Can Watermelons Survive Frost?

When is the best time to plant and pick watermelons?

ripe watermelons growing outside in cluster of vines

Treehugger / Randi Rhoades

No, watermelons cannot survive frost. Freezing temperatures will cause the fruit to wither and die on the vine. A watermelon covered in frost, even for a short period of time, will turn mushy and inedible. These trailing, flowering plants thrive in the heat, so exposure to snow, frost, or other wintery elements will wreak havoc on a crop.

The growth cycle of a watermelon is about three months from seed to harvest. The fruit needs warm temperatures (ideally between 69 and 84 degrees Fahrenheit), lots of direct sunlight, sufficient water, and nutrient-rich soil to thrive and grow sweeter. Most commercial growers in the United States are located in warmer regions like the South and parts of the West, though the fruit can also be grown in home gardens in colder areas during the summer months.

If planting watermelon in cooler regions, it's best to plant the seeds in the spring, at least three weeks after the last frost. This will ensure a warm growing season and a successful crop. If time is of the essence, some home gardeners and farmers often utilize indoor greenhouses to jump start the process. Seeds grown in containers, in the safety and warmth of the indoors, can be transferred outdoors once they are established seedlings.

The 4 Most Common Watermelon Varieties

There are dozens of watermelon varieties, but only four are grown regularly for grocery stores and supermarkets:

  • Seedless - newer variety, sweet, and free from seeds.
  • Orange flesh - round or oblong, orange-yellow on the inside rather than the typical red color associated with the fruit.
  • Picnic - larger, oblong shape, with black seeds.
  • Icebox varieties - also called sugar babies, smaller in size, look like cannon balls.

When to Plant Watermelon

close view of watermelon starter plants in seed trays

Treehugger / Randi Rhoades

Watermelons are fast-growing and easy to maintain, provided the plants have the space they need. One seedling will sprout multiple trailing vines, which stretch and sprawl several feet in length. Giving them adequate room to grow in the garden also ensures they won't overtake nearby plants and flower beds.

Planting times vary depending on the region where watermelons are grown. Unless they’re grown indoors, field-raised watermelons are typically planted anywhere from May to July. By waiting until late spring or early summer, the crops will avoid any unexpected cold blasts that may destroy the plant. In any case, temperatures should be above 70 degrees Fahrenheit during the day and no lower than 50 degrees at night.

early stages of growing watermelon outside with vines trailing on log
A few weeks after the watermelon sends out its runners, it produces male and female flowers.

Treehugger / Randi Rhoades

The plants do best in sandy soil that is rich in acid and nutrients. They don't grow well with soggy roots, so be sure that the area offers good water drainage. Manure or high-quality compost can be added to the soil to facilitate growth.

When spacing the plants, allow at least 2 feet between seedlings for their low-growing vines. As the watermelon seedling grows, the vines will begin to spread out and sprout yellow flowers. Once the flowers drop, tiny green melons will take their place and begin to grow into mature fruit. The number of vines on a plant represents the number of watermelons it will produce, and each vine typically produces between two and four watermelons.

When to Pick Watermelon

two hands grab watermelon nestled in vines ready to be picked

Treehugger / Randi Rhoades

The longer the watermelon grows in warm temperatures, the sweeter it will be. Since the plants like long, hot, growing seasons, it may take anywhere from one to three months before the fruit is fully ripened, depending on the climate. If there's any expectation of an early frost or freeze, it's best to pick the fruit right away. Even the slightest exposure to colder temperatures will result in ruined fruit.

In general, the fruit's color can be one of the best indications of its ripeness. A watermelon with a smooth rind and deep coloring is ready to be picked. If it's still in the field, it's helpful to inspect the area around the stem, which turns brown as an indication of readiness. The spot where the fruit rested on the ground as it grew should have a lighter yellowish color. Weight and sound also matter when picking fruit. A heavy watermelon is a good sign, as is a hollow sound when you tap on the fruit.

fresh-cut slices of watermelon on a plate outside on picnic table
Pictured is the Crimson Sweet variety, known for its deep red color and, natch, sweet taste.

Treehugger / Randi Rhoades

View Article Sources
  1. Noh, Jaejong, et al. "Effect Of Heat Treatment Around The Fruit Set Region On Growth And Yield Of Watermelon [Citrullus Lanatus (Thunb.) Matsum. And Nakai]." Physiology and Molecular Biology of Plants, vol. 19, no. 4, 2013, pp. 509-514, doi:10.1007/s12298-013-0174-6

  2. Akintoye, H. A., et al. "Yield and Fruit Quality of Watermelon in Response to Plant Population." International Journal of Vegetable Science, vol. 15, no. 4, 2009, pp. 369-38, doi:10.1080/19315260903012110