1 Answer

This is a difficult thing for the home gardener to determine no matter what melon it is. Even specific types will vary depending on what variety it is. The best way to determine maturity of an entire field is to randomly select melons from across the field and use a hand refractometer to measure the sweetness of the melon. Soluble sugars should be 10% or more near the center of the melon. Since most home gardeners probably aren't going to go so far as to aquire that equipment, here are some tips: 

All "melons" are Cucurbits (Cucurbitaceae). The cucurbit family includes species such as the gourd, watermelons, cantaloupes, squash and pumpkins. 

Melons like cucumbers require ample moisture for the growth and fruit setting. During the fruiting ripening stage, however, too much water will diminish the flavor of the melons. 

1. When harvesting, make sure that the melon is cut from the vine instead of pulled. Pulling creates a cracking wound that pathogens can enter and quickly destroy the quality of the fruit, not to mention ruining the appearance of the fruit. Leave the stems on the melon for as long as possible, and treat for stem end rot after picking.

2. Don't harvest your melons until they are fully ripe. Melons will get softer after they are picked from the vine but they will never get sweeter.

3. Most people tap on the fruit and listen for a dull thump. If you grow many of them, this is an art form.