I'm not sure why you would have germination in any of them yet, the only possible early sprouter that I see on your list is aster, and that would be the perennial varieties, not annual ones.

I used to live in zone 5 and we were still having frosts at night in the middle of May. I don't think you have a problem with grass clippings, I think it's just too darn cold still for you to have a flush of germination.

I have had germination on only zinnia (about a week? and staying really small..it's chilly at night!)out of all of these in a cold frame. So I agree Trudi; I bet germination is around the corner still.

But maybe someone who knows more about the science could comment about if it is possible that the grass clippings are giving off some kind of "anti-germination gas" (smile) as they decompose? My husband (an aggie) just floated the theory that maybe the thickness of the grass clippings is keeping the soil from getting warm?

Nancy

Remove the grass clippings from half of the cold frame.
Put equal seed trays in each half
Post results
This will not eliminate the gas theory tho
Why not pack dirt around the outside edges of the cold frame? I assume it is on the ground. That is what I did.
I have my first cold frame that is about 5'X 3' with two sash windows in an A frame. I wondered about lining the bottom with bricks rather than just the ground. Would this hold more heat from the sun? Release it during the evening? Maybe when I reassemble it next year I will consider this?

Grass decompostion is going to produce heat, thinning the layer will eliminate that.

Thank you all for your help!

As far as it still being too cold, I've been using a cold frame for years with great success for all my annuals (in much colder weather than this year). Despite there still being night frosts, the cold frame holds in the heat very well. If you've never done it before, try it.

In the past I have put dirt in the bottom of the cold frame but I was thinking the composting clippings would throw some heat and thus promote germination. I guess not! I have since removed the clippings and put dirt down. It's only been 2 days. I'll see what happens.

Again, thank you all for your responses.