Watermelon buying guide: spotting ripe, sweet or spoiled fruit and the yellow variety

Experts advise several visual and tactile cues to choose a ripe watermelon. A pronounced contrast between dark‑green and light‑green stripes, a creamy yellow spot where the fruit rested on the ground, a dry stem, and a deep resonant thump when tapped all indicate ripeness and sweetness. Heavier fruit of similar size is also likely to be juicier.

Signs that a watermelon has gone bad include foam on the rind or flesh, soft or cracked skin, off‑putting sour or fermented odors, and discoloration such as dark spots or mold. When any of these are observed, the fruit should be discarded to avoid health risks.

A less common variety, the yellow watermelon (Citrullus lanatus), originates from a Japanese botanical graft and is now cultivated in parts of Italy such as Basilicata, Lazio and Sicily. It looks like a regular watermelon on the outside but reveals bright yellow flesh that is sweeter with tropical notes. It remains a niche product, typically found at local markets rather than large supermarkets.