Knowing when melons are ripe can be a challenge. There is no hard-and-fast rule. Each melon variety is a little different and keeping a watchful eye is important.
Muskmelons don't get any sweeter after harvest, they just get softer, so it's important to pick them at their peak. Muskmelons "slip" from the vine when they're ripe, which means the vine naturally detaches from the fruit. We advise picking about 2 days before this, at "half-slip" stage, to ensure the fruit won't be overripe. To harvest at half-slip, apply gentle pressure at the point where the vine attaches. The vine will detach from the melon with a light tug. Another clue to ripeness is the appearance of the melon beneath the netting on the rind. The skin color will turn from green to paler green to yellow, indicating the fruit is probably ripe.
Some melon types, like honeydews, charantais and crenshaws, are overripe if grown to half-slip. These types need to be cut from the vine with a scissors or shears. Their rind color often changes to gold or white when ripe and the leaf nearest the fruit fades from green to pale yellow. Also, the smooth-skinned types have small hairs that fall off when ripe. The melons will be slightly slippery and smooth. One other indication of ripeness is smell. You should be able to smell sweet, fruity fragrance on the end of the fruit where the flower was originally located.
When it comes to watermelons, the scientific approach is to count off 35 days from the day the female flowers fully open. That's when the fruit will be ripe. Since most of us aren't that observant, some other clues are:
The more you grow melons, the better you will be at knowing when to pick. Keep notes in your garden planner that you can refer to year after year.
Another melon-growing tip - avoid garden overwatering about 2 weeks before the fruits are ready to pick. They will be sweeter tasting!