The more genes the fruit has, the more these things are expressed. ... Because it has more genes, a seedless watermelon's sweet flavor is actually expressed more, so the fruit is actually more likely to be more flavorful than a seeded watermelon.

Are watermelon with seeds sweeter than seedless?

Challenges of Seedless Watermelons : Fruit: They're tricky to grow, but the seedless variety is much sweeter and crisper than the seeded melon.

Is watermelon with seeds sweeter?

MYTH: Seeded watermelons are sweeter than seedless.

A seeded watermelon can be sweeter than a seedless one, but it has nothing to do with the seeds. Factors like the melon variety, soil conditions, climate and when it was picked all affect sweetness.