Good watermelon or bad watermelon? Growing conditions and storage make a huge difference in watermelon flavor and texture, but these tips will help you choose the best available watermelon. Some of these tips are for when to pick a watermelon from the vine, others apply to both vine watermelons and those at the grocery store or farmers market.
Ripe watermelons are a little trickier than muskmelons. Muskmelons slip right off the vine (i.e. come loose on their own) when ripe. Watermelons don't fall off the vine when ripe. Uncut watermelons are also less fragrant than muskmelons, because they don't have that open end where the vine was formerly attached. You will never find me sniffing watermelons in the grocery store, but you may find me sniffing cantaloupes. (I do my own stunts. 😉 )
Finding a Good Watermelon – 4 Clues to Tell if Your Watermelon is Ripe
Back in my late teens and early 20's, my jobs at the family catering business included picking out the watermelons and carving the watermelon boats for parties. I was known as the resident watermelon expert, almost guaranteed to be able to pick out a good watermelon, if there was a good watermelon to be found. Unlike some fruits, watermelons do not ripen further once they are off the vine. Choose carefully.
Ripe Watermelon Tip #1 – For Watermelons on the Vine – Make Sure Your Watermelon is at Full Growth
If you're watching the patch, you can tell when a particular melon is large, well filled out, and hasn't changed significantly in size for some time. Days to maturity will give you a rough estimate of expected watermelon ripening time. For first time growers, you can check the expected size on the package and weigh them if you want, but the best way to tell is to observe the growth habits of the melon.
Ripe Watermelon Tip #2 – For Watermelons on the Vine – Check the Little Curling Tendril Located Where the Watermelon Stem Joins the Main Vine
Right where the stem to your melon joins the main vine, there should be a little curling tendril or curly cue of vine. If the tendril is still green and springy, the melon is still growing.
If this little tendril is brown and dried, odds are your melon is as ripe as it's going to get. Sometimes all your vines may start dying back before you've harvested, not just a tendril. Ready or not, this is as ripe as your watermelons are going to get.
Ripe Watermelon Tip #3 – All Watermelons – Look at the Underside of the Melon
The under side of the watermelon where it hits the ground should be buttery to dark yellow in color. This is called the field patch. If it's as pasty white as a bald guy's head in the middle of a Wisconsin winter, it probably hasn't reach peak ripeness. This tip is good for buying watermelons, too.
Different growing conditions and different types of melons will produce a range of colors (inside and out). Much of our summer was cool and dry, less than optimal melon weather. When rain finally came, it came as a deluge, which sent the slug population skyrocketing. When I flipped over our first ripe watermelon, I was frustrated to find slug damage underneath. Thankfully the rind was thick and the damage didn't go all the way though. You can see this one only has a light yellow tint. Warmer weather usually yields a darker yellow bottom.
Ripe Watermelon Tip #4 – All Watermelons – Listen to the Sound
This is a classic, and the internet is filled with descriptions of what the sound should be when you thump a watermelon. Most say “flat” or “dull”. I think that's a poor description. For my part, “flat and dull” is the sound you get when you rap on something like a giant zucchini – or an underripe watermelon.
A ripe melon should have a nice, deep sound, more like a drum or knocking on a door. I did a quick video (below). My Powershot D10 doesn't quite do it justice, but you get the general idea.
Here's the end result. Given our uncooperative gardening season, even with the landscape fabric and other tactics to create a warmer microclimate for the melons, they didn't ripen as close to the rind as I would prefer. They still had good watermelon flavor and they were extremely juicy because of recent rains. Once cut, you can tell the melon is mature by the dark seeds and the cavities around the seeds.
The Best Way to Store Watermelon
Before our melons were ready, I picked one up at the grocery store that I really shouldn't have bought. It was during our brief hot spell this summer, and the melons had obviously been stored too cold because they were chilled and sweating in the bins. Sure enough, I got it home and the flavor was bland and the texture was mushy. Melons like it warm! Room temperature storage also makes them more nutritious.
From the article “Watermelon Fruit nutritional value health benefit” by Ray Sahelian, M.D.:
Watermelons stored at room temperature deliver more nutrients than refrigerated or freshly picked melons. Researchers tested several popular varieties of watermelon stored for 14 days at 70 F, 55 F and 41 F. Whole watermelons stored at 70 degrees Fahrenheit, which is about room temperature in air-conditioned buildings, had substantially more nutrients. Compared with freshly picked fruit, watermelon stored at 70 F gained up to 40 percent more lycopene and 50 percent to 139 percent extra beta-carotene, which the body converts to vitamin A. Watermelons continue to produce these nutrients after they are picked and that chilling slows this process.
The usual shelf life for watermelons is 14 to 21 days at 13 degrees Celsius (55 F) after harvest. At refrigerated temperatures, such as 41 F, watermelon starts to decay and develop lesions after a week.
So don't stick your melon in the fridge until it's cut (or chill only briefly right before serving). Once it's cut and refrigerated, eat it up ASAP.
Good Watermelons for Northern Growers
Growing watermelons with a fairly short growing season can be a challenge, but with a little extra TLC we manage a good harvest. (Leave a comment if you would like to learn more about how we grow watermelons.) Some of our favorite watermelon varieties include:
Even though Orangeglo and Yellow Petite don't get red, the same rules still apply for determining if they are ripe. Here's one of my favorite watermelon photos from a few years ago.
Thanks for reading! We love your shares and comments. How do you enjoy your watermelon?
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Originally posted in 2014, updated in 2017.