Well, if this post was meant only as a personal communication, I'm not Morz8, but...

I see no reason that plain old water couldn't be used to get rid of any remaining cornmeal. Wintersowing containers don't really need to be sterilized, and cornmeal is a very weak herbicide, so there's no need for any unusual methods.

Ladyrose, I've looked for suggestions for neutralizing or buffering agents for corn meal present and don't find anything definitive, and don't see anything to suggest baking soda or charcoal would be helpful.

I suspect Brandon is right. The edible corn meal would be weaker than horticultural refined corn gluten is my thought. I think you said you had used only a little in your sowing medium mixed in. I wish I could be of more help and had something specific other than watering your containers but I really don't. You may not have even added enough meal to be problematic, I've only noted the articles for organic weed control using it and don't have experience in amounts.

Thank You Brandon7 and Morz8. I've been using yellow cornmeal from the beginning of my first time Winter Sowing. I never associated the jugs that did not germinate with cornmeal being a possible problem. I just have trouble getting lobelia cardinalis, lavender, pearly everlastings, and Yvonne's salvia to germinate. Let see what happens this season.