think in the Midwest, you need to achieve a higher price than the discount prices for California or Mexican berries in regional grocery stores, perhaps a goal should be $7 to $9/lb. That means $2.50 to $3.50 per half pint clamshell.
The second need is enough free time for daily management of the plants and tunnel. The investments are substantial, so a grower cannot neglect the system for a few days when other tasks require attention,” Hanson says. “Attention to detail is particularly important with the presence of SWD. Fruit need to be picked frequently and completely; no fruit can be missed and left to support fly reproduction. The last major need is a reliable labor pool for harvest. If you fall behind, SWD numbers ramp up and quality goes down.”
I also asked him what makes more sense: a three-season or a four-season high tunnel. Hanson said growers need to consider the scale of production in order to make the right decision.
“If a grower wanted to sell limited volumes, or start out as a trial with limited initial investment, a stand-alone tunnel may make sense. These are expensive per unit area covered, so prices received need to be high,” Hanson says. “I think potted plants may be well suited to stand-alone tunnels because yield per area is higher, and stand-alone tunnels can be used to alter the harvest season to a greater extent than three-season tunnels. The three-season, multiple-bay structures are much less per unit area, but a larger area needs to be covered so the initial investment is usually greater, as are the volumes to sell and labor needs.”
Is greenhouse raspberry production an economically viable option? Well, possibly. There have been published research papers and extension articles. Commercial adoption has not been as wide as high tunnels. With the advances in LED lights, greenhouse glasses and frames, fertilizers, substrate, and computer technology, profitable greenhouse raspberry production could become a reality for many. If you are running such an operation, I would love to hear from you.
Author’s note: To explore the feasibility of greenhouse raspberry production at Ohio State University, my visiting scholar, Ricardo Median from Brazil, is conducting a preliminary experiment on the use of LED lights in greenhouse raspberry production. He and I would like to thank Dr. Abhay Thosar of Signify for furnishing LED lights for us. We also thank Dr. Chieri Kubota, professor of Horticulture and Crop Science at The Ohio State University for her guidance.