How To Grow Watermelon For Tasty Fruit All Summer Long

Learn how to grow delicious watermelon this summer!

Small green watermelon growing in a garden
(Image credit: Allchonok / Getty Images)
Quick Facts

Botanical name: Citrullus lanatus

Height: ground-level vining plant

Spread: ground-level vining plant

Sun exposure: full direct sun

Soil requirements: well-draining

Hardiness zones: annual

When to plant: start the seeds indoors 4 weeks before the last spring frost

As summer grows closer, you may be wondering how to grow watermelon. The juicy fruit of these iconic melons epitomize summer sun and fun. Watermelon plants require a lot of space and sun, a sunny site and well-draining soil. You can grow watermelon more quickly by starting the seeds indoors before the first spring frost.

Watermelon Plant Care

Watermelon plant care is easy. Here are the basics.

Man admires small watermelon growing from overhead trellis

(Image credit: owngarden / Getty Images)

Light

Watermelons need between 8 and 10 hours a day of sunlight to bring fruit to maturity.

Water

Given how juicy the fruit are, it will come as no surprise that watermelons need lots of water. You need to keep the soil moist to a depth of 6 inches (cm). The ideal way to water is drip irrigation.

Temperature & Humidity

Watermelon prefer warm air and warm soil. Excess humidity can cause mildew and other fungal issues. The soil should be warm – some 65 degrees F – before planting.

Soil

Well-draining soil is essential when planting watermelons. Neither very acidic nor very alkaline soils work well for growing this fruit. Keep the soil pH at between 6.0 and 7.0.

Fertilizer

It’s best to do a soil test to see which, if any, nutrients are lacking. Otherwise, apply a balanced product. Blending in organic compost will improve the soil.

Problems, Pests & Diseases

Aphids and cucumber beetles can attack watermelon plants, with late-planted crops being the most affected. Powdery mildew and wilt are the diseases to look out for. Deer are attracted to the foliage and can ruin a crop.

How to Plant Watermelon Seeds

Closeup of woman picking watermelon amongst vines

(Image credit: Cavan Images / Getty Images)

You can start watermelon seeds indoors a month or so before the last spring frost. Alternatively, plant the seed outside in worked beds in hills about 6 feet (2 m) apart, with 9 feet (3 m) between rows. Yes, watermelon vines need elbow room. You can help the soil warm up by placing black plastic over the area before planting.

Thin seedlings when they are established, leaving three healthy shoots per hill. to the best three plants per hill. If you want to plant seedless melons, intermix a row of seeded melon plants for pollination.

Harvesting

Different varieties of melons have different times to maturity. Generally, they are ready for harvest between 70 and 90 days after planting, or 35 to 45 days after flowering. Look for a curly tendril at the stem – when it is dry, the fruit is ripe. You can also tell by tapping the fruit. When they are ripe, the noise sounds hollow.

Storing

Watermelon fruit can be stored for a few weeks at 45 degrees F.

Triangular slices of watermelon on a cutting board next to a whole watermelon

(Image credit: HUIZENG HU / Getty Images)

Varieties

There are many different varieties of watermelon seeds on the market. If you want the biggest fruit, pick Mardi Gras, Royal Majesty, or AU-Producer. For early harvest, consider Sugar Baby, Yellow Baby, or Golden Crown.

Frequently Asked Questions

How long does it take to grow a watermelon?

From starting seeds in February or March to harvest will be about 80 – 90 days.

Do watermelons need full sun?

Yes, watermelon require 8 – 10 hours of sunshine a day.

Teo Spengler
Writer

Teo Spengler has been gardening for 30 years. She is a docent at the San Francisco Botanical Garden. Her passion is trees, 250 of which she has planted on her land in France.