From the exterior, the fruits look no different from the red types: They are light green with dark green stripes, and the plants have the same lobed leaves. Some yellow watermelon plants produce large fruits, between 20 and 40 pounds, ideal for sharing at a picnic or party, while others produce small, 6-pound fruits. The plants are vigorous and grow best in areas with long, hot summers. Grow a mix of yellow and red watermelon vines in the same garden, and dazzle your friends with a yellow and red medley of fruit at your next Labor Day celebration. Watermelons should be planted by seed in spring garden when the soil has warmed. They take anywhere from 70 to 100 days to grow fruit ready for harvest, depending on variety. Starting yellow watermelon seeds indoors is not recommended. Wait until soil temperatures are at least 70 degrees Fahrenheit planting seeds outdoors. It’s important that the soil be warm—not just the air temperatures. Delay planting until about two weeks after the last frost of the season. You can also plant in raised beds or cover the soil with plastic to speed up warming. Make a mound of soil 6 to 8 inches high for seed planting. Rows should be at least 4 feet apart; mounds should be 3 feet apart. Plant two or three seeds in the mound, 6 inches apart. After germination occurs in about eight days, remove all but the most vigorous seedling.
Yellow Watermelon Care
Light
Yellow watermelon plants need a full day of sun. Plant them away from buildings or tall plants that cast shade.
Soil
A rich, sandy loam will produce the healthiest yellow watermelon harvest. Add compost or manure to poor soils; in areas with clay soil, use raised beds with amended soil to improve drainage.
Water
Keep soil moist but not soggy until fruits form. After fruits reach softball size, water only when the surface of the soil is dry. Overwatering can cause rapid growth that leads to cracking.
Temperature and Humidity
Yellow watermelons love hot weather, but if an extended hot spell in the triple digits is stressing plants, you can use shade cloth. Hot weather combined with high humidity can make plants susceptible to powdery mildew. Increase spacing to help air circulation and reduce fungal spores.
Fertilizer
Chemical fertilizers aren’t necessary to grow yellow watermelons. The slow, steady stream of nutrients from leaf mold, compost, or manure as a top dressing will increase soil fertility and tilth. Some commercial growers have been known to inject fruits with nitrogen fertilizer or other chemicals to stimulate large growth. Never attempt this with a watermelon you intend to eat.
Varieties of Yellow Watermelon
Several good varieties of yellow watermelon to choose from include:
‘Yellow Doll’ hybrids are common in the trade and produce small 6-pound melons with small seeds in 68 days. ‘Yellow Baby’ hybrid has a thin rind and few seeds in its 9-pound fruits. ‘Lemon Krush’ hybrid is a long-season, large type that is resistant to common fungal disease. ‘Mountain Sweet Yellow’ is an heirloom that produces jumbo fruits in 100 days.
Yellow Watermelon vs. Red Watermelon
The seeds, plants, and fruits of red and yellow watermelon look the same, so it’s important to purchase properly labeled seeds or plants to ensure that you don’t get a red surprise when you slice open your melon. You can save seeds from an organic heirloom like ‘Mountain Sweet Yellow’ and get plants that grow true to type, but you will not get identical offspring by saving seeds from a hybrid such as ‘Yellow Doll.’
Harvesting Yellow Watermelon
You can determine the ripeness of a yellow watermelon by observing small changes in the fruit and the vine. The vine or leaves closest to the fruit may become yellow or brown as growth slows or stops. The rind may change from shiny to dull and rough, and the bottom of the fruit will turn pale or yellowish. A watermelon whose rind has turned mostly yellow is likely overripe and past the point of good eating. Watermelons will generally keep unrefrigerated for about seven days after picking.
Common Pests/Diseases
Check daily for squash bugs and squash vine borers on young plants, and remove egg masses or treat with carbaryl. Fungal diseases are more common in cold or wet weather. Reduce fungal spores by watering plants at soil level rather than overhead.
