GardenWatermelon variety
Black Diamond Watermelon
✓ In your garden
Black Diamond is a picnic watermelon, ready in about 90 days. It makes big picnic-sized melons. Watermelons need a long, hot summer, full sun, and room to run — plant well after frost. It’s ripe when the curly tendril nearest the fruit dries brown and the ground spot turns creamy yellow.
“A sweet summer watermelon for a long, hot season.”
Growing basics — shared by every watermelon
Black Diamond grows like any other watermelon. The full picture — how deep to plant, spacing, feeding, pests, harvest — lives on the Watermelon page so it's maintained in one place.
- Sun
- Full Sun
- Spacing (in row)
- 36–60 in
- Row spacing
- 72–96 in
- Planting depth
- 1–2 in
- Soil pH
- 6–7
- Water
- Moderate
What is Black Diamond good for?
- Fresh & chilledStraight from the fridge. Great
- Juice & agua frescaBlend and strain. Great
- Pickled rindA Southern tradition — for the rind. Skip it
From how it grows — kitchens vary.
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Want the full 10/50/90% odds + nearest stations? Open the frost tool →When to plant Black Diamond in your zone
Zone 6bGreenhouse or cover on: your start slides ~4 weeks earlier and your harvest stretches ~3 weeks later (shown striped).
Planting seeds straight in the ground only works where the season's long and warm — most gardeners start seeds indoors or buy young plants, or you'd pick your first tomato right as frost hits.
Comfortable — first ripe fruit lands around late Jul, well before your typical frost (~late Oct).
- Start seeds indoors
- mid Mar – late Mar
- Toughen up outside
- mid Apr – late Apr
- Move plants outside
- late Apr – early May
- Plant seeds outside
- late Apr – early May
- Growing
- early May – late Jul
- Picking
- late Jul – early Aug
Typical dates for zone 6b — set your zone or ZIP above for yours.
Growing Black Diamond — the things that trip people up
- Melons are heat-lovers with big appetites — give them full sun, rich soil, room to sprawl, and a long warm season. In short-season areas, start them indoors and use black plastic or a cover to warm the soil.
- Ease off the water as the fruit ripens — too much late water dilutes the sugar. Judge ripeness by the dried tendril and the creamy-yellow ground spot, not by thumping.
Black Diamond watermelon at a glance
| Type | Picnic |
|---|---|
| Days to ripe | 90 days after you plant it outside |
| Color | Red |
Extra fields from seed-catalog listings and university growing guides. Days to ripe and disease resistance shift with your climate and seed source — double-check with your local extension office before you buy.
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Common questions about Black Diamond
How long does Black Diamond take to grow?
About 90 days, and it wants that whole stretch warm — start early in short-season areas.
How do I know Black Diamond is ripe?
When the curly tendril nearest the fruit dries brown and the spot where it sits on the ground turns from white to creamy yellow.
Browse more watermelon varieties →