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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{ 45 comments… read them below or add one }
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.
What makes watermelons rot before they have matured?
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.
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?
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.
Amazing information!!! Your Internet site is cool.
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.
Any idea on how long it takes the watermelon fruit to ripen? I have several growing and I’m curious (and impatient.)
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.
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
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.
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
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.
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
What is the scientific reasoning for a broom straw to turn on a ripe watermelon? What causes this to happen?
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.
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*
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.
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!
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.
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!
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.
The straw effect is the same as someone using a forked peach branch or whipping willow forked branch to look for water….water witchers. The watermelon has reached the maturity where it is full of water which means ripe.
So…I’ve heard that if watermelons have scratch marks from bees they will be riper, because bees can tell which ones are sweeter and they want to eat them. Is this true?
we have grown a watermelon, it was not attatched to vine anymore and when we cut it open it was pink, not bright red, still little sweet but not like a properly ripened watermelon. my question is can this make you sick or is it ok to eat (just wont be as sweet as it could have been)
The watermelon should be fine to eat, sounds a little under ripe but if it taste OK it is good enough to eat. If it was grown organically you can even juice it, rhine, seeds, and all.
My grandpaw showed me all 4 tricks (methods) of choosing a ripe watermelon. The straw trick will gather people in a grocery store, and if you’re practiced at it, the “feel” of the melons ridges coupled with the color of the nesting area (bottom) of the melon will almost always guarantee a luscious, sweet, juicy melon…..as well as an enjoyable time at the grocery store. Thumping actually takes more of a “trained” ear but if you “feel” the thump is “spongy” like the inside is full of pudding, you’re on the right path.
Look, thump, hear, feel and enjoy….
I am growing a nice crop of watermelons… im watering them religiously…but as soon as the reach about grapefruit-sized…i notice they have split open on the bottom(a 2-inch crack)… i dont see any ants in there.. im wondering whats going on???
Amy, if possible try to barricade all of the openings under the shed except for one spot and place the trap right there so that the groundhogs have no choice except to go into the trap.
Kenny, what?….im not having groundhog problems… watermelon problems.. i think you made an “oops”.
Sorry Amy, must have gotten some comments crossed. I’m not sure what is causing your watermelons to split, but could you actually be over watering the vines and causing the young fruits to expand too rapidly? How often and how long are you watering them?
I have a watermelon vine growing on a trellis. The melons are hanging suspended in the air. Any suggestions?
David, use something like a pair of nylon stockings to make a sling or hammock like support for the melons. Then tie the sling to a stake, trellis, or whatever the melon is climbing up. The stocking will give and expand as the melon grows but continue to bear some of the weight and keep the fruit up in the air. Send me a pic if you try this technique, good luck with the watermelon.
My mom’s watermelons are really small, but they dont seem to be rippening properly.
Hi, love your website, but was wondering if you’ve ever grown a watermelon in an “Earthbox” ? Also, I started some seeds a few weeks ago and was wondering if it was to late to grow my watermelon in Southern New Jersey. One more question
… Can you grow them inside the home?
Thanks in advance!
Hello,
I grew my first watermelon this year. I waited til it was pale yellow on the bottom, hollow sounding, and the tendril near the fruit had wilted. But when I cut the melon open, it was pale/light pink and bland — not super juicy either. Is this under ripe or over ripe? How can I do a better job?
Hi Bernessa, it probably is too late to be planting watermelons in this area because they like a long growing season and plenty of warm days. I also don’t think they would do well indoors unless you had a rather extensive hydroponic setup.
Fred, your watermelon sounds under ripe to me… you’re doing everything right but sometimes it just takes a bit of trial and error to get things just right. Also don’t forget the feel test to look for the ridges that will develop as the fruits mature.
This was an excellent, concise article that got right to the point without all the extra hogwash. I think the “technique for selecting ripe watermelons that relies entirely on touch” is the best method overall, since the “thump test” seems to be more trial & error than anything else. Anyway, I’ve had good luck this year with the Crimson Sweet melons and for the first time, I also grew the slightly sweeter orange-yellow watermelon variety. To the rest of y’all: good luck with your future crops and I’d like to see more & more people start being less dependent by raising their own food.
I have just picked my first watermelon ever from my personal garden. We seem to have the smaller sized ones. I always thought that the less yellow on the bottom, the more ripe it was. I think I picked it too soon. The meat and the seeds are white. I tasted it and it isn’t real juicy, however,it is sweet. I have at least 6 more melons growing as I can see and I will let them get a whole lot more yellow on them than this one did. I think I blew it on this one. Please advise what you think. Thanks for your input
Hello all,
I’m a novice gardener and just started my first garden this year. I have a question as to the “maturity” that is always mentioned for different veggies and fruits. When it says that something will reach maturity in “70 days,” does that mean that it is 70 days from when you first see the blossom or fruit growing, or is it from the point when you plant a seed and it grows from seedling to full-fledged plant?
Any advice would be appreciated! I have had moderate success with “some” of my plants this year, even though I have only about 4-5 watermelons out of about 3-4 plants. That actually reminds me of another question…how many fruit should one expect per plant? I planted the seedlings in enough time, but I’m wondering if I waiting too long to transplant them into the yard.
Hi Joe, the maturity dates listed are typically from the point in time that the seeds are sown or when transplants are set out into the garden. Watermelons are not the easiest crop to grow so that is actually not a bad yield for a new gardener. The number of fruits will vary based on the variety that is being grown, soil fertility, weather conditions, etc. Two or three melons per plant would be a good harvest. Also, if you allow too many melons to grow it can affect the size and ripening of them all.
Will do. Thanks Kenny!!!!!!!!!
To the lady who has problems with splitting – critters love watermelons, especially if it a particularily hot summer. Everything from pheasants to squirrels to quail to turkeys even deer will open up a melon to get at the sweet liquid. I personaly have had a big problem with pheasants and turkeys in the past. I put wire cages over them nowdays to prevent this from happening. I am growing Black Diamonds this year. I have picked 4 so far (one wasn’t quite ready) and this weekend I will pick 3 more all about 60lbs apiece. I have about 10 more from softball to volleyball size that i hope will ripen before the weather changes. The heat this year has been perfect for them.
My watermelon plants each produced 2 full size watermelons. We harvested one a few days early, it was okay but not great. The second one was perfect. The plants have now died and we removed the remaining 2 watermelons, which are both ripe. What is the best way to store them? In the refrigerator?