I intruded on a veggie thread started by @subdood_ky_z6b , and while he was kind enough not to say anything, I felt bad but wanted to have a little watermelon discussion so I cut and pasted my original post in the other thread to here. So some parts of the following entry may not make sense since it came from a prior thread, but it should be the basis for starting a good discussion :
Watermelons are the one thing I actually consider myself an experienced grower since I've grown them for more than 20 years, dozens of varieties, many techniques, and so on. This year my trial watermelons are:
Royal Golden (2ed trial)
Mississippi Cobb Gem
I said I have 4 that I always grow and that is true, but over the years that has really gone to 6. These are the watermelons that I've grown many many times and year in and year out find them to be the best overall watermelons you can grow. They rank highest on taste and general health and toughness of the plants- meaning they taste great and are pretty easy to grow. By all means, if you were only going to grow a few watermelons, these are the ones I would recommend.
1) Orangeglo - This is my all time favorite watermelon and my personal favorite, hands down. It is certainly the sweetest, but the taste is also just a little bit different from other watermelons. Nothing dramatic, and hard to explain, but just a little more "fruity" and not just purely sweet (though its the sweetest). If you check most university brix tests, this one is almost always listed as the sweetest one they tested.
There are a couple (minor) negatives which I must disclose. First and obviously, it is a yellow watermelon. Most Americans grew up knowing and eating nothing but Red watermelons- they are the epitome of summertime and American. Many, not most, people will just never warm up to and accept yellow watermelon the way they do red. If they were blinfolded they'd always pick this as the best, but since friends and family eat in large part with their eyes, yellow watermelons are often considered a gimmick or experiment or etc. A lot people just feel a good watermelon must be red. The other negative with this one is that a fair number of them will develop hollow spots in the middle, especially when they get dead ripe. Its not all that common but does happen in a fair number . It doesn't really effect the taste but its just a little disappointing to open one of these and find a big hollow spot where you were hoping to find the sweetest, best meat- in the heart. But its not common enough to keep me from rating this my favorite watermelon. Many people here say Desert King, also a yellow, is their favorite but I haven't tried it yet (Baker was out this year).
2) Charleston Gray - You mentioned that your Bro in law may try them this year. I bet he will be happy. They tend to be among my first ripe watermelons, the vines are quite productive, and they are a very good tasting melon. They are among my standards for all these reasons. The only down side is that it is fairly common for them to get a soft-spot on the end of the melon as they grow and then they will start to rot from that end back toward the stem. Also, Charleston Gray tend to be a little more variable than my other standards, meaning sometimes they just aren't all that sweet, even when grown in same garden at same time and same weather. But over all, these are just really good watermelons. They are long, non-striped. I like long melons but that is just me, I think maybe most people like round melons.
3) Jubilee - One of the most popular watermelons, and for good reason. Its the most famous of the long, stripped melons and can get quite large (30 pounds and even more isn't unusual, and 20-25 pounds is very common)/ I find these to be one of the most dependable watermelons, almost always turning out the same sweet, great tasting flesh. Just an all around great watermelon
4) Crimson Sweet: Probably the single most popular watermelon in American and maybe the world, and for good reason. These are wonderful, sweet watermelons that taste great, are fairly easy to grow, and fun to eat. They are the classic round, stripped watermelon you see in the grocery store. Size can vary considerably but most of mine average around 18-20 pounds. Being round they fit in the fridge better than the longer ones.The slight downside is they can be quite seedy and the seeds are a little harder to remove than they are with long melons, but its not a big deal to me. These also have thick rinds which lets them ship well without cracking- which is proably one of the reasons they are so popular commercially.
5) Black Diamond - This is a great tasting, easy to grow, large round watermelon. Overall it just has a great, sweet taste and is productive. They also will hold on the vine quite a bit longer than other varieties. Their appearance seems to put some people off, perhaps because for some reason you very rarely see solid, dark green melons in the grocery store. Many people consider these to be heirloom and/or "country melons", perhaps because they are more common at farmers markets and roadside stands than at Grocery Chains. But I find them to be solid, dependable melons worthy of inclusion on any growers list. You wouldn't be disappointed.
I answered your question so thoroughly because I'm often asked for my "favorites" list so I thought I'd list them along with an explanation for you and others who might be curious. Of course, there are scores of watermelon varieties and just like peach, plums, and apples, most gardeners have their own favorites and I some may mention them here. Even these 4 of my 5 "standards" might not even be my all-time favorite, best tasting watermelons. But they are near the top, easy to grow, and don't have tje downside that some that I might even like better may have. For example, I think a good Georgia rattlesnake watermelon can be one of the best. But they are unpredictable, often turn out deformed, and are really hard to tell exactly when to pick. So while a perfect GA Rattlesnake might rate higher to me, its not consistent enough to be on my "standards" list.
I'd love to hear other's view on watermelons.