Lately, every watermelon I bring home form the organic section of the supermarket has not been sweet.  Among the small, seedless varieties, I try to pick the densest. How do I know if it is ripe?  Can I ripen them at home?  Should I keep them in the fridge?

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  • The watermelon and the melon I got today were great. Thanks to all. – papin Jul 15 '10 at 3:05
  • One comment I haven't seen in any of the answers or comments. Seedless watermelons are usually less sweet than watermelons with seeds. Also the center of the watermelon where the seeds normally reside whether seeded or seedless is the sweetest part of the melon. – Escoce Apr 10 '16 at 17:41
  • You should make watermelon rind pickles with all of them, but particularly with the ones that are a bit under-ripe, where you'll get a bit more usable rind for pickling. – Ecnerwal Jul 28 '16 at 3:31
up vote 29 down vote accepted

I don't believe there is a fool-proof way to determine 'ripeness' without taking a slice out of it. The best you can do is look for certain signs:

  • Ripe melons have a hollow sound when you tap or slap the outside
  • Look for the patch where the melon would have been on the ground (called the field spot). If it's a yellow colour its probably ripe, if it's white, it's probably not.
  • It should feel relatively heavy when lifted
  • Weird areas on the skin aren't necessarily bad. insects may have tried to start eating the fruit because it is ripe, but have only marred the surface.

Unfortunately, melons don't continue to ripen once picked, unlike fruits such as apples, bananas etc. which contain ethylene. As a tip don't store melons with these kinds of fruit, they may well go 'soggy'.

Extra: NYtimes video on picking the right watermelon.

  • Thanks for mentioning the storage; I just moved my melons away from the apple-containing fruit bowl! – JustRightMenus Jul 23 '10 at 2:31
  • Thanks @Michael Pryor for the NY Times video link. For the record, this summer I've had nothing but great watermelons. – papin Aug 25 '10 at 2:18

As pulse said, colour is a good indicator and give them a tap and they'll have a nice hollow sound.

The other thing I do is pick them up... I don't know why, but ripe melons tend to feel "heavy" for their size.

  • 10
    +1 for weight comment. Better melons have more water in them, so when choosing between two equally sized melons, pick the heavier one. – Satanicpuppy Jul 14 '10 at 13:48

Shake it. If you hear things moving inside, it's overly ripe.

Press it. If it squeaks a little, it's just OK. If it doesn't, it's either unripe or already wilting.

Knock on it with your finger, like if you'd be knocking on a door. It has to sound just a tiny little bit hollow. Too hollow means overly ripe, not hollow at all means unripe.

For melons other than watermelon, always smell them, they should have a good aroma. Unfortunately this does not usually work for watermelons. The color and weight are usually the best indicators.

I just saw a post on rulesofthumb.com that says:

A watermelon is ripe when you hear "punk" rather than "pank" or "pink" when you tap it with your finger.

  • 4
    What does that even mean? – SAJ14SAJ Aug 30 '13 at 21:15
  • @SAJ14SAJ: That means he's trying to approximate the effect that a complex sound (i.e. composed of a whole bunch of different frequencies) has on your hearing by comparing it to certain vowel sounds (as spelled in English) which are also composed of a lot of different frequencies. The analogy obviously doesn't work for everybody, but short of a spectrum analyzer, can you think of a better way to describe something like that in writing? All that said, my produce guy left me feeling that "punk" was overripe, "pank" was perfect, and ... he didn't really mention "pink" ... great method, isn't it? – Lorel C. Mar 1 '17 at 17:58

I have found that if you look on the bottom of the watermelon, (where it sits on the ground), if it is yellow and the lines are straight and yellowish green then the watermelon is sweet and ripe. If the lines are a light green and wavy then the melon is not sweet or ripe.

  • 1
    Hmm, interesting. The yellow/green thing makes sense to me, but I'm not so clear on the straight vs wavy thing. – Jolenealaska Jun 25 '14 at 0:43

Knock on it lightly. If someone answers, you've got a very special melon! Actually, if it sounds somewhat hollow, it is ripe. As a child we would "plug" the melons by cutting a 2" x 2" trianglebout of it. That's a fool proof way to see if your melon it ripe.

  • 2
    I don't recommend plugging a melon at the supermarket ;) but the knocking is spot on. – Erica May 23 '15 at 11:40

For a sweet melon it normally takes a high sulfer soil for a sweet melon. So you may not find any sweet ones to buy. Thump or knock on the melon it should sound hollow. Melons can not be picked ripe. They bust to easy to ship in totes. So set them in the sun for a few days. Once you wax them to hold in moisture.

  • "They bust to easy to ship in totes"? What are "totes" in this context? – Catija Jun 26 '17 at 21:20

In some stores they have cut melons, check the cut ones out. During sales they will cut them often. Looking at them will help you make your choice.

  • Tote's are big box's 4 foot tall. 4 by 4 foot square. Melons go in them then are trucked to the store. – J Bergen Jun 27 '17 at 17:15

protected by Jolenealaska Jun 25 '17 at 7:41

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