Watermelon is always a harbinger of summer fun.

How to Tell the Difference Between Watermelon & Cucumber Plants

by Sarah Moore

Summer vegetable gardens are one of the best ways to bring kids outdoors during the sunny months. They love every part of the growing process, from planting to harvesting, and will especially enjoy eating the fruits of their labors. Because cucumber (Cucumis sativus) and watermelon (Citrullus lanatus) are so similar, refresh yourself on the differences in their appearance and growth habits and you’ll have an easier time helping kids tell them apart.


Cucumbers and melons belong to the same family of vine vegetables, Cucurbitaceae. They are both warm-weather plants, germinating outdoors once soil temperatures rise to at least 60 degrees Fahrenheit -- though watermelons may do better at 70 degrees. As annuals, both plants grow, flower, fruit and die within a single season, and produce fleshy fruits with outer skins and a large collection of inner seeds. Both will also grow in every part of the United States during the summer season, though you may need to adjust planting and harvesting times based on your region.


Both cucumbers and watermelons do well in hills, which encourage drainage and keep their roots cool, but generally cucumbers can tolerate growing closer together than can sprawling watermelons. While watermelon vines can grow to 10 feet and require spacing of eight feet between rows and hills, cucumbers only need to be spaced four to six feet apart. Both plants can grow three to a hill. An easy way to utilize the small garden spaces that many young families have is trellising. Both cucumbers and watermelons grow well on trellises, although watermelons will need support for their fruit, such as nylon tied in a sling underneath.


Cucumbers and watermelons look very similar, with twining vines, large leaves and small, curling tendrils near the tops of the fruit. The trailing stems of both are hairy. Both have large leaves. Watermelon leaves, however, are rounded and deeply lobed, with three main lobes that have their own individual indentations. Cucumber leaves, on the other hand, are triangular, without lobes.


Cucumbers and watermelons both come in different varieties, but generally cucumbers are much smaller than watermelons. They also have small spines on the outside, and can be elongated or round. Watermelons, on the other hand, are smooth and always round or slightly oval. Maturity time also differs for cucumbers and watermelons. While cucumbers will produce their first fruits between 50 and 60 days after germination, watermelons usually require 80 to 95 days and significantly hotter weather in order to develop the sugars that make its fruit sweet.

About the Author

Sarah Moore has been a writer, editor and blogger since 2006. She holds a master's degree in journalism.

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