So I've just discovered why I have such rotten luck with planting seedless watermelons. I've always thought that I could direct sow watermelons, and do okay. Apparently that may be good for open-pollenated or normal hybrids, but seedless (triploid) watermelons need more care. When I started looking, I found quite a few sources that said soil temps need to be 85-95 degrees (F) and that soil must be damp, but cannot be wet. In years past, I planted directly, in soil that was probably only 75 degrees, and soaking wet. I guess there are differences in the vigor and seed coat that make the moist, but not wet soil, and warmth important.
We shall see. I've just started a test of "Indiana F1" from Hollar Seeds which is a triploid/seedless. They are in the large Jiffy pellets on my heat mat. I'm also germinating Cannon and Congo open-pollinated varieties. If I get good germination on the seedless, the OP varieties will be the pollinators. If don't get good germination on the seedless, I guess I will be growing Cannon and Congo.
An information sheet from Purdue University is at: http://www.extension.purdue.edu/extmedia/BP/BP-62.pdf . If you have a regional bias for a southern university, try http://aggie-horticulture.tamu.edu/extension/newsletters/vpmnews/jan01/art3jan.html . There were many other resources that described similar conditions for germination, just Google "watermelon triploid germination"
I'm passing this along in the hope that I might save someone else from the disappointment that I've had in previous years. (We'll see what happens this year.)
David
Germinating Seedless Watermelon
So the heat makes a MAJOR difference. Seeds were planted Monday night and there are half a dozen poking through already. These are all the seedless variety. None of the seeded types have shown anything. You can see in the photo that the pellet is only slightly damp, and not at all wet.
David
Looking good David. When do you expect the soil temp to hit 85°? Or does it not matter once they have sprouted? Here in Phoenix we are experiencing an unusually cool spring, temp at my house this morning was 54°, with an expected high of just 78°. We *did* hit 100° a week or so ago.
My tomato plants are happy but the tepary beans have not sprouted, two melons that got started when temps were a bit warmer have died, and no sunflowers seeds have sprouted! Weird weather but if my tomatoes produce, all the rest will be forgiven.
Thanks for the info.