There is nothing like the taste of fresh, ripe watermelon, especially one grown and picked from your own garden. But, knowing when to harvest a watermelon can be a bit of a crap shoot and, trust me, there is nothing more disappointing than biting into an unripe watermelon.
It'll ruin your day.
Last year, we had more watermelon than we knew what to do with (full story here). However, having never really grown watermelon successfully before, we were pretty clueless about how to tell when they were ready to pick.
Once the first melons were nice and big and seemed ready, we just couldn't wait...
So, we picked a watermelon (or 2) using our uneducated assumption that being large in size meant the watermelon was probably ready to pick. We were so excited to bring the watermelon back to the kitchen and slice them open - only to be disappointed by the color, the taste, and the (LACK OF) sweetness. Many of those first watermelon we picked were simply not ripe. Size alone is not an indication of when a watermelon is ready to pick!
Unlike cantaloupes which will practically harvest themselves by disconnecting from the vine when mature, watermelons require a bit of inspection and some intuition too to know when they are really ready to harvest.
Here is a photo of the bottom (where the watermelon was touching the ground) of a harvested Sugar Baby watermelon from our garden last year. You can see here the bottom of this watermelon is quite yellow (not white or creamy). It was ready to harvest.
And here are a few close up photos of the curly tendrils that grow next to where the watermelon fruit attach to the vine. These are Crimson Sweet watermelons growing in our garden this summer and, as you can see, the tendrils are still quite green and the watermelons are not yet ready to harvest.