Project Pawpaw Orchard Network:
Wisconsin
The Project Pawpaw Wisconsin Research & Breeding Orchard was planted in May, 2025 in Spring Green, Wisconsin (USDA Zone 5a). The orchard contains 1,000 trees, 750 of which are a population being evaluated for cold tolerance and 250 which are planted in a replicated trial to identify best practices for pawpaw establishment in cold climates.
Similarly to the NJ orchard, this planting features woven ground cover to reduce weed management needs and buried drip irrigation. Tree tubes were installed to help provide protection from high winds and sun damage during establishment and to hopefully reduce freeze damage during the cold Wisconsin winters. More information about the orchard design and planting here.
This rapidly expanding network of research orchards is a testament to the power of crowdfunded research and plant breeding. The materials for these orchards were paid for solely through sales in-person at pawpaw festivals and through our online store, with time donated by researchers, farmers, scientists and volunteers. Supporting Project Pawpaw is one of the most straightforward and efficient ways to support pawpaw breeding efforts!
The orchard was planted by Project Pawpaw on land that is leased from the Savanna Institute, a nonprofit dedicated to catalyzing widespread agroforestry in the upper Midwest. Without the opportunity to lease this land, this planting would not have been possible!
Planting Details
The pawpaw orchard in Spring Green, WI is situated on an extremely flat site in the Wisconsin River Valley. The site was selected for its consistent silt-loam soil and challenging climate. The Wisconsin Research Orchard represents the coldest climate where formal pawpaw research is being performed, located just miles from Lone Rock, WI which recorded -53°F on January 30, 1951, and held Wisconsin's state record for coldest temperature for 45 years. This extreme climate makes the orchard an invaluable testing ground for cold hardiness research and for identifying genetics that can extend pawpaw cultivation into northern regions. By evaluating which selections can thrive in this challenging environment, Project Pawpaw can provide growers throughout the Upper Midwest with cultivar recommendations backed by real-world performance data under harsh winter conditions.
The site of the orchard has been in conventional row crop production for over 75 years. Field preparation included tilling planting rows into an established low-mow cover crop mix of annual ryegrass (as nurse crop), Chewings fescue, creeping red fescue, hard fescue, white clover, and narrow-leaved plantain, which remained in the alleys between rows. Fertility amendments of 44 lb N, 9 lb P, and 52 lb K per acre were incorporated before laying black woven ground cover onto raised beds using a plastic mulch layer, with Rivulis orchard tubing beneath the fabric. The field was laid out using high accuracy RTK GPS to ensure that the rows were straight.
While planting into a field with an established cover crop in the alleys reduced initial weed pressure between rows, creating raised beds from only the tilled soil presented challenges. Divots formed at the sides of the plastic mulch that were difficult to keep mowed, and weed seed fell into these troughs. An aggressive stand of jointgrass and other tall grasses took hold in these areas, presenting a significant management challenge throughout the growing season.
The 750 tree breeding section of the orchard is approximately 1 acre and is planted into rows on 12 foot centers with 5 foot in-row spacing, which is a higher density than would be recommended for commercial production. This decision was made to provide the population size required to develop tools for pawpaw breeding and give the best chance of finding superior seedlings that are able to survive the harsh Wisconsin winters. As trees die in the orchard, new seedlings will be planted in their place. Trees that are able to survive and thrive in this environment will be grafted into replicated trials and their fruit quality and other growing characteristics more closely examined. These trees were protected with 30" Tree Pro tree tubes secured on fiberglass tomato stakes.
The seedlings in the breeding section of the orchard were grown from seed collected from the late Jerry Lehman's orchard in Terre Haute Indiana. Jerry was a prolific collector and breeder of pawpaws and his orchard has a highly diverse population of trees, and the varieties selected out of Jerry's orchard routinely win competitions for size and flavor. Seedlings from this orchard have a high level of genetic diversity combined with parents that consistently produce excellent fruit quality, which increases our odds of finding selections that can not only survive in this stressful cold climate environment but also produce great quality fruit.
The 250 trees in the pawpaw establishment trial are planted in rows spaced 12 feet apart with 10-foot in-row spacing. This experiment is designed as a randomized complete block design (RCBD) with three blocks to test the effects of different tree protection methods on pawpaw establishment in the Upper Midwest's challenging climate.
The trial compares five treatments with 50 trees each: paperboard tree protectors, Tree Pro 30-inch tubes, Tree Pro 48-inch tubes, Tree Pro 60-inch tubes, and no tree protection. Tree tubes and shelters are commonly used to protect young trees from herbivory, wind damage, and harsh weather conditions while creating a microclimate that can promote early growth. However, their effectiveness for pawpaws in cold climates has not been systematically tested. This trial will evaluate which protection method, if any, provides the best establishment rates, early growth, and overall tree health in Spring Green's extreme climate. The results will provide growers throughout the Upper Midwest with evidence-based recommendations for establishing pawpaw orchards in challenging environments.
Funding for this orchard was raised entirely through the sale of pawpaw seedlings, shirts, grafting knives, and other merchandise at festivals and farmer’s markets and through the Project Pawpaw online store. The next research orchard is planned to be planted in Eastern Georgia, with future locations and collaborators in the lower midwest, west, and mid-atlantic regions being sought.
With Special Thanks To...
Andrey Vega Alfaro
Austin Cliffe
Chris D'Angelo
Leigha D'Angelo
Erik Hagan
Dave Hopey
Jordy Jordahl
Trygve Jordahl
Jacob Morse
Peter Morse
Audrey Morrison
Peter Morrison
Kathleen Rhoades
Heron Rose
Sue Stephens
Suzy Strickler & Joe
Owen Tanner-Flomberg
Sarah Tanner-Flomberg
Taylor Wartell
EXPANDING THE NETWORK
With our second Research & Breeding Orchard now established in Wisconsin, we're building momentum. But there's more work to do. Each new site adds crucial data on how pawpaw genetics perform across different climates, but new levels of complexity and expense to keep things running smoothly. Purchases from our online store directly fund additional orchard sites planned for the coming years. Your support helps answer the questions that will shape the future of pawpaw cultivation!