When you're paying as much for fruit as we all are these days, any hacks or tips for selecting the best and ripest are gratefully received.
It is no wonder a trick for choosing the best watermelon has been shared more than 2600 times on Facebook, and garnered almost 4000 likes!
The poster shared after asking a watermelon farmer for his secret.
"He said to make sure the dark green lines are two fingers width APART," the poster shared on a Facebook group.
"When we got watermelons yesterday, I put that to the test and cut the watermelon up.
"IT WAS DELICIOUS. I thought I'd pass the info along to our friends!!"
It sparked a conversation about the best tips.
"We were taught to knock on it, and it makes a kind of sound. Hard to describe, but you know it when you hear/feel it. Not too hard, not soft, not hollow either," one person commented.
"And my family grew melons growing up. Also there are different types so it wouldn't apply to all."
But a second person confirmed the technique: "This absolutely works! We got the best watermelon Friday from using the two-finger rule!"
"Love learning these little tips - thanks so much," another wrote.
"Awesome! Those olden day tricks really work and still do today," another added.
Other things to look for to ensure your watermelon is the best of the bunch:
A creamy yellow-to-orange mark on the melon. This is known as the field spot, where the melon sat on the ground and the deeper the colour, the longer it was allowed to ripen on the vine.
A deep hollow sound. When you knock on the melon it should sound hollow, meaning it is full of water and the flesh is firm and ready to eat.
Dull skin. If a watermelon is still shiny it indicates it's been picked before it was fully ripe.
Brown spots. These marks and webbing are where the sugars have seeped out, meaning the melon is sweeter.
Weight. The heavier the melon for its size, the more water it has and the sweeter it will be.
Round shape. The rounder the melon (as opposed to oblong), the sweeter it is and less watery.
In season. Finally, you are more likely to get a delicious watermelon when they are in season.
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