How to Grow Watermelon from Seed Indoors

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Have you tried growing watermelon from seed? This delicious fruit works out just fine in the backyard garden! Learn how to grow watermelon from seed for a yummy summertime harvest.

We had great fun growing watermelons from seed for the first time in 2021. (Our 2020 crop did not survive once I moved the watermelon planter away from its original location.)

This year’s watermelons were tiny but still delicious. I am excited to try growing more watermelon with my girls, who both love it.

I have some good tips on how to grow watermelon from seed that I can’t wait to share.

Let’s get started!

Baby Watermelon - how to grow watermelon from seed indoors
Baby Watermelon in our garden – Learn how to grow watermelon from seed indoors!

How do watermelons grow?

Like most cucurbits in the Cucurbitaceae family, watermelons are vining plants that grow in a rather sprawling manner. Once the plant begins vining out, you may notice watermelon flowers on the fines. Look for the flowers with a baby watermelon attached – these are the female watermelon flowers. If they get pollinated by the male flowers (those without the mini watermelons), the watermelon begins to grow.

What do watermelon seedlings look like?

Watermelon seedlings have a somewhat fuzzy, sandpapery texture. Their leaves feature a lovely shape made up of several lobes, usually three to five. Watermelon leaves are light to medium green, often with variegated hues that may even include a shimmery white.

The shape of the watermelon leaf makes this crop stand out from other cucurbits like cucumbers and zucchini. When they grow larger, watermelon vines also have fuzzy hairs.

When should you be planting watermelon seeds indoors?

Try planting watermelon seeds ahead of the last spring frost to ensure your watermelons grow to reach maturity. Start your watermelon seeds indoors 6 to 8 weeks before the last expected frost. This gives your melon plants some time to grow before transplanting them outdoors in the garden.

What do watermelons need to grow?

Watermelons need a lot of the same things that most young seedlings need to grow. Start watermelon seeds with quality soil, sunlight, and watering as needed. Lightly fertilize with nitrogen-based fertilizer when the vines begin spreading.

Why is my watermelon seedling dying?

If you notice your watermelon seedling is dying or failing, look for clues. Watering issues are usually to blame with seedling death in many cases. In particular with watermelons, damping off is a common occurrence, where the soil remains too wet and the plant ultimately dies from a fungal infection.

DIY: How to Grow Watermelon from Seed

Plan to plant watermelon seeds about a month and a half to two months before your area’s last frost. Watermelon seedlings can take up a lot of room, so you probably don’t want to start much before that.

Now, let’s plant watermelon seeds!

  1. Prepare an egg carton or seed tray with potting soil.
  2. Begin by planting watermelon seeds ½-inch deep.
  3. Cover the seeds with soil.
  4. Water thoroughly but do not saturate.
  5. Label the type of watermelon on the seed cell.
  6. Place watermelon seed tray under grow lights or in a sunny spot indoors.
Young watermelon growing in the garden
Young watermelon growing in the garden

Caring for Watermelon Seedlings and Plants

Watermelons don’t require a ton of care, and truthfully, they may actually do better if you ignore them half the time. You definitely don’t want to overwater them!

Here are some tips on caring for your watermelon seedlings:

  • Monitor daily for moisture needs and signs of growth. Resist the urge to overwater once the watermelons sprout.
  • Transplant to a bigger pot if needed. Sometimes watermelon seedlings grow fairly large quickly.
  • Harden off watermelon seedlings before transplanting outside. Start hardening off as you get closer to the threat of frost passing. Just make sure to bring the plants back inside so they survive any frosty or frozen days before then.
  • Think ahead about watermelon plant supports or fences to climb, if possible. Watermelon plants can take over your garden or part of your yard. Give them a trellis or support to climb up for best results.

Starting watermelon indoors gives you a nice head start on the growing season.

Now that you know how to grow watermelons from seed, you have no reason not to try it this year!

Find some watermelon seeds for sale and plan your planting when the timing matches up in your zone.

Do you have any questions on growing watermelon from seed? How about a tip we haven’t thought of? We love hearing from you in our comments!

Happy Gardening!

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