"I have heard a tradition that says that the test for whether the soil is warm enough or planting is to sit on it bare..."

I'd be worried that by the time the soil is that warm, two things will happen:

    1. The remaining growing season will be too short for most crops
    2. Spring has turned to summer, and there will not be enough
       rain for germination.

As a gardener, I think the temperature and moisture of the soil matter far, far more than the state of the moon.

People, now, are a different story. I used to work retail, and store managers were sure the nuts came out when the moon was full. I don't mean pecans and walnuts, I mean nutty people.