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Pumpkin Patch Paradox

Complexities of Cultivation in a Shifting Climate

Different colored pumpkins spilling out of large baskets.
Courtesy of Canva.com

The autumn season, also known as fall, is meteorologically defined in the Northern Hemisphere as the three month period of September through November and represents a season of transition. Summer heat transitions to crisp, cool days; the colors of the leaves transition from green to different hues of yellow, orange, and red; the length of daylight shortens; and our wardrobe transitions from tank tops and shorts to sweaters and long pants. We also begin noticing pumpkins decorating many homes across the U.S. during this time of year.

Pumpkins are a staple of the autumn season and pumpkin-picking is a tradition enjoyed by many across the U.S. We decorate our homes with pumpkins and fall flowers such as Chrysanthemums, create jack-o-lanterns as Halloween approaches, and pumpkin food items (e.g., pies, lattes, coffee, soups, and many more) are abundant and can be found most anywhere we go.

Figure of a pie chart showing pumpkin production by states in 2021. Illinois has the greatest value, closely followed by Indiana, California, Texas, Michigan, and Virginia (in that order).
Fig 1. Pumpkin production by State for 2021. (Source: USDA Economic Research Service

Pumpkins are produced across all states. However, according to the U.S. Department of Agriculture (USDA), Illinois is the top pumpkin-producing state (Fig. 1), harvesting close to 30% of all the pumpkins produced across the U.S. While Illinois produces the most pumpkins, close to 80% of the pumpkins harvested there are processed and canned for products such as pumpkin puree, while the other states sell mostly fresh pumpkins that are used for decoration.

Weather impacts on pumpkin production

Like any other crop, deciding when to begin planting pumpkins can be tricky. In order to have pumpkins by autumn, farmers usually begin planting from late May to early July, depending on the location. And after planting, 120 days later, pumpkins are typically harvested.

Despite their hard exterior, pumpkins are very sensitive to weather conditions.

Frost/freeze: If farmers plant too early in the spring, when below-freezing temperatures can still occur, then there is a chance that the plant is susceptible to frost, and this could cause the plant to die. Frost or freeze episodes are usually less of a concern during autumn, when temperatures begin to drop, since the plants have reached maturity and the damage is much less.

Extreme heat: If it is too hot during summer, this could lead to wilted plants or potentially cause the pumpkin flowers to fall. In order for plants to produce crops, pollination needs to occur. However, during very warm days, the pumpkin flowers stay open for shorter periods of time, affecting the effectiveness of pollination.

Extreme wet conditions: If it rains too much and the soil is extremely wet, this could lead to a delay in planting during spring or harvesting during autumn. Very wet conditions can also lead to nutrient deficiencies, delayed maturity of the plant, and also increases the chance of the development of plant disease such as mildew.

All of these examples can lead to significantly fewer pumpkins than normal. However, extremely wet conditions have the biggest impact on pumpkin production, and are usually pumpkin farmers’ top weather-related concern. It has been reported that during the very wet years, especially during late summer and early fall, when pumpkins are reaching their maturity, pumpkin growers tend to see that the fruit quality decreases, there are fewer pumpkins, and more disease spreads across the plants.

Graph of the “Fresh pumpkin availability per capita” from 2000–23.
Fig. 2. Fresh pumpkin availability per capita for the period of 2000–2023. (Source: USDA Economic Research Service)

While the production of pumpkins can fluctuate from year to year due to weather, there was a visible reduction in pumpkin availability in 2015 (Fig. 2). This was mainly due to heavy rains that affected the Midwest region during the crucial time for pumpkin planting.

While the months of May and July were wetter-than-normal for Illinois, the month of June was extremely wet (Fig. 3). June 2015 is Illinois's wettest June on record with a total of 9.44 inches of rain—which is 5.35 inches more than normal. June 2015 is also Illinois’ second-wettest month for any month on record, trailing behind September of 1962 (9.62 inches).

Map of the “Statewide Precipitation Anomaly” in the contiguous U.S. in June 2015. The bottom shows these values—Precipitation: 3.55in; Anomaly: 0.63in; Rank: 9th Wettest; Mean: 2.92in.
Fig. 3. Map of the “Statewide Precipitation Anomalies” for June 2015. (Source: NCEI Climate at a Glance)

During the three-month period of May–July during 2015, Illinois averaged 20.04 inches of rain, which is 8.24 inches more than normal, and ranked as the wettest May–July period in the state’s 130-year record.

The very wet conditions during the planting season flooded fields and caused disease and mildew to spread. Eventually, when drier conditions returned, farmers replanted, but the damage was done and the yield of pumpkins was much lower. Overall, this led to slightly more than a 50% reduction in Illinois’s production of pumpkins (from 652 million pounds to close to 318 million pounds of pumpkins).

Map of the “Statewide Precipitation Anomaly” in the contiguous U.S. for the three-month period of May–July 2015. The bottom shows these values—Precipitation: 11.22in; Anomaly: 2.61in; Rank: Wettest; Mean: 8.61in.
Fig. 4. Map of statewide precipitation anomalies for the three-month period of May–July 2015. (Source: NCEI Climate at a Glance)

Climate change and pumpkin production

“Climate change is projected to reduce the availability and affordability of nutritious food, with impacts being unevenly distributed across society.” – Fifth National Climate Assessment

The Earth’s climate is warming and despite the overall global temperature increase seeming to be small, its effects can be significant at the local level.

The U.S. is not exempt from the effects of climate change. The contiguous U.S. annual average temperature has increased 0.16°F per decade since 1895; however, it is close to three times more (0.46°F) since 1981. Meanwhile, precipitation totals at the national-level have increased at 0.17 inch per decade since 1895 and no increase is evident since 1981.

Two graphs stacked. The top graph shows the “Contiguous U.S. Average Temperature” from 1895–2023 trend, while the bottom graph shows the “Contiguous U.S. Precipitation” from 1895–2023 trend.
Fig. 5. U.S. annual (a) temperature and (b) precipitation anomalies for the period of 1895–2023. (Source: NCEI Climate at a Glance)

A warmer climate will affect agricultural production, including pumpkins, across the U.S. through changes in the frequency and intensity of certain extreme events. The Midwest, which is known for its significant agricultural production, is already seeing the effects of climate change. The region has observed increased temperatures, longer growing seasons, and increased intensity and frequency of heavy rainfall events that lead to floods. The increasing warmer temperatures and the shifting of the growing seasons are also leading to larger pest populations that can harm crops and affect the production.

Extreme events are projected to continue to increase in intensity and frequency, putting agricultural production and availability at greater risk. 

Agricultural adaptation practices

While climate change is affecting many aspects of our lives, including our food security, farmers are preparing themselves for changes through agricultural adaptation. Agricultural adaptation is when farmers adjust their agricultural practices to reduce the effects of weather and climate change during crop production.

Across the Midwest, many pumpkin growers have implemented additional water resources (e.g. stock ponds, wells, among others) to help mitigate the effects of drought and protect their pumpkins and other crops. Some have implemented what is known as biological controls, which refers to using natural predators (e.g. spiders), parasites, or other living organisms that are found in the ecosystem to control certain pests from harming the crops.

While pumpkin farming, as well as other agricultural practices, are facing challenges as our climate continues to warm, farmers and scientists are continuously working together to better understand the impacts and how they can address those to continue successful farming and producing pumpkins (and other crops) for our nation.