Evaluation of Raspberries Grown in High Tunnels for a Northern Climate

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2004: $6,000.00
Projected End Date: 12/31/2004
Matching Non-Federal Funds: $6,000.00
Region: North Central
State: Minnesota
Project Coordinator:


  • Fruits: berries (other)


  • Education and Training: demonstration, farmer to farmer, networking
  • Farm Business Management: new enterprise development
  • Pest Management: mulching - plastic
  • Production Systems: general crop production



    Lois Hoffbauer of Duluth recently received a grant to experiment with using a greenhouse-like high tunnel to provide Duluth customers a longer raspberry season. Her research could also create a new tool for sustainable agriculture in Minnesota and in other cold climates throughout the country.

    Raspberries are a high-value product in Duluth, where the Zone 3 short growing season makes visitors to the farmer’s market hungry for every bit of summer sweetness they can find. Talking about her experience with farming, Hoffbauer explained, “We learned years ago that, living this close to Lake Superior, we had to ‘cheat’ the weather any way that we could.” The high tunnel would extend the season on both ends, allowing her to produce raspberries earlier in the year and to experiment with fall-bearing raspberries.

    While tunnels like these have been used for annual crops, this is the first time they will be used for a perennial plant in Minnesota. Hoffbauer heard about Penn State’s experimental use of perennials under tunnels and wants to see how it will work in Minnesota: “I don’t know of anyone except Penn State that has had perennial crops under plastic. It will change the entire way that the plants live because the sun will heat up the ground even in the winter, then freeze again when the sun goes down.” Hoffbauer will compare high tunnel yields to yields of raspberries not under the tunnel.

    The new greenhouse will be up by the end of October. In the summer, field days will provide visitors a close-up look of the tunnels.

    Hoffbauer has been farming in Duluth for over 25 years. She and her husband have 12 acres of sustainably produced vegetables, fruits, and free-range chickens, and 50 acres of Christmas trees.


    Project Background

    Our farm consists of 12 acres if sustainably grown vegetables and fruits, free range chickens and 20 acres of Christmas trees. We use sustainable methods and Integrated Pest Management to work our farm. We use black plastic mulch for our tomatoes, peppers and pumpkins. Between the rows of tomatoes and peppers, we mulch with weed-free straw. We cover the tomatoes/peppers with a floating row cover got early season frost protection. On our corn crop we plant 10 varieties with various lengths of ripening. We use a 300 foot piece of floating row cover that goes over 12 rows at a time and as the corn grows, we move the cover up the field over successive rows. We have had tomatoes under high tunnel production for over 15 years. We already have our peers interested in out methods and adding another high tunnel would just add one more dimension.

    Project objectives:

    To provide fresh raspberries to customers in an extended fall season and enhance farm income, the project will evaluate the feasibility of utilizing a 96' x 30' hoophouse.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.