According to our friend Google: "Moist stratification is a process wherein the seed is mixed with moistened inert material (fresh sawdust, builder's sand, vermiculite, peat moss or similar material) and stored cold for ten days to three months. Planting the seed outside in the fall (direct seeding) achieves the same results as Moist Stratification."

The question was why moist stratification doesn't kick off germination. I cannot plant these too early because the plants are needed for bank stabilization in a creek that is prone to flooding. Such flooding would clear away ungerminated and thereby unanchored seeds. So when I plant, I want them to grow, like immediately. MIght have to protect, but that's a big job. I could plant out plants, but those are vastly more expensive. So if the seeds are all downstream, that doesn't achieve the same result as moist stratification.

They won't germinate in your refrigerator for the same reason they will not germinate outdoors during the winter, also typically a moist situation - too cold. This is a warm season grass that needs soil temperatures - after stratification - of 60-65F to germinate.

Yes, I'm now seeing that minimum soil temperature for germination is 65F. That's surprisingly high. At least for vegetables, I don't think any need that high a temperature. Around here, that's mid-March. So I'll just stratify until then. That's a bit more than needed, but will likely do no harm. I may plant some indoors a month or two earlier, to see if I can have some plants ready to transplant by early spring. These are highly shade tolerant, so that ought to work.