I purchased tomato seeds from Diane's Flower Seeds and Romaine lettuce seeds from Hazzard's Greenhouse, winter sowed them in recycled milk jugs using Fafard professional growers mix and set the jugs outside in the snow back in March. Germination was about 95%.

If you aren't enjoying success with traditional, generally-recommended growing methods, perhaps a different approach will work. Gurney's has more than 50% negative customer feedback on the garden watch*dog; Henry Fields has 60% negative ratings so they may not be as reliable as you think.

Winter sowing is a USDA sanctioned growing method. There is a winter sowing forum here on GardenWeb where you can learn more about the method. It's very simple & inexpensive but highly successful. Here are a few photos of my winter sown sprouts from this year:

Heuchera/coral bells
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Phlox
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Persicaria
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Snapdragon
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I hope you find what works for you. Good luck!

I've recently grown (indoors 20C, windowsill) melon,squash,cucumbers what I did was use a peat/perlite/vermiulite mix in those 4x3 plasti trays, with a lid.

They should sprout in a week, and be ready for transplant soon after.

Hope that helps.