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The Rare Black Diamond Yellow Belly Watermelon

Watermelons are an interesting fruit, and they have come a long way since the first watermelons were brought to the United States in the 16 and 1700s. There are now hundreds of watermelon varieties, including many that are strains of other varieties.

One such watermelon variety is the Black Diamond Yellow Belly Watermelon. If you want to know everything about this watermelon variety, including how to plant, care for, grow, and harvest it, you’ve come to the right place.

Characteristics of the Black Diamond Yellow Belly Watermelon

Watermelon that is very similar to the Black Diamond Yellow Belly Watermelon

In addition to having one of the biggest names of any watermelon variety, the Black Diamond Yellow Belly Watermelon is also one of the most interesting. It’s an open-pollination, heirloom variety that typically gets passed down from generation to generation as a sort of family recipe.

We’re not exactly sure how or when it was first cultivated or who had the honor, for that matter. What we know is that it’s a strain of its parent watermelon, the Black Diamond, cultivated in the mid to late 1940s in Arkansas.

What we do know, however, is that the black diamond yellow belly is a large melon that takes longer to mature than most other varieties. It’s also very popular with home growers and small farms but isn’t popular enough for widespread commercial use.

Shape and Size

Black Diamond Yellow Belly Watermelons are among the largest melon varieties on the market. They grow on vines up to twenty feet long and produce thousands of seeds.

The melons themselves are typically between sixteen and twenty inches long and up to sixty inches in circumference. They often weigh between thirty and fifty pounds, which is huge but not quite as big as their parent plant, the black diamond watermelon.

Black Diamond Yellow Belly Watermelons also tend to be more round and rotund than their black diamond counterpart. The yellow belly strain isn’t quite as long and oblong and is shaped more like a pumpkin, while its parent plant is shaped more like a football.

External Color

Another key difference between the two varieties is their color. While both varieties have dark green skin with few stripes and striations, the black diamond yellow belly melon has a large yellow patch on its belly, which is where it gets its name.

The yellow patch is larger and starker than the yellow you typically find on melons when they are ready to harvest. Additionally, black diamond watermelons can sometimes have bellies that turn white instead of yellow.

Internal Color

Bright red watermelon flesh

The flesh of this watermelon variety is bright red and is packed with hundreds or thousands of black and grey seeds.

Taste and Texture

Like most watermelons, the Black Diamond Yellow Belly has sweet, crispy flesh. However, it’s important to harvest it at the right time to maintain consistent taste and color throughout the flesh of the melon.

Because of how large it is, consistency is tough but attainable with a little practice and careful attention. These melons are between 85 and 95% water, which means they’re slightly juicier than most other melon varieties.

Health Benefits

Like all watermelon varieties, Black Diamond Yellow Belly Watermelons are a healthy snack and offer several benefits.

  • Vitamin C
  • Potassium
  • Cartenoids
  • Decreases cholesterol for better heart health
  • Contains mostly water, making them great for hydration

Because this melon variety is an open pollinator, it makes a great addition to larger fruit and vegetable gardens. It attracts bees and insects that help pollinate other plants and can greatly improve your garden.

Growing At Home

Because Black Diamond Yellow Belly Watermelons aren’t available on a large scale in markets and grocery stores, you’ll likely have to grow them at home to try them out.

Dark Watermelon Growing on Vine

These plants do best in hardiness zones four through eleven, but they can also handle zones one through three. Black Diamond Yellow Belly Watermelons are slightly hardier than their parent strain but still require the same amount of water, warmth, and care as all watermelons.


Your soil is the first and biggest thing to remember when planting Black Diamond Yellow Belly Watermelons. Watermelons can’t tolerate soil that’s colder than 70 degrees F or that is too alkaline.

Your soil should have a pH level of between 5.9 and 7.0, with 6.4 being perfect. The soil should also have excellent drainage, aeration, and moisture retention because watermelons need a ton of water.

Without adequate drainage and aeration, your watermelon plants are more prone to developing a water-related disease. To this end, loamy soil with a sandy texture is your best bet with Black Diamond Yellow Belly Watermelons.


In addition to loamy, nutritious soil, Black Diamond Yellow Belly Watermelons also need fertilizer heavy in nutrients such as phosphorous, magnesium, boron, and potassium. You should add fertilizer when you first plant the seeds and as prescribed from there on out.

It’s also a good idea to pad the soil’s surface with compost-heavy mulch roughly two inches thick.


Because of how big Black Diamond Yellow Belly Watermelons get and how long their vines are, it’s important to give them adequate space to grow. Ideally, you should plant your seedlings a minimum of four feet apart, but five or six feet is better.


You should prune your Black Diamond Yellow Belly Watermelon two times from when you plant it to when it reaches maturity. You only want four growing tips with these melons, so pinch back the least productive seedlings and allow the rest to flourish.


All watermelons consist mostly of water, but the black diamond yellow belly has a water content higher than most. As such, they need a ton of water throughout the planting and growing process.

As with most melon varieties, black diamond yellow belly melons need more water when you plant them. However, as the plants mature and get closer to harvest time, they don’t need quite as much water.

The main reason these melons need so much water is their leaves. The more leaves a watermelon has and the healthier they are, the sweeter and juicier the melon will be.

Your goal is to maintain soggy, moist soil without ever getting it muddy or too damp. Because this is difficult to do with hand-watering, the best watering method for Black Diamond Yellow Belly Watermelons is drip irrigation.


Watermelon in the sun

Like all watermelon varieties, Black Diamond Yellow Belly loves itself some sunshine. You should plant your melons in full sun, guaranteeing at least six to eight hours of sunlight per day.

Pests to Watch Out For

All watermelons tend to draw in pests and bugs, but black diamond is especially bad. They’re prone to attracting aphids, bees, predatory wasps, birds, deer, beetles, rabbits, and other bugs and rodents.

Common Watermelon Diseases

In addition to pests, there are various diseases to watch out for, including different strains of wilt, mildew, scab, and anthracnose. It’s also worth noting that parts of the Black Diamond Yellow Belly Watermelon plant are toxic to pets, so keep your dogs and cats away until after harvest.

Harvesting This Watermelon

Black Diamond Yellow Belly Watermelons are usually ready to harvest roughly eighty to 100 days after you plant them. Here are several clues to help you determine when your melons are ripe and ready to harvest.

  1. The tendril nearest the fruit will turn brown and wither.
  2. The fruit should sound hollow when you tap it.

Check our sister page for more information and clues about when and how to harvest your black diamond watermelons.

Where To Buy the Black Diamond Yellow Belly Watermelon

Because Black Diamond Yellow Belly Watermelons aren’t overly popular, they’re difficult to find in most areas. However, if you want to purchase 100% non-hybrid and non-GMO seeds to plant these melons at home, you can do so at Amazon.

Wrapping Up the Black Diamond Yellow Belly Watermelon

While its parent plant is more popular, the Black Diamond Yellow Belly Watermelon strain does it proud. It’s a large, hardy melon variety that produces delectable, sweet, juicy fruit.

If this article has you curious about watermelon plants, you can find all the information you need on our sister page dedicated exclusively to watermelon plants.