One of the biggest questions that come up for people growing watermelons is when to harvest them. The first response I received when searching the university agriculture sites was often “it’s very difficult to know when to harvest a watermelon.” There is of course, the “thump” method, but that seems to be only for those with a very sophisticated ear who’ve had a lot of experience with thumping.

But here are some guidelines:

1. When the little tendrils near the attachment to the watermelon start to grown.

2. When the bottom starts to turn yellow or white.

3. When the middle gets a bit of a rough texture.

The truth is once you get to be an experienced watermelon grower like I am (ha!) you can tell when a watermelon is getting close -- they’ve gotten to the right size and they’re symmetrical in that size. That’s when you can start looking for the other clues. Even if you pick a little early (which I did on one), it’s still yummy – just more on the pink vs. the ruby red in color.

Here are some other fun watermelon facts.

From the University of Illinois http://www.urbanext.uiuc.edu/veggies/watermelon1.html:

Nutritional Value & Health Benefits

Watermelons are low in calories and very nutritious. Watermelon is high in lycopene, second only to tomatoes. Recent research suggests that lycopene, a powerful antioxidant, is effective in preventing some forms of cancer and cardiovascular disease. According to research conducted at the University of North Carolina at Chapel Hill, men who consumed a lycopene-rich diet were half as likely to suffer a heart attack as those who had little or no lycopene in their diets.

Watermelon is also high in Vitamin C and Vitamin A, in the form of disease fighting beta-carotene. Research also suggests that the red pigmented foods provide this protection. Lycopene and beta-carotene work in conjunction with other plant chemicals not found in vitamin/mineral supplements. Potassium is also available, which is believed to help control blood pressure and possibly prevent strokes.
On the site you’ll also find a fun recipe for Watermelon Granita and Watermelon Smoothies.

Ohio University gives a good primer on the history and growing of watermelons:

http://ohioline.osu.edu/hyg-fact/1000/1626.html