i wouldn't think you would want too rich of a soil for watermelons. i know when i lived in ga. the farmers planted watermelon on "lay by" land. land that not been cultivated in a couple yrs. just my memory.

william

I'm still learning myself but I think a lot of gardeners recommend sowing watermelon seeds direct rather than starting them in pots. That's the way I start mine and have had pretty good luck so far over the last several years.

I soak my seeds overnight or sometimes put them in a wet paper towel and wait for them to just barely sprout and then stick them in the ground. Around Mother's Day is a good time to start the seeds or even a little later.

I've never fertilized mine with anything organic or otherwise. I don't have a rule against it. I'm just a lazy gardener. It may be possible that too much nitrogen caused yours to have a lot of foliage but not fruit. (not sure) They need full sun of course.

I've grown Sugar Baby and like that one. They're small but fit in my fridge well. I haven't tried Jubilee. I had good luck with Moon and Stars both regular and the yellow fleshed variety. Last year, my favorite was Orangeglo but the year before when I grew those, they weren't as good. I blamed the weather.
Baker Creek in Missouri (rareseeds.com) has both Moon and Stars and Orangeglo unless they're out. They might be able to give you some other recommendations on varieties to try that do well in the Ozarks. If you ask them, let us know what they say.

I mark the base of the vine with a stick or something so I'm sure to get water near the roots rather than just spraying the hose over the whole area.

A good way to tell whether they're ripe is to watch the tendril (short curly thing) that's nearest the point where the watermelon is attached to the vine. It will start to dry up when the watermelon is almost ready. Patiently wait a day or two after it's dry, and you'll have a very tasty watermelon. I've never figured out how to tell when they're ripe by thumping them like some people do.

Don't give up. It's very rewarding to haul a 20 or 30 pound watermelon into the house.

I'll link the University of Missouri Extension page on watermelons below. It has some recommend varieties, most of which I've never tried and some other information. It has some seedless varieties listed too but those are generally harder to grow.

Here is a link that might be useful: MU Extension - Watermelons