Heirloom Organic Black Diamond Watermelon Seeds (15)
Black Diamond Watermelon
LightFull sun
Fruit size30 to 50 pounds
Matures75 to 90 days
Plant spacing36 to 60 inches apart
Plant sizeLong vine
Heirloom. Black Diamond is a classic oblong watermelon with a black-green rind covering bright red, crisp, flavorful flesh. In the 1950s, Black Diamond was a very popular home garden variety. Fruits have gray-black seeds (perfect for seed spitting contests) and can grow quite large. In Arkansas, where it’s rumored to have been developed, local gardeners recommend this melon for greased watermelon contests: Simply grease the melon, place it into a child’s plastic swimming pool, and get ready for some fun as the kids chase it and try to grab it!
Drought-resistant and prolific.If you'd like to grow especially large "Black Diamond" fruit, use a technique called culling, in which you choose the fruit you allow to grow and remove extras from each plant. Once you start seeing small, new watermelons appearing on a plant, pick a few healthy-looking specimens and remove some of the others, or, if you're looking for extra-giant melons, leave only one or two per plant. To help ensure your chosen fruits do well and mature successfully, add a layer of sand under each to help rain drain away and keep the melon's surface intact and clean. You could also give your growing fruit protection from scalding sun by pushing metal hoops into the soil around each melon and draping them with burlap.Size Versus Number
The "Black Diamond" watermelon cultivar is an old, open-pollinated variety. Also called "Cannonball" or "Florida Giant," its fruits are almost round in shape, with a slightly ribbed, dark green rind that's tough and solid, helping protect the fruit from damage. It's a high-yielding variety, dependably producing many fruits, that maximizes fruit production when given ideal growing conditions. If you're interested in extra-big, world class watermelons, you can harvest fruits that weigh up to 50 pounds from a "Black Diamond" plant by using methods that lead to fewer but bigger fruits.
Water and More Water
Like most melons, "Black Diamond" watermelon grows best in a spot that gets full sun for most of the day. It also needs fertile soil, but you can increase your soil's fertility by amending it with compost a week or two before planting. Like all watermelons, about 95 percent of a "Black Diamond" fruit's weight is water. Because of this, the plant needs regular, deep watering, especially during its first month in the garden, when fruit is beginning to set. Give the plant 1 to 2 inches of water each week, using drip irrigation if possible, as this allows moisture to seep slowly and deeply into the soil.