Your Cool Home is supported by its readers. Please assume all links are affiliate links. If you purchase something from one of our links, we make a small commission from Amazon. Thank you!
You can plant watermelon plants in the ground once the soil has warmed up and all danger of frost has passed.
This usually means waiting until nighttime temperatures stay consistently above 50°F, which for most gardeners is late spring to early summer.
Watermelon plants are heat lovers, so they won’t do much growing if you rush them into cold soil.
If you get this timing right, planting watermelon plants in the ground becomes a straightforward process.
In this post, we’ll walk through how to plant watermelon plants in the ground step by step, including soil prep, spacing, and the aftercare that keeps your vines thriving.
Let’s jump in.
When to Plant Watermelon Plants in the Ground
Timing is everything when you plant watermelon plants in the ground, so let’s break down what to look for.
1. Wait for Warm Soil
Watermelon seeds and transplants both need soil that’s at least 65°F, though 70°F or higher is even better.
If the ground is too cold, your watermelon plants will sit there sulking instead of growing.
A cheap soil thermometer takes the guesswork out of this, and it’s worth grabbing one before you plant watermelon plants in the ground.
2. Watch the Frost Dates
Watermelon plants have zero tolerance for frost, so plant them at least two weeks after your last expected frost date.
In cooler climates, you can start seeds indoors three to four weeks earlier and then transplant them once the weather settles.
This gives you a head start without risking cold damage when you plant watermelon plants in the ground.
3. Check the Forecast, Not Just the Calendar
A warm week in April can trick you into planting too early, only for a cold snap to roll through in May.
Look at the ten-day forecast before you plant watermelon plants in the ground and make sure no chilly nights are lurking.
How to Plant Watermelon Plants in the Ground
Once the timing is right, here’s how to plant watermelon plants in the ground so they get off to a strong start.
1. Pick the Right Spot
Watermelon plants need full sun, meaning at least eight hours of direct sunlight daily.
The more sun they get, the sweeter your melons will be, so don’t skimp on this step when you plant watermelon plants in the ground.
2. Prepare the Soil
Watermelon plants love loose, well-draining soil rich in organic matter.
Mix in compost or aged manure a few weeks before planting, and make sure the pH sits between 6.0 and 6.8.
If your soil is heavy clay, consider planting in raised mounds or hills, which also helps warm the soil faster when you plant watermelon plants in the ground.
3. Space Them Properly
Watermelon vines sprawl, so give them room to roam.
Space plants about three to five feet apart in rows that are six to eight feet apart.
If you’re growing smaller bush varieties, you can tighten that spacing a bit when you plant watermelon plants in the ground.
4. Plant at the Right Depth
If you’re transplanting seedlings, set them in the ground at the same depth they were growing in their pot.
Burying the stem too deep can cause rot, so keep the crown level with the soil surface when you plant watermelon plants in the ground.
For direct sowing, plant seeds about one inch deep, with three to four seeds per hill, then thin to the strongest one or two.
5. Water Gently After Planting
Give your watermelon plants a good, slow soak right after planting to settle the soil around the roots.
This first watering helps them recover from the shock of moving and encourages roots to spread.
Caring for Watermelon Plants After Planting Them in the Ground
Getting them in the ground is only half the battle, so here’s how to keep your watermelon plants happy.
1. Water Deeply but Not Too Often
Watermelon plants have deep roots and prefer a thorough soak once or twice a week over light daily sprinkles.
Aim for about an inch of water weekly, and try to water at the base rather than the leaves to prevent disease.
2. Feed Them Wisely
Once vines start running, give your watermelon plants a balanced fertilizer or side-dress with compost.
Too much nitrogen leads to leafy vines with few fruits, so don’t overdo it.
3. Mulch and Weed
A layer of mulch keeps moisture in and weeds out, which matters a lot when you plant watermelon plants in the ground.
Weeds compete for nutrients, so pull them early and often.
4. Watch for Pests and Disease
Aphids, squash bugs, and powdery mildew are common headaches for watermelon plants.
Check your vines regularly and act fast if you spot trouble, because healthy plants produce sweeter fruit.
So, How Do You Plant Watermelon Plants in the Ground?
You plant watermelon plants in the ground once the soil is warm, the frost threat is gone, and you’ve picked a sunny spot with rich, well-draining soil.
Set them at the right depth, space them generously, water them in, and keep up with care as they grow.
Do all that, and you’ll be rewarded with vines full of juicy, homegrown watermelon by late summer.
Happy planting.