Pumpkin Size vs. Blueberry Size: The Reason for the Difference

A prize-winning gourd tipped the scales at 2,507 pounds (1,137 kilograms) during the All New England Giant Pumpkin Weigh-Off at the Topsfield Fair on Oct. 4, 2025.(Image credit: Photo by Erin Clark/The Boston Globe via Getty Images)

Every autumn, cultivators of pumpkins truck their outstandingly large produce onto scales; certain pumpkins tip the scales at more than 2,700 pounds (1,225 kilograms). In contrast, the planet’s bulkiest apple barely hits 4 pounds (1.8 kg), and the weightiest blueberry ever cultivated is under an ounce (28 grams). Therefore, what empowers pumpkins to attain such incredible dimensions while other fruits (indeed, pumpkins are fruits and additionally a variant of berry) stay relatively minute?

Monster pumpkins are a distinct cultivar of Cucurbita maxima that has undergone selective breeding to achieve enormous size — predominantly Mammoth and Atlantic Giant types. An underlying rationale for their capability to expand so noticeably lies in their status as indeterminate plants, Vikram Baliga, an assistant professor of horticultural practice at Texas Tech University, explained to Live Science. In contrast to determinate plants, which reach a defined stature and then cease growth, indeterminate plants prolong their growth endlessly.

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Determinate flora commonly yield their entire crop concurrently, presenting advantages for gathering but restricting their potential for dimensional expansion.

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“Certain flora, upon cultivating an organ — be it a leaf, a fruit, or a flower — possess a blueprint that restricts the ultimate dimensions of that particular item they generate,” Jessica Savage, an associate professor within the Swenson College of Science and Engineering at the University of Minnesota Duluth, informed Live Science. “Other species lack such limitations. … It appears that pumpkins, for some reason, don’t exhibit a potent constraint that governs their dimensions, thereby enabling us to selectively breed for amplified specimens.”

Lacking growth-limiting elements, pumpkin plants can constantly generate additional foliage to fuel energy production for their fruit.

“An indeterminate plant aims to create as much biomass as feasible, with utmost speed, thus your pumpkin will yield leaves, stems, and numerous other components,” Baliga commented. “Subsequently, when additional energy is required, it simply develops further leaves. It lacks that genetic deceleration point.”

How to grow a giant pumpkin

Growers exploit this characteristic by removing all pumpkins from the vine except for one.

“When you possess a plant capable of accumulating these resources, and you detach eight pumpkins, leaving only one, it effectively responds with, ‘Excellent, I’ll simply channel everything into this single fruit. It’s my exclusive opportunity to transmit my genes,'” Baliga clarified.

In theory, this strategy can be applied to other fruits as well. For instance, by eliminating all peaches from a tree except one, a larger peach can be cultivated. However, this is where the laws of physics come into play.

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For one thing, pumpkins mature on the earth’s surface, diminishing the effect of gravitational pull; a gigantic peach would be unable to attain pumpkin-like proportions because it would detach from the tree well before reaching that magnitude.

Moreover, a pumpkin’s robust epidermis enables it to swell more significantly than a soft-skinned fruit. “You couldn’t develop a seriously hefty fruit on a delicate base because it would succumb to its own mass and fracture,” Savage remarked.

A pumpkin of 1,101-pound (499 kilogram) won the contest in Alaska State Fair in Palmer, Alaska in 2010.

Nonetheless, excessively rigid rind impedes the pumpkin’s ability to attain monumental dimensions. “Pumpkin raisers endeavor to pinpoint that perfect equilibrium — they avoid excessive stiffness, which inhibits expansion. … A ruptured epidermis diminishes competitiveness. Consequently, the epidermis needs adequate pliability coupled with sufficient strength to sustain its heft.”

During their early stages, colossal pumpkins possess delicate, thin skin, facilitating accelerated growth. As they advance in maturity, the epidermis solidifies, according to Savage. To prolong this tender, rapid development phase, growers employ tarpaulins to shield pumpkins from solar exposure.

At peak expansion, gigantic pumpkins can amass 44 pounds (20 kg) per day — and this immense bulk must transit through the fruit’s vascular structure, which Savage defines as “superpowered.” Savage and her colleagues discovered that giant pumpkins, when set against other kinds, possess a larger quantity of phloem, the fraction of the vascular configuration accountable for sugar transport.

“I frequently liken it to an interstate,” she stated. “Equivalent quantities can be moved along a modest interstate, but its velocity will be capped. To expedite and escalate resource flow … an expanded network of roadways becomes indispensable.”

Certain pumpkins achieve such magnitude that individuals utilize them as boats. Here, Cindy Tobeck navigates in a 634-pound (288 kilogram) pumpkin during the Sixth Annual West Coast Giant Pumpkin Regatta in Tualatin, Oregon. She finished in second position.

Giant pumpkins also benefit from a prolonged growth span. “Pumpkins linger on the vine for months … it’s nearly a five-to-six-month venture, or 180 days in specific instances,” Baliga noted. “Conversely, apples, peaches, pears, and numerous blueberry varieties exhibit a significantly truncated timeframe from blossoming to cropping.”

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Nevertheless, a similarly salient determinant of giant pumpkin dimensions lies in human intervention. “They’ve endured extensive selective breeding specifically for size, differentiating them from various foodstuffs, where selection additionally prioritizes gustatory qualities,” Savage indicated.

Pumpkins embody autumn and hold pivotal significance in Halloween and Thanksgiving customs, thereby earning a more distinguished niche in our culture compared to other fruits possessing comparable growth potential, such as cucumbers.

Savage, for her part, envisions continued expansion in pumpkin dimensions. “Ultimate constraints likely exist, but I believe we’ll persist in discovering means of surpassing them,” she postulated.

Fruits and vegetables quiz: Do you know where pumpkins, blueberries and broccoli come from?TOPICSLife’s Little Mysteries

Ashley HamerSocial Links NavigationLive Science Contributor

Ashley Hamer contributes articles to Live Science spanning domains from aerospace and quantum mechanics to wellness and cognition. She curates the podcast Taboo Science and formerly presented Curiosity Daily for Discovery. She’s also contributed articles to the SciShow and It’s Okay to Be Smart YouTube channels. Holding a master’s credential in jazz saxophone from the University of North Texas, Ashley’s distinctive background endows her scientific prose with originality and a unique, external viewpoint.

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