Watermelon

Citrullus lanatus · Gourd family (Cucurbitaceae)

At a glance
Hardiness zones	3 to 11
Sun	full sun
Water	moderate
Life cycle	annual
Frost	Tender: killed by frost
Soil pH	6.0–6.5
Spacing	24 to 36 inches
Days to harvest	70 to 90 days
Soil temperature to plant	at least 65°F

About Watermelon

Watermelons are sprawling vines that need heat, room and time to ripen sweet fruit. They are more sensitive to cold than cantaloupe, so warm soil and black plastic mulch help in cooler areas.

Grown as a warm-season annual in every zone; it is killed by frost, so plant it out after the danger of frost has passed. It prefers average temperatures of 70 to 85F.

When to plant

Timing is counted from your average last spring frost (and first fall frost). Sow & Tell works out the actual dates for your ZIP code.

Start seeds indoors: 2 to 4 weeks before the last frost
Set out plants: 2 to 3 weeks after the last frost
Sow seeds outdoors: 2 to 3 weeks after the last frost

Days count from seeding (Clemson notes 85 to 90 days from transplant for most varieties); fruit ripens about 35 days after it sets. Rows are usually 6 to 8 feet apart.

Soil

Well-drained sandy loam; most roots are in the top 12 inches.

Follow a soil test and keep pH 6.0 to 6.5; work in compost or well-rotted manure, and without a test add about 30 lb of 5-10-10 per 1,000 sq ft (about 3 lb per 100 sq ft) before planting.

Feeding

before the vines start to run: nitrogen fertilizer such as 34-0-0 or calcium nitrate (15.5-0-0). Use about 1 lb of 34-0-0 or 2 lb of calcium nitrate per 100 ft of row beside the plants and water it in.
after bloom, when fruit is forming on the vine: nitrogen fertilizer such as 34-0-0 or calcium nitrate (15.5-0-0). Side-dress a second time beside the row and water it in.

Too much nitrogen gives extra vine and less fruit; soil below pH 6.0 can give yellow plants that set little fruit.

Harvest

Look for several signs together: the curly tendril nearest the fruit turns brown and dry, the rind turns dull, and the spot where the melon rests changes from pale green to creamy yellow. Melons do not get sweeter after picking.

Each melon is picked once, when the tendril nearest it browns, the rind dulls and the underside turns creamy yellow; melons on a vine don't all ripen at the same time.

Varieties (51)

Variety	Type	Days	Notes
Stone Mountain	Heirloom, large		Sweet red flesh. Thick, tough dark green rind; fruit about 35 to 40 pounds.
Kleckley Sweet	Heirloom, long	85 days	Oblong fruit of 25 to 40 pounds with a thin, glossy dark green rind, medium-red flesh and large white seeds.
Blacktail Mountain	Icebox	76 days	Sweet orange-red flesh. Round fruit of 6 to 12 pounds with a dark green rind and faint darker stripes.
Minilee	Icebox		Small round fruit of 5 to 8 pounds with a Charleston Gray-like rind, firm red flesh, a thin but tough rind and very small seeds.
Tiger Baby	Icebox	80 days	Round to slightly oval fruit of about 7 to 11 pounds with dark green stripes on gray-green.
Jade Star	Icebox (small seeded)		Sugar Baby-type melon of about 10 to 12 pounds with a very dark green rind and deep red flesh.
Mickylee	Icebox (small seeded)		Round fruit of 8 to 12 pounds with a gray-green rind and dark red flesh. Resists fusarium wilt and anthracnose.
Petite Sweet	Icebox (small seeded)	75 days	Blocky round fruit of 5 to 10 pounds with pinkish-red flesh and few, small seeds. Resists fusarium wilt and anthracnose.
Sugar Baby	Icebox (small seeded)	77 days	Small, round fruit of about 8 to 10 pounds with a solid dark green rind and red flesh.
Bush Sugar Baby	Icebox, compact vine	75 days	A compact-vined version of the Sugar Baby type.
New Queen	Icebox, orange flesh	63 days	Small, oval, striped fruit of about 4 to 5 pounds with orange flesh.
Yellow Doll	Icebox, yellow flesh, hybrid		Round, yellow-fleshed fruit of about 5 to 7 pounds.
Golden Crown	Icebox, yellow rind	70 days	Small round fruit of about 2 to 4 pounds whose rind turns bright gold when ripe; pink-red flesh.
Jubilee II	Large, long		Looks and grows like Jubilee but was selected for stronger Fusarium wilt resistance.
Patriot	Large, long	80 to 85 days	Cylinder-shaped fruit of about 22 to 26 pounds with a light green rind, wide medium green stripes and red flesh.
Fiesta	Large, long (Allsweet type, hybrid)		High in sugar. Fruit of 22 to 25 pounds with a dark green rind, light green stripes and bright red flesh. Resistant to Fusarium wilt race 0 and tolerant of race 1 and anthracnose.
Royal Majesty	Large, long (Allsweet type, hybrid)		Elongated fruit with thin, medium green stripes.
Calhoun Gray	Large, long (Charleston Gray type)	85 days	Bred from Calhoun Sweet and Charleston Gray. Resistant to anthracnose and Fusarium wilt races 0 and 1.
Prince Charles	Large, long (hybrid)	80 days	Hybrid Charleston Gray type that ripens earlier, grows larger and has stronger Fusarium wilt resistance than Charleston Gray.
Sentinel	Large, oblong (hybrid)		Oblong fruit of 20 to 27 pounds with a Crimson Sweet-style stripe. Cornell lists anthracnose resistance.
OrangeGlo	Large, orange flesh	85 days	Very large fruit (about 50 pounds) with a light green rind, dark stripes and orange flesh.
Dixielee	Large, round		Round fruit with Jubilee-type stripes, 18 to 22 pounds. Resistant to Fusarium wilt race 1 and anthracnose race 1.
Crimson Tide	Large, round (Crimson Sweet type)		Like Crimson Sweet with slightly darker stripes; fruit about 24 pounds. Resistant to Fusarium wilt and tolerant of anthracnose race 1.
Mirage	Large, round (hybrid)	85 days	Crimson Sweet-type hybrid that is more uniform and productive. Fusarium wilt resistant.
Top Gun	Large, round (hybrid)	83 days	Globe-shaped fruit of 21 to 24 pounds with broad dark stripes and bright red flesh. Cornell lists anthracnose and Fusarium wilt resistance.
Imagination	Round (Sugar Baby type)	82 days	Very dark, solid green rind and bright red flesh; fruit 12 to 14 pounds.
Black Diamond	Seeded	90 days	Open-pollinated seeded melon.
Congo	Seeded		Productive melon with good quality. Resists anthracnose.
Moon and Stars	Seeded (heirloom)	95 to 105 days	Sweet red flesh. Dark green rind speckled with bright yellow spots; brown seeds with black dots.
Royal Sweet	Seeded, blocky oval, hybrid	85 days	Bright red, crisp flesh. Blocky oval fruit of 20 to 25 pounds with a striped green rind. Tolerates fusarium wilt.
Sangria	Seeded, blocky oval, hybrid	87 days	Red-fleshed, blocky oval fruit of 20 to 26 pounds, dark green with a light stripe and small black seeds. Resists fusarium wilt and tolerates anthracnose.
Mardi Gras	Seeded, large, hybrid	86 to 90 days	Large fruit of 20 to 25 pounds. Resists anthracnose and fusarium wilt.
Allsweet	Seeded, long	90 days	Very sweet, firm flesh. Long, cylinder-shaped fruit with a broken-stripe rind and small dark seeds. Resists fusarium wilt and anthracnose.
Charleston Gray	Seeded, long	85 days	Crisp and sweet, with light red flesh. Long fruit with a tough gray-green rind that ships well. Resists fusarium wilt and anthracnose and tolerates sunburn.
Jubilee	Seeded, long	95 days	Sweet, pink-red flesh. Large fruit of 35 to 40 pounds with a tough rind in narrow dark stripes on light green and black seeds. Resists fusarium wilt and anthracnose.
Georgia Rattlesnake	Seeded, long (heirloom)	90 days	Crisp, sweet, bright red flesh. Very long fruit of 25 to 30 pounds, light green with irregular dark green stripes; white seeds with dark tips.
Royal Jubilee	Seeded, long, hybrid	95 days	Bright red, crisp flesh. Elongated fruit with a light green rind and dark stripes. Tolerates anthracnose and fusarium wilt.
Tendersweet Orange	Seeded, orange flesh	85 days	Oblong fruit with a dark green, mottled-stripe rind and orange flesh.
Dixie Queen	Seeded, round (heirloom)	90 days	Round fruit of 30 to 40 pounds with narrow dark stripes, pink flesh and small white seeds.
Crimson Sweet	Seeded, round-blocky	85 days	High in sugar with fine-textured red flesh. Blocky round fruit of 20 to 30 pounds, light green with dark stripes and small dark seeds. Resists fusarium wilt and anthracnose.
Desert King	Seeded, yellow flesh	85 days	Round to slightly oblong fruit with a pale green rind and deep yellow flesh; resists sunburn and handles drought.
Yellow Baby	Seeded, yellow flesh, hybrid		Round, yellow-fleshed fruit of about 9 to 12 pounds, light green with dark stripes.
Tiffany	Seedless (triploid hybrid)		Round, striped seedless fruit up to about 20 pounds with solid, evenly red flesh.
King of Hearts	Seedless (triploid)		Blocky, slightly oblong seedless melon, striped green, with bright red flesh.
Millionaire	Seedless (triploid)		Red-fleshed, oblong fruit of about 13 to 20 pounds.
Sweet Gem	Seedless (triploid)		Red-fleshed, round fruit of about 13 to 16 pounds.
Tri-X 313	Seedless (triploid)	85 days	Oval, red-fleshed seedless melon with a light green rind mottled in dark stripes.
Solitaire	Small	85 days	Round fruit of 5 to 7 pounds with a mottled dark green rind and deep red flesh.
Golden Midget	Small seeded (early)	70 days	Small melon whose rind turns golden orange when ripe, a handy ripeness signal; dark seeds.
New Hampshire Midget	Small seeded (early)		Very early, small oval melon with a gray-green rind, red flesh and black seeds.
Early Moonbeam	Small, yellow flesh	78 days	Small fruit around 4 to 7 pounds with dark green stripes on light green and yellow flesh.

Good neighbors

Winter squash and pumpkin

UMN and Illinois Extension note Blue Hubbard squash can be used as a trap crop to lure cucumber beetles away from other vine crops.

Pests to watch for

Cucumber beetles, Squash bug, Aphids, Twospotted spider mite, Whiteflies, Leafminers, Root-knot nematodes, Pillbugs and sowbugs, Squash beetle, Mice (house mice and deer mice), Raccoon, Broad mite, Seedcorn maggot, Melonworm

Diseases and problems

Anthracnose, Gummy stem blight, Powdery mildew, Fusarium wilt, Blossom end rot, Poor pollination, Ozone injury, Sunscald, Frost and freeze injury, Angular leaf spot, Verticillium wilt, Mosaic viruses, Downy mildew, Damping-off, Southern blight, Sooty mold, Cucumber mosaic, Zucchini yellow mosaic, Watermelon mosaic, Tomato and tobacco ringspot

In the kitchen

Eaten fresh in slices, fruit salads, juices and frozen treats.

Keeping it: Keep whole melons cool (about 55F) for up to 2 weeks; long chilling below 50F hurts them. Rinse the rind before cutting, then refrigerate cut melon and eat it within 5 days.

Pets: Not listed as toxic by the ASPCA

Sources

Photo: Photo: Keith Weller, USDA ARS, Public domain (USDA ARS), via Wikimedia Commons. Photo resized for the web.

Planting dates and advice are general guidance; check with your local Cooperative Extension office for your area.