Science Friday

Everything You Never Knew About Squash And Pumpkins

November 26, 2025

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  • The difference between summer and winter squash is determined by the maturity stage at which they are eaten: summer squash is eaten immature, while winter squash is eaten when the fruit and seed are fully developed. 
  • Canned pumpkin is typically made from Hubbard squash or butternut-type squash, not the common jack-o'-lantern pumpkin, which is considered the lowest quality for eating. 
  • To ensure pure seed saving for squash and pumpkins, growers must manually control pollination by closing flowers before they open and using a male flower to pollinate the female flower to prevent unwanted cross-pollination by bees. 

Segments

Giant Pumpkin Growth Secrets
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(00:01:34)
  • Key Takeaway: Growing world-record pumpkins requires both superior genetic potential (like Dill’s Atlantic Giant seeds) and optimal growing conditions.
  • Summary: Giant pumpkins achieving nearly 3,000 pounds rely on ’nature and nurture,’ meaning the right seeds with high genetic potential combined with perfect growing conditions. The variety used for most giant pumpkins is Dill’s Atlantic Giant, developed in the 1970s, though top growers often use community-exchanged, selectively bred seeds. While one can buy Dill’s Atlantic Giant seeds, they may not yield the best results compared to specialized seeds.
Cucurbit Family Identification
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(00:03:19)
  • Key Takeaway: The Cucurbitaceae family includes squash, pumpkins, melons, cucumbers, and watermelons, and the distinction between squash types is based on harvest timing.
  • Summary: Squash and pumpkins belong to the Cucurbitaceae family, which also encompasses melons, cucumbers, and watermelons. Summer squash is eaten before maturity, often just six to eight days after pollination, whereas winter squash is consumed when fully mature, which can take around 60 days.
Gourd Versus Squash Definition
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(00:04:27)
  • Key Takeaway: In common usage, a squash is defined as an edible fruit, while a gourd is typically a hard-shelled, ornamental type of squash.
  • Summary: The difference between a gourd and a squash is contentious among scholars, but a working definition separates them by use. Gourds are often considered the more undomesticated type, with archaeological evidence dating them back to 13,000 BCE. Domestication of these fruits began around 10,000 years ago.
Canned Pumpkin Composition
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(00:05:46)
  • Key Takeaway: Canned pumpkin puree is usually made from Hubbard or butternut-type squash, not the common jack-o’-lantern pumpkin.
  • Summary: The fruit used for canned pumpkin is typically a Hubbard squash or a variety similar to butternut squash, as the standard jack-o’-lantern pumpkin is of lower quality for eating. In many other countries, eating a squash is commonly referred to as eating a pumpkin.
Pumpkin Breeding Priorities
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(00:06:30)
  • Key Takeaway: For pick-your-own pumpkin operations, the handle (peduncle) strength and attachment quality are the most critical traits breeders focus on.
  • Summary: Pumpkin sellers prioritize the handle because customers will not buy a pumpkin without one, and it must remain attached when picked up. Other important traits include desirable colors, sizes, disease resistance, and high yield potential for the grower. Current trends in decorative pumpkins include developing white varieties and breeding round or stacker types from the Cucuritum maxima species.
Myth of Milk-Fed Pumpkins
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(00:09:39)
  • Key Takeaway: The practice of feeding pumpkins milk via a string inserted into the vine, as described in Farmer Boy, does not scientifically aid in fruit development or size increase.
  • Summary: Giant pumpkin growers have tested the milk-feeding method, but it has not shown any benefit to the fruit’s development. The theory suggests the calcium in milk might help, but this effect has not been observed in practice. This method appears to be an invention of the author of the book.
Challenges in Squash Breeding
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(00:10:02)
  • Key Takeaway: The primary challenges in breeding new squash varieties are the large space requirements for testing populations and the long development timeline of six to eight years, making future market prediction difficult.
  • Summary: Squash and pumpkins take up significant space, which limits the size of breeding populations researchers can evaluate. It takes approximately six to eight years to develop a new variety, requiring breeders to predict consumer popularity far in advance. For acorn squash breeding, traits optimized include grower needs like disease resistance and earlier harvest, alongside quality metrics like dry matter (starch proxy) and sugar content (bricks).
Ensuring Pure Seed Lines
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(00:11:27)
  • Key Takeaway: Cross-pollination between different squash/gourd species is common via bees, necessitating manual pollination techniques to save pure seeds.
  • Summary: Zucchini, spaghetti squash, and gourds can cross-pollinate within the same species, and even across species to some extent. To guarantee seed purity, growers must exclude bees by closing flowers the day before they open with a twist tie. The male flower is then removed, used like a paintbrush on the female flower, and the female flower is immediately closed again.