When to Harvest Melons
Harvest smooth-skinned muskmelons—which include honeydew, Crenshaw, and casaba–when they turn cream colored. The blossom end will give slightly when pressed, and the fruit will readily separate from the stem.
Harvest net-skinned cantaloupe when the rind netting changes from gray-green to creamy and the background turns golden. The fruit will have a sweet-musky aroma, and the stem will slip easily from the fruit.
Harvest watermelon when the ground spot–where the melon rests on the ground–turns a creamy yellow and the stem turns brown and begins to curl.
Melons on the same vine typically ripen over a short period of time. As soon as the first melon is ripe, the others will come to harvest within 3 to 4 weeks. After the first melon is harvested, cut back on watering—just enough to keep the vines from wilting; this will concentrate sugars in the fruit.
Here are some general rules for judging the ripeness of a melon:
Smell – the melon will have a strong, “musky” or perfumey aroma at the stem-end of the melon.
Skin — the melon’s skin color will change, from green to yellow or tan for muskmelons and cantaloupes; the underside of a watermelon will change from green to creamy where it touches the ground.
Stem – the stems will separate or slip from the fruit with little effort. First a concentric crack will appear where the stem and the fruit meet then the stem will completely separate (called “full slip”). When signs of slip appear the fruit is ripe and should be picked and eaten within a few days; don’t let the fruit turn soft and mushy.
If you don’t plan to use a harvested melon immediately, leave an inch of stem attached to the fruit to keep it from rotting.
Store whole ripe melons in the refrigerator for up to a week to avoid spoiling; cut melons will keep for up to three days. If you have ripe melons you can’t use immediately, dice or cut the flesh into balls and freeze for slushies or cold soup.
Melons should be kept cold and moist (50°F/10°C and 95 percent relative humidity). Creating cold and moist storage is a challenge: refrigerators provide the cold, but also have dry air. Store cut melon in a perforated plastic bag in a refrigerator. You can purchase perforated plastic bags or make your own by punching 20 holes in a medium-size bag; use a hole punch or sharp object.
Melons are susceptible to chilling injury at temperatures below 50°F; chilling injury symptoms include surface pitting, water loss, yellow, browning of rinds, decreased sweetness, and rapid deterioration.
More tips at How to Grow Melons.