How to Grow Seedless Watermelons

Seedless watermelons are popular fruits since you can eat them without worrying about those pesky black seeds. While you can always buy them from your local supermarket, you can also grow them in your own backyard! By planting your seeds and caring for your plants throughout the summer, you can have seedless melons ready for harvest in early fall.

Part 1
Part 1 of 3:

Planting Watermelons

  1. Seedless and seeded watermelons must pollinate with one another in order to produce seedless fruit. Visit your local plant nursery or find the seeds online. Triploid seeds will produce seedless watermelons while diploid seeds produce seeded melons.
  2. Watermelon seedlings cannot survive in the ground if there’s frost. Look up the last frost date for your area. Planting your seeds indoors 3 weeks in advance of the date allows the seedlings to establish so they can survive outdoors. [1]
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  3. Buy a well-drained potting soil meant for growing fruit or make your own. Use a spray bottle to slightly moisten the soil. Pack your soil into the cells so it’s level with the top of the tray. [2]
    • Mix components like sand and perlite into your soil to make sure it’s well-draining.
    • If you can squeeze a handful of soil and water runs out, the soil is too wet for seedless watermelons to germinate.
  4. Heat mats help bring soil to a suitable temperature so they can germinate easily. Plug in the heat mat and set the temperature to 85 °F (29 °C). Place your cell trays on top of the mat to heat the soil. [3]
    • Heat mats can be purchased online or at your local gardening store.
    • Cover the mat with a growing chamber if you want to retain the heat. Growing chambers are large plastic coverings that sit on top of your mat to help incubate your plants.
  5. Push the seeds into the soil using your finger. Plant the diploid seeds in one tray and the triploid seeds in the other. Sowing the seeds so the pointed end faces up helps the seed coat break when the sprouts emerge. [4]
    • Sow both the diploid and triploid seeds at the same time so they can germinate and grow simultaneously.
  6. Put room temperature water into a spray bottle and lightly mist your seeds once you plant them. If your soil feels dry when you stick your finger in it to the first knuckle, water it again. [5]
    • Avoid using cold water since it could affect the overall temperature of the soil.
  7. Keep the trays on the heat mat near a south-facing window so the soil temperature remains constant. Keep thin curtains drawn so the sun doesn’t dry out your soil. You should see sprouts form after 2 or 3 days. After that, you can expose the seedlings to full sunlight. [6]
    • Cover your tray with a thin poly sheet to trap the moisture in the soil. Poly sheets can be purchased at your local gardening store.
  8. Look for thin, smaller seedlings, and cut them at the base with a small pair of gardening scissors. Avoid pulling the plant out since it could damage the roots on your stronger seedlings. [7]
    • If you only placed 1 seed in each cell, you don’t need to thin out your seedlings.
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Part 2
Part 2 of 3:

Transplanting and Caring for Your Plants

  1. Look for plants with 2-3 leaves growing from the stem. Carefully squeeze the cells in the tray to loosen the soil so your plants are easier to remove without damaging them. [8]
    • True leaves will look round with multiple lobes.
    • Seedlings with more than 4 true leaves are susceptible to transplant shock, which could reduce your yield and melon size.
  2. Make sure your soil temperature is at least 65 °F (18 °C) in the morning and there’s no risk of frost. Dig holes slightly larger than the root systems of your plants and place your seedlings in the ground. Press firmly on the soil around them to ensure the roots have good contact.
    • Always plant at least 1 diploid seedling for every 3 triploid seedlings you have.
    • If you’re planting your melons in separate rows, space them 6 feet (1.8 m) apart from one another.
  3. Buy a phosphorus mix from your local plant nursery or gardening store. Sprinkle the fertilizer on the sides of your plant, using ½ cup (113 g) for every 10 feet (3.0 m). Immediately water your melons so the fertilizer doesn’t damage them. [9]
    • Avoid using nitrogen-rich fertilizers since these could make your fruits have a hollow interior.
  4. Bees, moths, and butterflies are the most common pollinators, and pollination is necessary for seedless watermelons to produce fruit. Leave patches of fallen branches or nesting locations so pollinators can live right in your yard. Keep a variety of plants and flowers in your yard to provide different food sources.
    • Avoid or limit using pesticides since they could harm pollinators.
  5. Use a gentle setting on a hose attachment to water your plants as they grow. Keep the soil moist, but not soaking wet. [10]
    • Don’t water during the last week before the fruits ripen since overwatering can make your melons taste bland.
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Part 3
Part 3 of 3:

Harvesting Your Melons

  1. Seedless watermelons usually take between 85-100 days to fully ripen. If the tendrils connected to the melons are brown and dying, your melons are ready. You can also look at the bottom of your melons for a yellow patch, or ground spot, to determine if they’re ripe. [11]
    • Flick the melons and listen for a deep, solid thump noise. If the sound is high-pitched or tinny, your melon isn’t ready.
  2. Once your melons are ripe, you should be able to easily pull them off the vine. When one watermelon is ready to be picked, the others on the same plant will either be ripe or ripen within the next few days.
  3. Store your watermelons whole for up to 2-3 weeks at room temperature. Store the watermelons in your kitchen or basement until you use them. If you cut the melon, make sure to refrigerate any pieces you don’t eat. [12]
    • Cut your watermelon and freeze the pieces for up to 12 months.
    • Put watermelon in a blender with ice to make a watermelon slushie to cool down on a hot summer’s day!

    Watermelon Slush Instructions

    Mix 5 cups (760 g) of diced watermelon, 2 tablespoons (24 g) of sugar, the juice from 1 lime, and 1 cup (217 g) of ice in your blender. Serve it right out of the blender cold! [13]

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  • Question
    Will this produce both the seeded watermelons and seedless ones?
    Community Answer
    Yes. The seedless ones don't develop correctly without a seeded variety to pollinate with.
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      Video

      Tips

      • Seedless watermelons need to be grown with seeded watermelons or else they won’t produce fruit.
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      Things You’ll Need

      • Triploid and diploid watermelon seeds
      • Cell trays
      • Potting soil
      • Heat mat
      • Growing chamber
      • Spray bottle
      • Garden scissors
      • Fertilizer

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      References

      1. ↑ http://www.johnnyseeds.com/growers-library/vegetables/watermelon-triploid-seedless-production.html
      2. ↑ http://www.johnnyseeds.com/growers-library/vegetables/watermelon-triploid-seedless-production.html
      3. ↑ https://youtu.be/jQAVZfodxt0?t=1m11s
      4. ↑ http://www.johnnyseeds.com/growers-library/vegetables/watermelon-triploid-seedless-production.html
      5. ↑ http://www.johnnyseeds.com/growers-library/vegetables/watermelon-triploid-seedless-production.html
      6. ↑ http://www.johnnyseeds.com/growers-library/vegetables/watermelon-triploid-seedless-production.html
      7. ↑ http://www.johnnyseeds.com/growers-library/vegetables/watermelon-triploid-seedless-production.html
      8. ↑ http://www.johnnyseeds.com/growers-library/vegetables/watermelon-triploid-seedless-production.html
      9. ↑ http://www.johnnyseeds.com/growers-library/vegetables/watermelon-triploid-seedless-production.html
      1. ↑ http://www.johnnyseeds.com/growers-library/vegetables/watermelon-triploid-seedless-production.html
      2. ↑ http://www.johnnyseeds.com/growers-library/vegetables/watermelon-triploid-seedless-production.html
      3. ↑ https://bonnieplants.com/blogs/how-to-grow/growing-watermelons
      4. ↑ https://damndelicious.net/2014/05/24/watermelon-slush/

      About this article

      Article Summary X

      To grow seedless watermelons, you'll need to plant both triploid and diploid watermelon seeds so that they pollinate with each other and produce seedless fruit. Once you have both kinds of seeds, start them indoors 3 weeks before the last expected frost in your area. Then, after the last frost, transplant the sprouted seedlings into the ground outside, making sure you have 3 triploids for each diploid. To attract pollinators, keep a variety of plants and flowers nearby, and avoid using pesticides. After 3 months, you should be able to harvest your seedless watermelons. To learn how to care for watermelon seedlings, scroll down!

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      Reader Success Stories

      • Ana Lutchman

        Jun 17, 2016

        "The fact that I have to plant seeded watermelon next to seedless so they can pollinate was a great help, I ..." more

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