Growing your own watermelons from seed is actually pretty straightforward! The big secret to success is getting an early start indoors. These sun-loving fruits need a long runway to go from a tiny seed to a juicy, ripe melon. If you’re hoping for a big harvest, you’ll want to get moving in early spring.
Pre-Sprouting
You don’t *have* to pre-sprout watermelon seeds, but it’s a great little trick to speed things up. In the fall, every day of sunshine counts—once that first frost hits, the vines are toast, and watermelons don’t really ripen much once they’re off the plant.
Pre-sprouting also saves you some shelf space because you only pot up the seeds that actually show a little root tail. No more waiting around for “dud” seeds! Usually, watermelons sprout within a week, though some stubborn varieties might take up to two.
To do this, just tuck your seeds between two damp paper towels and pop them into an airtight container, like a Tupperware or a Ziploc bag. Just be sure to open it up every now and then to let in some fresh air so things don’t get moldy.
Sowing the Seeds
You’ll want to have your watermelon seeds sown by early April at the latest. Use a nutrient-rich veggie potting mix and fill up some small starter pots. Like their cousins in the squash family, watermelons are “homebodies” when it comes to their roots—they hate being disturbed. Skip the open seed flats where you have to pull them apart later; individual pots are the way to go.
Place your pre-sprouted seeds in the pots and cover them with about half an inch of soil. Keep them somewhere warm until those first seed leaves (cotyledons) pop up. Once they’re up, move them to a slightly cooler spot (around 60°F or 15°C) where they can get at least 12 hours of bright light.
Planting Out
Watermelons are all about that “warm and dry” life. They have zero tolerance for frost, so don’t even think about moving them outside until mid-May. If you’re lucky enough to be growing watermelons in a greenhouse, you can usually get a head start and plant them out around the second week of May.
The good news? Watermelons aren’t too picky. Before you plant, prep the soil with some well-aged manure or compost. I also like to mix in some horn meal or a similar slow-release organic fertilizer. After that, just give them a boost of liquid fertilizer every two to three weeks, and you’ll be on your way to a delicious summer treat!
