One of America’s most loved summer “fruits”, the watermelon, is actually considered a vegetable!
It is botanically a fruit, but the USDA categorizes it as a vegetable. According to the USDA, a vegetable is defined as “herbaceous plants of which some portion is eaten raw or cooked during the main part of a meal”.
The sweet, juicy treats are a favorite at picnics and outdoor events, such as July 4th celebrations. They are so popular that in 2007, Congress designated July as National Watermelon Month.
Have you ever wondered where that mouthwatering, tasty treat comes from, or how it was grown, or when it’s ready to pick? This article traces the journey of the watermelon through the centuries from its origins as a weed to commercial cultivation and beyond, to its final destination, your table.
Watermelons in Africa grow like weeds but are important water sources.
Kim-stock.adobe.com
From Wild African Vines to Cultivation
Watermelon Origins in the Sahara
The journey begins in Africa, where wild types still grow like weeds today. Like modern-day watermelons, these melons are full of water, and some have a similar colored green rind, but that is where the resemblance ends.
Instead of red flesh, they have pale yellow, almost white to light green flesh that tastes bitter and is much smaller in size. Some even have fuzz-covered rinds.
Debates have been ongoing for decades regarding which one of the native African wildtypes is the actual ancestor of modern-day watermelons, and which African region is the exact gene center. The one point that everyone does agree on is that the original melons were used and eventually cultivated as important water sources.
Ancient Egyptian Sweet Melons
The first record of watermelons being cultivated was between 3,500 and 4,000 years ago in Egypt. Watermelon seeds and leaves, as well as paintings, have been found in many Egyptian tombs, including King Tut’s.
A DNA sample taken from one of those leaves indicates the melon had sweet flesh and contained lycopene, which is responsible for the red color. Based on this exciting discovery and other research, scientists have concluded that ancient Egyptians had developed watermelons similar to modern-day melons.
How Watermelons Conquered the World
Spread Across Asia & Europe
Over the years, watermelons spread along the Mediterranean and other trade routes, eventually appearing in India and China during the 7th and 10th centuries, respectively. It is speculated that the spread was aided by travelers using them as a water source for long-distance travel. Greek and Roman physicians utilized them for medicinal properties. During the 13th century, the Moors introduced watermelons to the Iberian Peninsula. From there, they spread into southern Europe.
Arrival in the Americas
The earliest report of watermelons being grown in the United States was in Florida in 1576.
Breeding Breakthroughs: Charleston Gray to Seedless
Fast forward to 1938, when Charles Fredrick Andrus, a researcher at the USDA. ARS, US Vegetable Laboratory in Charleston, started breeding watermelons for increased sweetness and disease resistance. He released the classic Charleston Grey watermelon in 1954.
Since then, researchers continue developing new, improved varieties, selecting specific traits such as flavor, flesh colors, rind thickness, color and patterns.
Watermelon Flesh Colors & Carotenoids Explained
Carotenoid Pigments and Color Variations
Watermelon flesh color ranges in various shades of yellow, orange, pink and red. The variation is controlled by polygenes that regulate the synthesis of different carotenoids. Each carotenoid is a specific color pigment.
Yellow and Orange-Fleshed Watermelons
Yellow and orange-fleshed watermelons fall into a specialty market, as many people find them a novelty.
Seedless Watermelon Market Adoption
The first seedless watermelon was developed in Japan in 1939. However, in the beginning, no countries were interested in growing them. In 1985, seedless watermelons finally gained a 1% foothold in the American Fresh Watermelon Market through the persistence of one man, Ori Eigsti, who touted they were sweeter and crispier than seeded watermelons. It wasn’t until the late 1990s that seedless watermelons became popular due to their small size, lighter weight, and ease of eating without the hassle of seeds. By 2012, 92% of the US watermelon market consisted of seedless watermelons.
Modern Production in South Carolina
In 2021, the US was ranked as the 8th largest producer of watermelons worldwide, and SC the 8th highest producer within the US. In 2023, SC Grower reported Bamberg County as the top watermelon producer in the state. The county grew 1,297 acres, slightly more than half the total watermelon acreage reported for SC. (SC Grower report 2023).
A local watermelon field.
Anna Sarah Hill, ©2025, Clemson Extension
The watermelon journey does not end there. The second phase of the journey will take us through the complexities of production to the melon’s final destination—your table. Over the years, watermelon production practices have changed substantially. Changes were driven by the market shift from seeded to seedless watermelons, the necessity to combat the ever-changing pest pressures and the effort to make farming more efficient and sustainable.
How Watermelons Are Transplanted Using Plasticulture
Starting Seeds in Greenhouses
Traditionally, seeds were sown directly into the field. Nowadays, most watermelon seeds are started in the greenhouse, and plants are transplanted to the field.
Benefits of Plastic Mulch
Watermelons are grown in raised beds covered with black plastic. The plastic keeps the soil warm early in the season, allowing the plants to establish more quickly. After the vines grow out, the large leaves cover the plastic and provide enough shade to protect the fruit set and prevent the dark plastic from baking the roots during the hottest part of the growing season.
Drip Irrigation and Fertigation
Watermelon plants require large quantities of water and fertilizer. Drip tape is run down the side of the bed underneath the plastic. Drip irrigation puts the water directly in the root zone, where the roots can readily utilize it.
Reducing Evaporation and Disease Spread
Other benefits of drip irrigation are the reduction of evaporation and the reduction of the spread of foliar diseases. Growers can fertigate and apply some pesticides through the drip system.
Pollination & Pollinizer Rows
Why Seedless Watermelons Need Pollinizers
Seedless watermelons are sterile. A female flower only produces a melon if it is pollinated by a male flower from a seeded watermelon. Therefore, both types must be planted in a field.
Pollenizer Row Placement
Generally, the pollenizers are planted every 3rd row or every 3rd plant to ensure good cross-pollination.
Role of Bees in Pollination
The blooms are dependent on bees and other pollinators to spread the pollen. They open at sunrise and close at sunset, leaving a short time frame for the bees to do their work.
Pollination Failure and Fruit Loss
Female flowers require between 500 and 1,000 grains of pollen for proper pollination, requiring multiple visits by the bees. If melons are not properly pollinated, they will abscise before reaching maturity.
Pest & Disease Management
Fusarium Wilt in South Carolina
Diseases are the main problems that affect watermelons in the southeast. Many diseases are weather dependent, and disease pressure is variable between years.
The primary killer of watermelon vines in South Carolina is Fusarium Wilt, a soil-borne pathogen that attacks the plant’s vascular system.
Disease-Resistant Rootstock
Select seedless watermelon varieties have been grafted onto Fusarium-resistant rootstock material, such as hybrid squash. The rootstock confers resistance to the scion, protecting it from the pathogen.
Carolina Strongback Rootstock
A popular rootstock currently used by growers is ‘Carolina Strongback’, which is resistant to both Fusarium and Root-Knot Nematode. Scientists from the USDA, ARS, and Clemson University developed ‘Carolina Strong Back’ from two wild-type watermelons through traditional breeding techniques.
Insect Pressure and Rind-Worm Complex
Insect pests can also create problems during the growing season.
Some feed on leaves, vines or fruit, causing direct damage, and others cause indirect damage by transmitting viruses. Several insect species collectively called the rind-worm complex feed on the melon rinds and cause blemishes, making the fruit unmarketable.
Scouting and Preventative Treatment
Growers must stay vigilant and scout for disease and insect issues throughout the growing season. Issues need to be treated early before they become widespread problems. As soon as vines start growing off the plastic, growers should begin spraying to protect them from disease and insects.
Cover Sprays and Resistance Management
Rotating different chemistries and modes of action and applying recommended rates reduces the development of pesticide resistance. These treatments, called cover sprays, must continue through the end of harvest.
Harvest, Ripeness & Brix Testing
Signs of Watermelon Ripeness
A telltale sign that fruit is ready for harvest is that the vine closest to the watermelon turns brown or starts to crack. The curly tendril connecting the melon to the vine will also turn brown and wither.
Unlike fruit that can be picked slightly unripe and then left to ripen on the counter, watermelons immediately stop ripening as soon as they are separated from the vine. This means it is important to ensure that the melon is at the correct stage of ripeness before it is picked.
Field Spot and Tendril Indicators
The field spot (which is the spot where the melon rested on the ground) should turn from a white or cream color to dark yellow as the watermelon ripens. A perfectly ripe watermelon will turn from shiny to dull green.
Using a Refractometer for Brix Testing
When watermelons appear close to ripeness, the grower will test the percentage brix with a refractometer. The brix is a measurement that correlates with how sweet a watermelon is. As the watermelon ripens, it gets sweeter, so the brix can be a good indicator of the level of ripeness.
Timing and Method of Harvest
Finally, the watermelons are ripe and ready to pick. The vines are turned for harvest, exposing the fruit to crews that hand-pick the ripest ones in the field. Truckloads of melons are taken directly to fresh markets or a packing shed.
Post-Harvest Handling and Distribution
At the packing shed, they are graded and packed for shipment to grocery stores, where consumers purchase and take them home to prepare for their tables. Peak harvest season here in SC is in the month of July.
Watermelon slices ready to enjoy.
Anna Sarah Hill, ©2025, Clemson Extension
Nutrition Benefits: Why Two Slices Are Okay
Next time you cut up a watermelon to set on your table, contemplate how it grew and the effort, time, and care the grower put into growing the perfect melon.
Now, take a bite, let that delicious flavor burst into your mouth. As the sweet juice trickles down your throat, reflect on how far watermelons have traveled across centuries and their incredible transformations from a wild, bitter weed to a cultivated, easy-to-eat, delightful and refreshing treat. Tempted to eat a second slice? Go ahead! Watermelons are low in calories, high in vitamins, and loaded with nutrients. The perfect rehydrater to beat the summer heat!
Additional Resources
Watermelon Nutrition Facts & Information
Athletes | SC Watermelon Association
Fresh Facts | SC Watermelon Association
More Melons on MyPlate! | Home & Garden Information Center
Nutrient Density | Home & Garden Information Center
Watermelon Nutrition Facts and Benefits | N.C. Cooperative Extension
Planting and Pest Information
Watermelons | Home & Garden Information Center
Cucumber, Squash, Melon & Other Cucurbit Insect Pests | Home & Garden Information Center
Cucumber, Squash, Melon & Other Cucurbit Diseases | Home & Garden Information Center
