Cucurbits are a large group of vegetable plants prized by home gardeners for their interesting and tasty fruit. The possibility of cross-pollination between cucurbit plants such as pumpkin and squash has led some home gardeners to believe that planting these crops together should be avoided. However, cross-pollination of curcurbits occurs only between members of the same species. Because pumpkin and squash are part of the same species, Cucurbita pepo, they can cross-pollinate, but this doesn't always affect fruit quality or yield.
Squash is a type of edible gourd and is divided into two types: summer and winter squash. Summer squash plants are typically large and bushy, while winter squash are largely vining plants, although some varieties are categorized as semibush. Both types of squash produce a wide range of fruit colors and shapes. For example, crookneck squash fruits are yellow, with tapered, curved necks, while zucchini fruits are club-shaped and green.
Pumpkins are categorized by fruit shape, fruit size and flavor, and may be vining or bushy. Like squash, pumpkins vary in color, with varieties that are typically shades of orange, red-orange, yellow or tan. Pumpkin size varies significantly among varieties. Dwarf pumpkins can weigh less than 5 pounds, while the standard pumpkin (Cucurbita pepo), produces fruit that weighs about 7 to 10 pounds. Cucurbita maxima varieties, on the other hand, produce large fruit that can weigh 50 to 100 pounds.
Growing Squash and Pumpkins Together
Cucurbit plants produce male and female flowers. The pollen is transferred from the male flowers to the female flowers on the same plant so that the fruit sets. While cross-pollination is possible among some cucurbits, it can occur only within the same species. Because pumpkin and squash are part of the same species, Cucurbita pepo, they may cross-pollinate if planted close to each other. However, the fruit quality of the current season’s harvest is not typically affected. If the seeds produced in that season’s fruit are planted, though, the fruit that sets the following season will be different than that of the parent plants. For example, planting the seeds of pumpkins growing next to a striped squash may result in a striped fruit that is similar to a pumpkin in shape and color.
All cucurbits require similar growing planting methods, but they vary in their growing season and time to harvest. Squash and pumpkin can make good companions because both require a long growing season with warm temperatures. Both crops grow best with temperatures that range between 65 and 75 degrees Fahrenheit. Summer squash requires 50 to 60 days from planting to first harvest, while pumpkins and winter squash require 90 to 120 days. Squash and pumpkin must be planted only after the soil has warmed to 60 degrees F, and both are typically planted in hills or mounds. This planting method ensures that water drains away from the seedlings, which prevents rot. Once seedlings emerge, pumpkins and squash should be thinned so that only two or three of the healthiest seedlings remain in each mound.
- The Old Farmer’s Almanac: Pumpkins
- Iowa State University Extension: Growing Squash in the Home Garden
- University of Wisconsin Extension: Growing Pumpkin and Other Vine Crops in Wisconsin
- Colorado State University Extension: Cucumber, Pumpkins, Squash and Melons
- University of Nebraska at Lincoln: Cucurbit Family and Cross Pollination
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