variation on 'unclean' women (see next post), or planting with the moon

I was telling Moreno, the local purveyor of all things good including information, stories and intelligent conversation, of my consistent inability to grow a certain plant. He asked me when I was sowing the seeds. I told him I’ve tried at the new moon, the full moon and in between. I’ve tried sowing it dry and sprouting it, I’ve tried in sandy soil and in loam, it’s not happening.
“But when in your moon?”
“What?”
“You know, there’s a time when women can’t make bread or mayonnaise.”
“What?”
He blushed.
“What? . . . You mean my period? What, I can’t make bread or mayonnaise during my period?”
“No, it doesn’t work.”
I laughed. Where does such an idea come from? Is it somehow related to the BriBri / tribal belief that sets women apart at this time (and gives them a break from the ordinary)? Periods must be the antithesis of pregnancy, does this make them anti-fertile times and so unproductive? I would have thought it the opposite. I tried it; the bread is just as fine, the plant still doesn’t grow.