Charlie and the Pumpkin Patch

October 24, 2024
Two images show a ground level view of pumpkins attached to the vine. In the left, there is no clover and bare dirt around the vine. In the right, clover covers the ground.
Left: A pumpkin vine with little to no clover coverage. Right: A pumpkin vine with full clover coverage.

A few years ago, as SROC horticulture researcher Charlie Rohwer watched his pumpkins sprout and grow, he noticed a wide expanse of dark, bare dirt between the developing vines. This made him wonder: “What could you plant alongside pumpkins to grow two crops in the space of one?” To find out, Rohwer designed a study to investigate the interactions between various clover and pumpkin varieties.

In a pumpkin patch, a small red cart holds a scale which is being used to weigh white pumpkins. Charlie is putting a pumpkin on the scale while Jes records the weights on a clipboard.
Charlie switches out pumpkins on the scale while SROC Field Technican, Jes, records weights on the data sheet.

“You plant pumpkins in June, but it isn’t until late July that the leaves fill in and cover the ground. That gives almost 2 full months to establish a cover crop – like clover – that can help with weed suppression and add nutrients to the soil for the next year’s crop,” said Rohwer, standing knee-deep in scratchy pumpkin leaves.

Rohwer’s study first tested five different clover varieties to understand their resiliency to the regular herbicides used on pumpkin cash crops. This data allowed him to narrow down his study to the two most common pumpkin varieties and two carefully-selected clover varieties, which he planted in replicated plots at the SROC to establish whether interseeding clover and pumpkins impact the yield and size of the pumpkin crop. These varieties grow at different heights and rates, allowing Rohwer to measure which clover and pumpkin varieties work best together. Now in his third year of this research, his data suggests that clover has no significant impact when planted alongside pumpkins.

“Without much of an impact to the main cash crop, I can now look at what nutrient benefits the clover can add to the soil,” Rohwer said. “Since clover is hardier than pumpkins, after the first frost when the pumpkin leaves die back, it uses the extra sunlight in a final burst of growth that has the potential to increase the available nitrogen for next year’s crop.” The nitrogen-loving crop Rohwer plans to plant and test in this field next year? Sweet corn.

Rohwer believes this research will be beneficial to small hobby and family farms that grow a variety of cash crops at smaller scales. Based on this research, farmers could leave the clover as a winter cover crop to protect the soil from erosion and add nitrogen to rotational systems like pumpkins and sweet corn. With the numerous pumpkin patches and sweet corn stands seen across the state, this research could give those farmers a boost to their production and soil health while increasing their profitability.


Funding for this project is provided by the Minnesota Department of Agriculture through an Agricultural Growth, Research, and Innovation (AGRI) Sustainable Agriculture Demonstration Grant.