Germination is the time it takes for a seed to sprout into a seedling and begin the early part of the growing process for the fruit, vegetable or flower. Watermelon, a summer fruit with red or yellow flesh, requires warm, moist soil for successful germination. Various watermelon cultivars have different germination times and gardeners should be aware of these time frames to ensure sweet, juicy, healthy fruits.
Red Watermelon Germination
Red watermelons are most prevalent and take five days for germination when temperatures are in the mid or upper 70s Fahrenheit. Seeds planted in higher temperatures, like the low or mid 80s, make take only four days to sprout into a seedling. Very sweet red watermelons like the Sugar Baby can be planted near the end of spring and can weigh up to 10 lbs. at maturity. Crimson Sweet watermelons, which are twice the size of Sugar Babies (about 25 lbs.), germinate in the middle of the growing season and take 88 days to become an edible fruit.
Yellow Watermelon Germination
The hotter the weather, the sooner a yellow watermelon will germinate. When summer temperatures are between 90 and 95 degrees, yellow watermelon seeds could germinate in as little as three days. The Yellow Baby watermelon, which has bright yellow fruit is an early germination type; the fruit will be ready to harvest in about 75 days. Yellow Doll watermelons can germinate in a short amount of time as well; they are sugary sweet and have very few seeds. Yellow Doll fruits take slightly longer than Yellow Baby watermelons to reach full maturity -- usually around 85 days.
Seedless Watermelon Germination
All seedless watermelons are hybrids and take the longest time to mature. The seeds germinate between seven and 14 days and they must be kept between 75 and 85 degrees. It's also necessary to plant seedless watermelons next to seeded watermelons, as the hybrid varieties need a pollinator. The watermelon flesh varies in color; for instance, the Honey Heart melon has golden yellow fruit, while the Cotton Candy variety has light red flesh that's almost pink. Plant the hybrid watermelon seeds in clay-like or sandy soil for best results.
Conditions for Germination
Watermelon seeds need nutrient-rich soil and lots of water to germinate and thrive, as over 90 percent of the fruit is made of water. Adding mulch will help the soil retain its moisture and reduce weed growth. For a healthy seedling to sprout, watermelon seeds must be planted in temperatures between 70 and 95 degrees. Position the seeds no more than 5 feet away from each other, so the seedlings have room to mature into large fruit. Plant the seed about an inch into the ground.