When and How to Direct Sow Watermelon Seeds in the Garden
If you want to enjoy sweet and juicy melons this year, you can direct sow watermelon seeds to get started. Farmer Briana Yablonski shares when and how to plant these seeds in your garden.
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When hot summer days arrive, few garden-grown goodies taste as good as a watermelon. Sowing these seeds at the right time allows the melons to grow throughout late spring and summer, ripening just as the heat becomes unbearable.
You can transplant watermelons to get a jump start on the growing season, but sowing the seeds straight into your garden also works well. I’ll share when and how to direct sow watermelon seeds so you can enjoy sweet and juicy melons a few months later.
Why Direct Sow Watermelon Seeds?
Planting watermelon seeds directly in your garden allows you to skip the work and tools involved in starting seeds indoors and transplanting. There’s no need to gather pots and grow lights, and you don’t have to worry about tiny containers of soil drying out while you travel for a few days.
When you direct sow watermelon seeds, you can also skip worrying about the plants becoming stressed during the transplanting process. Watermelons tend to be especially susceptible to transplant shock, and direct sowing lets you avoid this.
When to Direct Sow Watermelon Seeds
If you decide to direct sow watermelon seeds, waiting until the right time is one of the key considerations.
Watermelons are warm-weather crops with seeds that require warm soil to germinate properly, so planting them too early can lead to poor germination and/or stressed plants. It’s easy to think that the first few warm spring days mean it’s time to seed, but take a step back and look at current and historical data to make sure you’re not seeding too soon.
First, check the soil temperature. Watermelon seeds germinate best when the soil temperature is between 80 and 90°F (27-32°C), but you can sow them once the temperature reaches 70°F (21°C). If you’re not sure about the soil temperature, you can use your last spring frost date as a guide.
All gardeners should wait until after their last frost to plant seeds, but the exact planting time depends on your location and the air temperature. Waiting two to three weeks after your last frost is generally a good rule of thumb, as long as the nighttime temperatures remain above 50°F (10°C) during sowing time.
You can also direct sow watermelon seeds later in the summer, as long as they have sufficient time to mature. The exact days to maturity depend on the variety, but most types of watermelon are ready to harvest 70 to 90 days after sowing. Therefore, get your seeds in the ground no later than three months before your average first fall frost.
How to Direct Sow Watermelon Seeds
Properly sowing watermelon seeds involves selecting a suitable location, planting them at the correct depth, and providing sufficient spacing.
Choose a Suitable Location
All types of watermelon grow best in well-draining soil and full sun. Choose a location that receives at least eight hours of sun each day, preferably with bright morning light.
Since melon vines sprawl across the ground, you should also think about weed management before you sow the seeds. Spreading mulch on the ground around your melons will limit weed growth and also keep the melons off the soil.
Plant at the Right Depth
Watermelon seeds are bigger than many other fruit and vegetable seeds, so you can plant them deeper than other seeds. Sowing the seeds one-half-inch to one-inch under the soil surface will trap an adequate amount of moisture and allow the seeds to germinate.
Planting too shallowly may cause the seeds to dry out before germination, and planting too deeply may cause the seedlings to rot before they break through the soil surface.
Provide Enough Space
Watermelon plants produce sprawling vines that can quickly carpet your entire garden. Therefore, it’s important to provide them with enough space at planting time.
Sow a group of three watermelon seeds every two to three feet, with six to eight feet between rows. If you’re growing in a small garden or raised bed, plant your watermelon seeds at least three feet away from any other plants.
You may be able to get away with close spacing if you plan to trellis your melons. If you’re growing multiple watermelon plants on a single trellis, you should still space the plants two to three feet apart.
Thin Seedlings as Necessary
As long as the seeds stay warm and moist, they should germinate within one to two weeks. Viable seeds and favorable conditions may result in three seedlings per sowing location. Since these plants can become crowded, thin them to one plant.
Watermelon roots are sensitive to disturbance, so I recommend avoiding pulling them from the ground. Instead, you can use a knife or a pair of scissors to cut the stems at ground level.
Tips for Direct Sowing Watermelon Seeds
Now that you understand the basics of direct sowing watermelon seeds, here are some tips to make the process more fun and exciting.
Hill the Soil to Speed Germination
You may have heard of planting watermelons in small hills of soil. What’s up with that? Well, it turns out that there is some logic behind this method.
Hilling the soil allows it to warm up faster and drain well. That means the seeds will germinate faster, and the roots won’t have to sit in wet soil.
While hilling can prove beneficial, you don’t have to mound the soil before planting. Sowing your seeds in a raised bed or straight into the garden can also lead to healthy and happy plants.
Plant More Than Once
Although watermelon plants produce multiple fruits, they all ripen around the same time. Planting multiple rounds of watermelon seeds a few weeks apart will allow you to enjoy the sweet melons throughout the summer.
If you plan to succession plant, keep the growing season in mind and ensure the melons will have time to mature. Growers with a short frost-free period may only be able to plant melons once.
