June 27, 2012

Watermelon Guessing Game: How to Tell if a Watermelon is Ripe

There's nothing worse than watching a watermelon grow to size for weeks on the vine and then cracking it open only to find it's not quite edible. Last year I played and lost the watermelon harvest guessing game so many times I almost decided not to grow them this year, but I didn't want to give up after just one season. I put them in my summer garden again, and I'm glad I did!

New Queen yellow watermelon

Watermelons are notoriously difficult to harvest, and sit at peak ripeness for only a day or two. They do not continue to ripen once cut from the vine, so the ideal harvest window is very small. Researching this online, I've found lists of more than ten factors to consider when trying to figure out whether a watermelon is ready. Some advice is ridiculously unclear, as in the following from gardenweb: "Thump it. If the watermelon sounds hollow (if you hear a dull thump/thud), the melon is usually ripe. The unripe melon will have a tighter, metallic ringing or hollow sound." Huh?

Looking ready to pick, but is it? (No!)

Having learned through trial and error last summer, I now look at just three factors as I attempt to avoid splitting open a pale, under-ripe melon:
  • weight
  • tendril
  • leaf

First, I look for a watermelon that is heavy for its size. Watermelons are made mostly of water (duh!) and water is heavy. I evaluated this watermelon for weight before cutting it, and then used the scale to find out it weighed 5.5 pounds, which is in the correct range for this variety.

This one weighed in at about 5 1/2 pounds

The second factor I take into account is the status of the curly tendril closest to the stem of the developing fruit. In the first picture below, taken two weeks ago, the tendril is still green, a sign the melon isn't ripe. In the second picture, the dry tendril is an indication the melon is ripe.

Green, flexible tendril indicates an unripe melon

Brown, dry tendril indicates a ripe melon

The last thing I look at is the tiny leaf closest to the stem of the developing melon, called a "spoon" leaf for its shape. A green leaf is a sign the watermelon is still developing; a dry leaf is an indication the melon is ripe. Sometimes you might not find a leaf at all, which probably means it has dried and fallen off the stem.

"Spoon leaf" is still green and attached to the plant

There are three factors I don't pay attention to in this guessing game. One is sound, something experienced farmers supposedly use to determine ripeness: if the watermelon makes a tinny, metallic sound upon tapping it in the morning, it's not ready, but if it makes a dull, thumping sound, it's ready. I tried this multiple times last summer and when I thought I could tell the difference, I was wrong.

I also found size not to be a trustworthy indicator of harvest readiness. Last year we grew Sugar Baby melons and those were supposed to be small, like these New Queens. One grew to almost twice the expected size, so I thought for sure it was ripe--nope.

Finally, I disregard the color of the underside of the melon. Everything I read says a ripe watermelon has a yellow underside, and that an unripe one has a pale green or white underside. My experience has been almost the opposite. The first picture below shows my watermelon two weeks ago with a prominently yellow underside. The second picture was taken at harvest, by which time the color had paled.

Two weeks ago, yellow underside indicates ripening

At harvest, melon has a pale yellow underside

I'm happy to report that I did in fact win the guessing game with the watermelon pictured in this post. I cut it from the vine (no pulling, the way you harvest other types of melons), split it open and was delighted at the bright yellow color, rich flavor, and crisp texture. I probably could have cut it a day or two earlier, but it's hard to tell. It tasted great to me.

Half a New Queen watermelon

Bowl of sweet melon slices

I leave a little extra on the rind for the chickens

Score so far: unripe/overripe melons: 0, me: 1. Have you ever tried growing watermelons in your garden? Got any secrets for harvesting at peak flavor?


  1. I would have expected such a melon to have pink inside. Hmm. Does this taste the same or more like a cantaloupe?

    1. Funny, huh? I didn't know about yellow watermelons until we started our CSA box. It tastes exactly like a pink watermelon. You wouldn't know the difference if you were eating it with your eyes shut.

  2. Hi, my name is Nathan. I was wondering if I can use a few of your pictures for a book I am writing on community gardening. They are exactly what I am looking for. I will credit it to whomever, however you like. Please email me back at nthnrdr (at) dordt (dot) edu. Thanks!

  3. Annette in MississippiJune 24, 2015 at 10:27 AM

    You've experienced the same trouble that I came here hoping to find some insight on. I breed watermelons as an amateur hobbiest. This year I am growing some melons together. One is an old time-y hybrid grown from diverse watermelon seeds sewn together the way hybrids have always been created by planting different types together to create new watermelon cultivars. The other melon in the hill is basically the result of a Sugar Baby melon which came up volunteer in the last of its season and probably wasn't even hybridized with any other melon from another vine because all the other vines were dead by that time. However, it might have been pollinated with another melon. I just don't know. I came here to find insight because almost everything I know about watermelon growing came from the internet, and I almost know enough to write a watermelon book for beginners. Nevertheless, there's still a lot I don't know.

    Now this year I am using those seeds previously described, and my melon patch looks beautiful. The melons in the hill look a lot like Sugar Babies, and are developing round shapes with the obvious dark blue green color that Sugar Babies have as they mature. Every one of them looks like that. Therefore I know that the Sugar Baby pollinated every melon in the group. I just harvested my first melon this morning and it is being refrigerated as I write. I have no idea what it's like inside yet. I'll know when I get home.

    I agree with everything you said. I find the thumping to be more useless than helpful. Also my watermelons started with bright orange bottoms and not white or off white at all. If anything they've faded from bright orange to orange with greenish blurs on the edges. To that I say just look for any color change in the melon with emphasis on the word, "any". The tendril faded from bright green to soft green. I also saw the almost completely dead spoon leaf on the melon yesterday. It was gone today. I didn't know whether to harvest today or tomorrow. I didn't have anything to weigh with, but it felt as heavy as a ripe melon that size should in my opinion.

    The main two reasons I decided to harvest was because I read yesterday that firmness should be taken into account. I compared all of the melons and found this one to be definitely firm all over. It also had that dead spoon leaf, and I didn't know if the curl would ever die completely, but I know that I was getting close to the peak of perfection. My gut reaction tells me that I should have waited until tomorrow. I 'll know this afternoon.