Heirloom Watermelon Varieties

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For me, watermelons are one of the most amazing crops to grow. From skinny vines and small, pale yellow flowers there appears a fruit whose succulence and sweetness punctuates the summer experience. Throughout our country, we tend to have different experiences when it comes to watermelon growing and eating.

Watermelon loves heat and lots of it. In most of the cooler parts of the country, for example the Northeast, the large, oblong and weighty melons will not mature. The rounder shorter-season varieties of watermelon, sometimes dubbed icebox watermelons, will usually do well depending on the weather, latitude and elevation. A slightly cooler summer or a rise in elevation may not allow melons to fully ripen in some locations. In northern coastal or mountain areas, watermelon cultivation outside of a greenhouse may be impossible.

Heirloom watermelons of comparable size typically ripen later than hybrids. For growers in cooler climes, heirlooms are riskier. In the case of northern regions, there are a number of modern varieties that will mature a couple of weeks earlier, such as Golden Midget, Sugar Baby and Blacktail Mountain.

Watermelon, Citrullus lanatus, is a frost-sensitive annual vine with deeply indented, lobed and hairy leaves with climbing tendrils. It is a member of the squash family, and it has a superficial resemblance to squash plants. The vines produce unisexual flowers — that is, either male or female flowers as opposed to bisexual or perfect flowers like a lily or rose. Its fruit is a large berry called a pepo.

The genus Citrullus comprises four species, including watermelon and Citrullus colocynthis, a perennial known as bitter gourd or apple, which occurs as both a wild and domesticated plant. It was used as a purgative and antiparasitic — among other uses — since ancient times and is mentioned in the Bible.

Two other species of Citrullus are endemic to the Namib Desert of southwestern Africa, C. ecirrhosus and Citrullus rehmii.

All species of Citrullus are derived from wild C. lanatus, which originated in the subtropical regions of southern Africa particularly in the Kalahari Desert. Here, a small melon grows wild known as tsamma or tsama, believed to be the ancestor of our modern-day watermelon. These melons form a “group” of closely related variants, though they differ widely in taste and uses by indigenous people. Many are bitter and roasted over a fire before consumption, while others are somewhat sweet and eaten fresh. Some types appear to be more closely related to the citron melon, C. lanatus var. citroides, a small domesticated heirloom variety whose rind is used in pickling and preserving. The tsamma melon was used as a source of water for people crossing the desert, and the story goes that it was only possible to cross during tsamma season. The bitter C. ecirrhosus also is referred to as tsamma.