Step 1

When the soil temperature is 70 F. directly sow seeds outdoor. Wait 2 weeks past the last frost date).

Step 2

Plant Watermelons like loamy, well-drained soil.

Step 3

"Amend soil with aged manure or compost before planting. Watermelons are heavy feeders. Spread black plastic over the garden area and secure it with rocks or landscaping pins. To minimize weeds, retain moisture and warm up the soil so you can plant watermelon earlier (2 weeks earlier), which allows for a longer growing season."

When to Water

While melon plants are growing, blooming, and setting fruit, they need 1 to 2 inches of water per week. Water at the vine's base in the morning, and try to avoid wetting the leaves and avoid overhead watering. Reduce watering once fruit are growing. Dry weather produces the sweetest melon.

Cold Hardiness

Because watermelons are warm-season crops, they cannot withstand a freeze or even a light frost. An air temperature of 33 degrees Fahrenheit or below kills watermelons. The best time to sow watermelon seeds or set out watermelon transplants is two to three weeks after the last spring frost date.

Enemies

Fungal diseases can multiple rapidly on melon leaves. Alternaria leaf spot, anthracnose, and gummy stem blight produce spots on leaves, while stem blight also forms bleached or tan sections on stems and rot on fruit. Watchout for pests. Melon aphids, for example, can quickly colonize a vine, so inspect leaf undersides daily. If you spot aphids, treat them with insecticidal soap. Spotted and striped cucumber beetles can attack vines, transmitting bacterial wilt disease, which causes vines to collapse without chance of recovery.

Soil Type

Spread 2 inches of compost or manure over the garden area. Till the soil to a depth of 8 inches. Fertile, deep soils encourage rapid, consistent growth so watermelons set fruit before cold weather arrives.

Plant Height

Watermelons can reach a height of 1 to 2 feet but they require a lot of vertical space (at least 6x6 feet).Take that into consideration when planning your garden. Make sure there is enough distance between your tall vegetables and short vegetables. That way both will get enough sun light.

Harvest

To know if the watermelon is ripe, simply thump it. If the watermelon sounds hollow, it's ripe. Also look at the color on the bottom. If it has a white bottom, it's not ready. Only pick one with a cream or yellow bottom. Watermelons don’t sweeten after they are picked, so harvest time is important. They generally ripen over two weeks so keep you eye on them.

Climate Type

Melons need warm temperatures (up to 80 degrees during the day) and a long growing season.

Fertilization

Watermelons are heavy feeders. They would appreciate a good dose of fertilizers especially horse manure.

Tips 1

As fruit is ripening, prevent rotting by gently lifting it and putting some cardboard or straw between the fruit and the soil.

Tip 2

Watermelon vines bear male and female flowers. Male flowers, which appear first, fall off shortly after they open; they are followed by female blossoms about a week later. The female flowers, which have a small swelling at the base of the flower, stay on the vine to bear fruit.

Tip 3

It’s typical for leaves to wilt under midday sun, but they shouldn’t remain wilted into evening. Protect your melons from large critters such as groundhogs.

Sun Light

Watermelons like full sun and do well when they get about 8 hours of sunlight.

Incompatibles

Cucumbers and Potatoes should not be planted next to watermelons.

Companions

The following vegetables will do well when planted next to watermelons: Corn, Nasturtiums, Peas, Radishes, Sunflowers, and Tomatoes. Planting certain vegetables next to each other can deter insects and encourage growth.

Crop Rotation

"Next year, DO NOT plant pumpkins, melons, squash, gourds, and cucumbers in the same location where you planted watermelon this year. Because they are all members of the Cucurbit family. Instead use that spot to plant other vegetables from a different family such as:

• Carrot (Umbelliferae): celery, carrots, parsley
• Legume (Leguminosae): peas, beans, lentils
• Mustard/Brassica (Cruciferae): broccoli, caulifower, kale, cabbage, Brussels sprouts, turnips, radishes.
• Sunflower (Compositae): lettuce, artichokes.
• Allium (Amaryllidaceae) - onions, garlic, leeks, shallots and chives.
• Nightshade (Solanaceae): tomatoes, potatoes, eggplant, peppers
• Goosefoot (Chenopodiaceae): spinach, Swiss chard, beets.

When vegetables such as watermelons are grown in the same garden space year after year, harmful microbes in the soil that are specific to individual plant families can build up. Additionally, there are vegetables which add nitrogen to the soil and other vegetables which take nitrogen from the soil. Rotating your crops can keep your soil balanced, not too rich or too poor in nitrogen."

Growing Watermelon Overview

Watermelons are not hard to grow as long as they get enough sun light and warm temperatures above 70 degrees F. They are members of the Cucurbit family, which also includes pumpkins, other types of melons, squash, gourds, and cucumbers. For more planting information, please visit our Farming Tips homepage.