The Truth on Wives’ Tales, Myths, and Traditions on Choosing Ripe Watermelon


            Earlier this month, I published an article on harvesting watermelons.  I took you through the paces of choosing the perfect watermelon through various outward indications. These signs I took for granted, assuming them to be tried and true.

The more I thought about it, however, the more I suspected some of the indications as mere myths, and not facts.  Today I want to separate fact from fallacy.  With 6 watermelons, we will explore six traditional indications for judging ripeness.  Notably, the indications for the best watermelons are:

  1. Dark, dull watermelon
  2. Yellow bottom, instead of under ripe white one
  3. Soft means overripe
  4. Deep pitch = best watermelon
  5. Straw will spin when placed on ripe watermelon
  6. Heavier is always better

The true determination of ripeness will be proven with refractometer. This instrument measures the percentage of sugar content in the melons. Stacy Lyn will then taste the melon which is objective, but she has a pretty good palate. This is really the true measure we are after anyway.
Stacy Lyn and I used our senses to determine appearance, bottom color, firmness, and pitch.  We could have used scientific instruments for each test, but if the results are too close for us to distinguish by our senses, then they are no good to us in the field.  We found that we needed the other melons to determine qualities such as pitch and color; an instrument would not be able to give results of relativity.

The straw test I found quite interesting.  Many watermelon aficionados continue to trust the unique method after many decades of use.  A November 1945 issue of Popular Science describes the method of the straw test.  A picker places “a broom straw horizontally across a watermelon.  If the melon is ripe, the straw will turn to a 45-degree angle; if it is green, it will not move.”  The subsequent January issue proposes the straw test works by the electrical force present in the watermelons.

For the straw test, we obtained 3 broom straws from 2 different brooms, and a “green” Johnson grass twig harvested just before the test.  In a room with minimal wind, we tested the theory by placing the straw in the center, perpendicular to the stem/bloom-end orientation.  Each watermelon was tested 8 times, with each twig being tested, once on each side of the melon.

Nearly every farmer you talk to will tell you to “pick a heavy one” when choosing watermelons.  I interpret “heavy” as heavy for it’s size, and not heavy compared to the rest, or else I will almost always come home with the largest watermelon!  To get this, I went further than the average picker and measured the melons by the weight as compared to volume.  I found the weight on a kitchen scale and found the volume by dipping the melons in a 5-gallon bucket and finding how much water they displaced.

Watch the results or read the results below. Very interesting outcome.


 We determined the ripeness by the aid of a refractometer and our taste buds. A refractometer uses the fact that water refracts (bends) light differently with different concentrations of sugar to determine the percent sugar, in degrees Brix, in the fruit juice.

When it comes down to it, however, a lot can be said for taste.  Tasting allows us to gather and compare all the aspects of a good watermelon; sweetness, acid, texture, and moisture.  The percent sugar and taste correlated well in the results.

The graph tells it all.

Watermelon Chart
The appearance and color generally proved true to traditional standards, but a couple watermelons, like #3, broke the rule and still tasted decent.

The soft melon, #4, tasted the best of the 6, but possessed an old, grainy texture.

The “thump test,” or pitch, generally tried true.

I saw no pattern in the straw test. Stacy Lyn wanted this to work and it may some of the time, but in this experiment it was not conclusive.

There was somewhat of a pattern in “heaviness,” or density, but watermelons like the heavy but inferior #2 (lacked acid), and the light but delightful #4 challenged the pattern.

I believe, after looking at the results, pitch matters the most when picking the best watermelon.  All deep sounding watermelons tasted great.  Further, the pitch correlated with appearance, giving no need to even look at the melons.  You might end up with an overripe melon, however, so if soft, pass it up. I, nonetheless, believe the pitch test to be your best bet and have proven predictable enough for me to convert, and from now on, be a “thumper.”

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