How to Grow Watermelon: Complete Guide

• •In cool climates with short summers, start watermelon seeds indoors 2 to 3 weeks before your last frost date and set transplants out about two weeks after that date, once the soil has warmed to at least 65°F (18°C)—ideally 70°F (21°C) or warmer.
• •In warmer long-season climates, sow directly outdoors 1 to 2 weeks after the last frost, again when soil temperature has reached at least 65 to 70°F.
• •Seeds should be sown 1/2 to 1 inch deep in the garden and 1/4 to 1/2 inch deep in pots.
• •Direct seed 4 to 6 seeds in each raised hill, thinning later to 2 to 3 strong seedlings per hill.
• •Handle transplants with extreme care because the roots are fragile and the vine resents disturbance; biodegradable peat or paper pots reduce transplant shock.
• •Black plastic or mulch laid over the bed before sowing warms the soil and speeds early growth.

📅 View the full zone-by-zone planting guide

1. 1

   Prepare fertile, warm, well-drained hills

   • •Choose a full-sun, open site and build raised hills or mounds 2 to 3 feet apart in 5-foot-wide rows, with rows at least 6 feet apart; each vine can sprawl over up to 20 square feet.
   • •Mix aged manure, compost or seaweed into each mound and rake the soil loose, correcting pH to 6.0 to 7.5.
   • •In cool regions, lay black plastic over the bed two weeks before planting to warm the soil, and cut planting holes through it.
   • •Rows on raised ridges drain well and hold the sun's heat longer than flat ground.
2. 2

   Sow seeds direct or start transplants indoors

   • •After the soil reaches at least 65 to 70°F (18 to 21°C), place 4 to 6 seeds 1/2 to 1 inch deep in each hill, spaced about an inch apart.
   • •In cool climates, start seeds 1/4 to 1/2 inch deep in biodegradable pots 2 to 3 weeks before last frost, keeping the medium at 75 to 85°F until sprouting.
   • •Plant those tender-rooted transplants directly into the hill without disturbing the root ball, and remove any dead or weak seedlings.
   • •Keep row covers in place until both male and female flowers open so pollinators can reach them.
3. 3

   Thin seedlings and guide the vines

   • •Once seedlings establish their first true leaves, thin each hill to the two strongest plants, snipping the rest at soil level rather than pulling to avoid root damage.
   • •Allow vines to sprawl naturally across the mulch; train runners away from neighboring crops so leaves receive full sun and air circulates between plants.
   • •Mulch the soil with straw or plastic beneath developing melons to lift them off wet ground and prevent rot and soil-borne disease.
4. 4

   Water, mulch and feed through fruit set

   • •Water the base of vines in the morning, providing 1 to 2 inches weekly until fruit begins swelling.
   • •Side-dress early growth with a balanced fertilizer, then shift to a higher-phosphorus, higher-potassium feed once female flowers appear.
   • •Keep mulch around hills to conserve moisture and suppress weeds, and slide cardboard or straw under each melon as it enlarges so it does not sit directly on damp soil.
   • •Stop heavy irrigation as the fruit ripens to build sweetness and reduce rind splitting.
5. 5

   Support pollination, harvest ripe melons and save seed if desired

   • •Both male and female flowers must be visited by bees to set fruit; avoid insecticides during bloom and, if bee activity is low, hand-pollinate by brushing a male flower's anthers onto a female flower's center.
   • •Watch for the ripening signs—yellow ground spot, brown tendril and hollow thump—and cut fruit with a knife.
   • •For seed saving, follow the fermentation method in the FAQ, reserving seed only from open-pollinated heirloom varieties because hybrids will not come true.

• Choose a very large, deep container for dwarf or bush types:
  • •Standard vines need too much room for pots, but compact bush varieties such as 'Sugar Baby' can grow in a 15 to 20-gallon container at least 18 inches wide and deep, with drainage holes.
  • •Fill it with rich, compost-amended potting mix and place it on a sunny patio where reflected heat ripens the fruit; a sturdy trellis or sling may support hanging melons so the vine can climb rather than spread.
• Water, feed and shelter container vines:
  • •Pots dry fast in wind and sun, so check daily and keep the root ball evenly moist, reducing water only as fruit ripens.
  • •Feed with dilute balanced fertilizer through vine growth and switch to a blossom-and-fruit feed once flowers open.
  • •Move the container out of cold wind, tie vines to a support, and hand-pollinate flowers if the patio lacks bees.

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  Thin side runners to concentrate fruit on the main vine

  • •Heavy pruning is not required for watermelon, but restricting the plant to one or two main vines and pinching off early side runners focuses energy into fewer, larger melons.
  • •Do this while vines are young, cutting end buds before lateral shoots become long vines, and remove any damaged or yellowed leaves that block airflow at the crown.
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  Fruit thinning and stem harvest cuts

  • •On a vigorous vine, leave the best 2 to 3 well-spaced fruits and remove misshapen or damaged young melons so the remaining fruit reaches full size and sweetness.
  • •At harvest, use a sharp knife to cut the stem close to the fruit rather than twisting, which can tear the vine and introduce disease wounds.

• •Most varieties mature 70 to 100 days after planting, with the fruit ripening over roughly a two-week window; watermelons do not sweeten further after picking, so timing matters.
• •Ripe signs include a dull rather than bright sheen on the rind, a creamy yellow (not white) ground spot where the melon rests on the soil, a hollow sound when thumped, and the tendril nearest the fruit stem turning brown and drying.
• •Cut the stem close to the melon with a sharp knife rather than twisting it off.
• •Store uncut fruit for about 10 days; once cut, keep it wrapped in the refrigerator for about four days.