{"product_id":"black-diamond-heirloom-watermelon-seeds","title":"Black Diamond, Heirloom Watermelon Seeds","description":"\u003ch2\u003eBlack Diamond, Heirloom Watermelon Seeds — The 1950s Giant Classic With Dark Blue-Black Rind, Bright Red Flesh, and a Built-In Yellow Belly Ripeness Indicator, 30–50 lbs\u003c\/h2\u003e\u003cp\u003eBlack Diamond (\u003cem\u003eCitrullus lanatus\u003c\/em\u003e) is one of the great heirloom watermelons of the American garden — a classic oblong giant with a strikingly dark blue-black rind covered in prominent creases, crisp bright red flesh, and a built-in ripeness signal that home gardeners have relied on for generations. As the melon ripens, the underside where it rests on the ground turns from white to a rich yellow — the iconic “yellow belly” that tells you harvest time has arrived. Fruits grow large, often 30–50 lbs and 19×17 inches, with a tough rind that stores and ships exceptionally well. Bright red, sweet, and satisfying — a summer watermelon that delivers everything you want. 90–95 days.\u003c\/p\u003e\u003ch3\u003eWhy Grow Black Diamond?\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e30–50 lb oblong giants\u003c\/strong\u003e — dark blue-black rind with prominent creases, dramatic and beautiful\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBuilt-in yellow belly ripeness indicator\u003c\/strong\u003e — no guessing when to harvest\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBright red, crisp, sweet flesh\u003c\/strong\u003e — classic summer watermelon flavor\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTough rind stores and ships exceptionally well\u003c\/strong\u003e — great for markets and extended home use\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHeat tolerant\u003c\/strong\u003e — thrives in hot summer conditions\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eClassic seeded variety\u003c\/strong\u003e — perfect for seed-spitting contests and seed saving\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOpen-pollinated heirloom\u003c\/strong\u003e — save seed year after year\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eKnowing When to Harvest\u003c\/h3\u003e\u003cp\u003eBlack Diamond’s “yellow belly” is your primary ripeness cue — the spot where the melon rests on the soil turns from creamy white to rich golden-yellow when fully ripe. Confirm ripeness by checking the tendril closest to the fruit stem: when it has dried and turned brown and curled, the melon is ready. The rind will also dull from shiny to matte. Thumping should produce a deep, hollow thud. Do not rely on size alone — wait for the yellow belly and dried tendril together for peak sweetness.\u003c\/p\u003e\u003ch3\u003eIn the Kitchen\u003c\/h3\u003e\u003cp\u003eSlice chilled for classic summer eating. Cube into fruit salads and salsas. Blend into agua fresca or watermelon lemonade. Grill thick slices briefly for a caramelized summer side. The large seeded fruits make for classic backyard seed-spitting fun. Scoop the flesh and freeze in cubes for smoothies and cocktails all summer long.\u003c\/p\u003e\u003ch3\u003eGrowing Notes\u003c\/h3\u003e\u003cp\u003eDirect sow ½–1 inch deep outdoors after last frost when soil has warmed to at least 70°F, or start indoors 3–4 weeks before transplanting. Space plants 30–60 inches apart in rows 7–10 feet apart — Black Diamond needs ample room to sprawl. Full sun. Fertile, well-draining soil. Keep consistently moist during fruit development. Black plastic mulch warms soil and conserves moisture. Avoid overhead watering. Feed with a balanced fertilizer at planting; switch to low-nitrogen once vines run. One plant can produce 2–3 giant melons in a season.\u003c\/p\u003e\u003ctable\u003e\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eDays to Maturity\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e90–95 days\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eDays to Germination\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e4–12 days\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eFruit Size\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e30–50 lbs, 19×17 inches, oblong\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eRind\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eDark blue-black with prominent creases; tough\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eFlesh\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eBright red, crisp, sweet\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eRipeness Cue\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eYellow belly develops; nearest tendril dries and browns\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSeeds\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eSeeded (classic gray-black seeds)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eStorage\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eStores well — tough rind extends shelf life\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003ePlant Spacing\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e30–60 inches\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eRow Spacing\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e7–10 feet\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003ePlanting Depth\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e½–1 inch\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSoil\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eFertile, well-draining; pH 6.0–6.8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eLight\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eFull sun\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eUSDA Zones\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e3–10 (heat-loving annual)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eLatin Name\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cem\u003eCitrullus lanatus\u003c\/em\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eType\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eHeirloom, Open-Pollinated, Non-GMO, Annual\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\u003c\/table\u003e\u003cp\u003e\u003cem\u003ePacked and shipped by Box Garden Seeds LLC — heirloom seeds grown without GMOs, selected for flavor, resilience, and your garden’s success.\u003c\/em\u003e\u003c\/p\u003e","brand":"Box Garden Seeds LLC","offers":[{"title":"0.8 g \/ 25+ Seeds","offer_id":42680340447366,"sku":"MSS\/C4-25-90-222-28","price":4.25,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/2669\/3330\/files\/il_fullxfull.7658516911_s0pk.jpg?v=1770127898","url":"https:\/\/bgseedsllc.com\/products\/black-diamond-heirloom-watermelon-seeds","provider":"Box Garden Seeds LLC","version":"1.0","type":"link"}