Harvesting Ripe Watermelons
I received a recent comment from a gardener inquiring about harvesting ripe watermelons from plants that had volunteered in her home garden.
There’s no guarantee that those rouge plants will produce mature fruits but if they do there are a number of techniques that can be employed to ensure that you harvest the mature watermelons at their peak.
See, Hear, and Feel Your Way to Ripe Watermelons
Many gardeners have trouble determining the best time to pick their home grown watermelons, and many shoppers have difficulty selecting a juicy, ripe watermelon at their local grocer or market. It’s always a big disappointment to lug a nice looking melon home only to discover that it’s hollow hearted, mushy, pithy, or just plain tasteless because it was harvested too early or well past its prime.
The problem is compounded by the fact that watermelons, unlike cantaloupes, will not ripen after they are picked from the vine. But there are a few simple tricks that can make harvesting or selecting a sweet, juicy watermelon more of a skill than a hit or miss gamble. The key is to focus your senses and combine sight, sound, and touch to select perfectly ripe watermelons in the garden or at the market.
If you’re growing watermelons in the garden the first signs of maturity will be visual cues. The underside of the fruit where it rests on the ground will turn a golden, straw-yellow color as the melon matures. For another visual sign of a ripening watermelon locate the curly tendril attached to the vine that is closest to the fruit. As the watermelon matures and ripens this tendril will dry out and become brittle.
Foolproof Methods for Harvesting Ripe Watermelons
A more reliable test for watermelon ripeness, and the one that most expert gardeners rely on is the “thump test.” You may have witnessed a stranger at the market tapping on watermelons with their fingertips or rapping against them with their knuckles as they attempted to choose a good, ripe one.
The secret is that thumping a ripe watermelon will produce a rather hollow sound that’s difficult to describe but once you get the feel for it choosing ripe watermelons will become more routine than a matter of luck. The hollow sound can even be felt with your fingertips, almost as if the fruit contained jello in its center.
This technique may require a little practice and some trial and error, but once you get the hang of it your watermelon harvesting will become easier and more rewarding. For practice, experiment with a bin full of watermelons at the grocer until you can easily distinguish the difference in sound made by a ripe melon.
Acquiring the “Touch” for Selecting Good Watermelons
The final method to judge watermelon ripeness in the garden or at the market is a trick that I picked up from Roger Swain, Science Editor of Horticulture magazine, at this past spring’s Pennsylvania Garden Expo. Roger shared a technique for selecting ripe watermelons that relies entirely on touch and could be performed with your eyes closed if you like.
Simply run your fingers around the center of the watermelon, not lengthwise but around the center of the fruit between the stem end and the blossom end of the melon. An immature watermelon will be smooth to the touch, but as the fruits mature they will develop slight ridges that will be very noticeable as you run your fingers across the rind.
Apply these simple harvesting techniques and the chances are that your next watermelon will be sweet, juicy, and delicious whether it’s harvested fresh from the garden or purchased at your local market.
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July 28th, 2006 at 2:14 pm
I was curious about the color. I’ve always tried to pick ones a little yellow. Do the same with pineapples. Checking for ridges is a technique I hadn’t heard of.
August 11th, 2006 at 10:14 am
What makes watermelons rot before they have matured?
August 17th, 2006 at 10:07 pm
Hi Freda, I’m not positive of what type of rot you’re experiencing with your watermelons. Is it occuring when they are just forming or when the watermelons are ripening? If it’s when watermelons are just beginning to grow and the fruits are still small it could be a case of blossom end rot as described at the following link about tomato rot. Blossom end rot affects not only tomatoes but also peppers, eggplants, and watermelons.
August 21st, 2006 at 11:47 pm
I’m growing a volunteer watermelon in my yard in San Diego. Transplanted it from the rose/flower garden to a better spot, and it has grown like crazy. There are two oval-shaped fruits which appeared about 10 days ago and have doubled in size in the last 4 days (about 7 in. long), and there are other small ones. Should I pick off the little ones to help the larger ones continue to grow and ripen before it gets too cool?
August 22nd, 2006 at 10:54 pm
Evelyn, that’s a great idea removing the smaller watermelons will benefit the larger fruits and enable them to mature and ripen faster since the vine will be able to focus all of its energy on the larger melons. Don’t hesitate to thin the small watermelon fruits because they would be unlikely to mature and ripen if left on the plant anyway.
April 17th, 2007 at 7:56 pm
Amazing information!!! Your Internet site is cool.
April 27th, 2007 at 2:24 pm
I was curious about the color. I’ve always tried to pick ones a little yellow. Do the same with pineapples. Checking for ridges is a technique I hadn’t heard of.
I do not know if the color helps, unless the green watermelons sat too long past “ripe” and the bottom is sometimes yellow. Over about a 20 year period while trying to purchase watermelons myself, I conducted informal surveys of other shoppers/grocery workers for a good list of “how to pick” a sweet honeydew melon, watermelon:
Largest melon (if price each), not by weight
No bad odors; possibly sweet smell or no odor at all
Consistent plumpness and shape similar for both halves
Shiny and smooth rind, minimal bruising, patching, or pits Rind/fruit skin exterior scarred in a “zipper” pattern, often referred to as “Bee Stings”
Melons destined for local markets can remain on the vine until the full slip stage, when soluble solids reach 15% and the fruit slips free of the stem If enough bee stings are present across a majority of the fruit rind, the interior fruit “watermelon meat” or “honeydew meat” will almost assuredly be sweet and juicy. The methodology seems to be originating from insect feeding as the fruit grows on the vine. Insects “smell” the fruit aroma or sweating, bite the fruit rind causing the fruit to bleed sweet nectar, from which they can drink. The bite heals into small brown “bee stings”, causing the appearance of ridges or a zipper type of effect on the rind. Find a melon with one or two full, deep, wide zippers running the fruit length from end to end and you probably have the sweetest melon in the “briar patch” and should be a hit with your guests.
July 23rd, 2007 at 5:03 pm
Any idea on how long it takes the watermelon fruit to ripen? I have several growing and I’m curious (and impatient.)
July 23rd, 2007 at 5:22 pm
Hi Jennifer, the time to maturity for watermelons varies depending on the variety that you are growing. Some of the smaller, early maturing varieties are listed to mature in as little as 70 days. While the larger, full-sized watermelon varieties can take up to 100 days to mature and ripen the first fruit.
August 3rd, 2007 at 3:52 pm
I’m trying to grow seedless watermelons, and they are hollow sounding but not as big as a basketball. I’ve never done this before. there are only two developed watermelons so far, but several blooms and marble size ones. I hate to pick it too early, but it’s not getting any bigger and I hate for it too go bad. Any suggestions would be very helpful. Thank You Sharon
August 3rd, 2007 at 6:24 pm
Sharon, if your watermelon passes the majority of the tests listed above including the color change underneath, then go ahead and harvest one of them. Give it a few days if you want to play it safe since you don’t have much margin for error. Use the quality of the first melon harvested to help determine when to pick the remaining fruits. The marble sized watermelons may not have time to grow and mature before the season ends.
September 2nd, 2007 at 4:02 pm
I have some very large black diamond watermelons but the flesh is pale. They are pretty sweet but I was wondering why they are not bright red. Any idea?
Thank you
September 2nd, 2007 at 8:26 pm
Penny, are you sure the fruits were fully ripened? I know that some watermelon varieties are different shades of red, or not even red at all. You can find watermelons that are yellow-fleshed, orange, pink, and even white. I’ve never grown the black diamond varieties so I don’t know how red the flesh normally is, but if the vines are healthy and productive, and the fruits are sweet, crisp, and flavorful, I wouldn’t worry too much about the color.
August 22nd, 2008 at 9:17 pm
My wife Marcia plucks a straw out of a broom (she even does this in the grocery store) and lays it across the watermellon (width) if it aligns by itself length wise with the watermelon it is ripe and a good one. I’ve never seen it fail and as a member of the scientific community I have no idea what causes the damn straw to turn. Try it it it does work!
Dave
June 11th, 2009 at 9:11 pm
What is the scientific reasoning for a broom straw to turn on a ripe watermelon? What causes this to happen?
June 24th, 2009 at 10:26 am
To answer Barry’s question about picking a watermelon with a broom straw. I’m a physics teacher. It’s all about magnetics. The straw acts like a compass needle. The riper the watermelon, the more magnetic it becomes, causing the broom straw to turn, towards the magnetic activity, just like a compass needle. So, there you have it. So, if, when you place your straw sideways on the bottom of the watermelon, the more it turns towards longways, the riper the watermelon. I love doing this at the food market. I usally draw a crowd and end up picking one out for a lot of folks.
August 10th, 2009 at 11:21 pm
I’ve never heard about the broomstraw trick, I’ll have to try that. I have heard a lot of people say that they look for beestings in a good watermelon and I just have to say that that is so stupid. Bees wouldn’t have any reason to sting a watermelon. It isn’t a flower and they can’t get any nourishment from it. The second fact is that bees lose their stingers after they have stung anything. It has a barb on the end of it and using it causes their death. What would they sting a watermelon? *rolls eyes*
August 18th, 2009 at 11:49 am
I don’t get the physics behind a magnetic piece of straw. Static build-up I might buy. My girl’s grandad told her about testing a melon with a straw, we tried it and it seems to work. But WHY? I don’t know any type of physics that allows non-metals to hold or create a magnetic field. Are there trace amounts (of metals) in the melon? What generates the field and how can a straw possibly act like a compass needle. I have seen this ‘dowsing’ work, I don’t believe in sympathetic magic so there must be a logical reason. Sorry, but I don’t buy the ‘physics teachers’ magnetic field theory.
August 20th, 2009 at 9:49 am
I have harvested our first watermelon & am not sure if it is over ripe or wasn’t quite ready. The flesh is pale red and not crisp. The seeds are white (but big, not the little ones like in the seedless melons at the store). There is a star shape hollow area in the center when we cut it. The rind is not smooth, rough all over. The bottom was whitish & it always sounded hollow to me so that test was difficult. Thanks for any help you have. We have 2 more melons growing!
August 20th, 2009 at 5:11 pm
Heather, the problem could be related to a condition called “hollow heart” that affects watermelons. It’s more common in seedless varieties but can occur with seeded varieties as well. Hollow heart usually occurs during periods of excessive rain or if there is too much nitrogen applied to the soil. I would keep an eye on the other melons and use the tests above for testing watermelon ripeness and hope for better results. Good luck.
September 7th, 2009 at 4:42 pm
My brother-in-law just yesterday showed me the “straw trick”, and it’s an amazing thing, but like Mr. Field says, I find it hard to believe that melons become “more magnetic” as they ripen. Can anyone out there suggest another solution to this phenomenon?? Are you sure this works ONLY on ripe melons? Can the position of the melon (north/south, east/west)affect the results? Does time of day matter? Well… anyway… I’d like to know why this works!
November 12th, 2009 at 8:20 pm
Fresh, ripe fruit vibrates.
Just as we vibrate.
We have a vibration of around 6.5 thousand angstroms.
Most fruit vibrates at 8-10 thousand angstroms and the vibrations drop for over or under ripe fruits and at their peak when fruit is perfectly ripe.
Search ‘BOVIS SCALE’ ‘ANDRE BOVIS’ ‘ANDRE SIMONETON’ ‘THE VIBRATIONS OF FOOD AND DRINKS’
Possibly could explain the straw theory.
I am definitely going to try it out next time i pick a watermelon.