Watermelon Characteristics

The watermelon plant (Citrullus vulgaris) originally comes from Africa, but today you can grow it anywhere in U.S. Department of Agriculture plant hardiness zones 3 through 11. Its juicy, sweet fruit often signifies the arrival of summer in many people's minds. If you're planning to grow watermelon in your garden, knowing the plant's growing characteristics and the backyard conditions it needs to thrive can ensure healthy watermelon plants and a big, bountiful harvest.

Watermelon Growth

In general, most watermelon plants grow to a height of approximately 24 inches, and sprawl approximately 3 to 20 feet wide. The vine produces coarse, medium-green leaves, while the fruit can weigh anywhere from 10 to 20 pounds with marbled, solid or striped skin.

Planting Time

Watermelon is the quintessential warmth-loving plant and does not tolerate cool temperatures. You can start planting watermelons once the soil temperature is a minimum of 60 degrees Fahrenheit, although optimal germination takes place when the soil heats up to approximately 95 degrees F.

Soil Characteristics

Watermelon plants grow best in soil that drains well and is rich in organic matter and nutrients. To improve soil structure, mix 3 to 4 inches of organic compost into the top 6 to 8 inches of soil before planting your watermelons. Additionally, fertilize the area at a rate of 15 pounds of 5-10-10 fertilizer for every 500 square feet of gardening space. This helps create the soil characteristics that watermelons need.


Plant the watermelon seeds directly in the prepared soil once you have finished with the necessary soil amendments. Bury each seed an inch deep. Space each plant apart by approximately 10 feet. If you're planting more than one row of watermelons, space each row apart by approximately 18 feet.

Caring for Watermelons

Water the planting site twice daily, or as necessary to keep the top 2 inches of soil consistently moist. Continue this until the watermelons germinate, which generally takes five to 10 days. Once the plants are established, water once daily, using enough irrigation to moisten the soil to a depth of 6 inches. Avoid changing this watering routine. Irregular irrigation promotes drought stress, which in turn can cause poor fruiting or cracked fruit in this water-loving plant. Maintain a weed-free area around your watermelons by hand-pulling weeds on an as-needed basis -- cultivation with a hoe or similar tool can disturb this plant's shallow roots. Fertilize the watermelons a second time when the first fruits start to appear, applying 1/2 pound of 33-0-0 fertilize for every 50 feet of watermelon row.


Depending on the specific watermelon variety, the fruit is ready to harvest anywhere from 70 to 85 days after planting. A watermelon is harvest-ready when the underside of the fruit turns yellow and when the stem of the fruit turns brown.