lilacs:

What kind of heat are you giving it? Watermelons germinate best when both day and night temperatures are consistently high, say from 75-80 degrees. Bottom heat from a seed germinating mat or placing near a radiator or other consistent heat source usually does the trick. Watermelons do seem to take a little more heat than other cucurbits.

Seeds that have been in moist ground 19 days are dead. With proper heat, watermelons should emerge in 3-5 days.

Don Yellman, Great Falls, VA

Oh, dear. They're in my spare room with all the other seedlings. It's warmed up in the past couple of days now that the weather's better, but previously it was actually a little on the cool side.

I'll try putting them outside under a hot hat. As a last ditch effort, I'll just direct sow in another couple of weeks. It's hot now, but the nights still go down to 50 degrees.

I'll think about investing in a heat mat for next year. Thanks for the info.

Well, I'll be darned. The watermelon seed that I planted over three weeks ago--and pretty much gave up on--sprouted yesterday!

The two others I had put a little closer to the light, so that they might be a degree or two warmer, and that might help germination. There might be hope for them, too.

I suppose it sounds silly, but I was so delighted to see that little sprout breaking soil.

Hey, I had a sequoia that I had given up on come up two months later ;) Congrats on your watermelon :) I assume that you know to be careful, with the peat pots, of not letting them dry out, as they're prone to do. Back when I used peat pots, I would water them from underneath by keeping them in trays that would hold water; that seemed the most reliable way. Squash and melons get big quickly, and when they're big, they drink like horses.