Try going to the forum for your region. I do believe there is a Great Lakes or Northern such region forum? There, you can get the locals to advise you who are doing the same thing. Make a post something like "looking for garden buddies near [city], MI for advice re seed starting" and they should be able to give you a Spring timetable. From my experience living in zone 6 MA, my last frost was around May 15th. Are you sowing outdoors in situ and/or indoors in a flat? Need to know more. Maybe you are doing both. Email me for my old schedule, as I am now in NC z7, but can still help. It is still too early to do much in z6 indoors without a greenhouse and heated mats, and almost nothing outdoors except for Nigella; cool season annuals which will germinate when ready. Sure, go ahead and sow your Cosmos. They will know when to germinate. Mine in zone 6 MA germinated in April sometime. Hope that helps.

Thanks Al. I'll keep that rule in mind. Now that I have more than 1 plant per pot, do I need to clip out the others immediately? I figured to wait a week or so to be sure I had good transplants, and then trim out any extras. I use a manicure scissors to thin them, so I don't disturb the adjoining plant.

FWIW, I don't dead head my pansy or viola's. They have been forming seed pods which have been bursting all year. So mother nature is sowing them all summer for next spring. What that means is sow whenever you are ready as they will germinate when conditions suit. SCG

Last year, I sowed ornamental cabbage (not kale, but close enough) on 7/15 and they were up in 4 days; this year, they were sown on 6/21 and were up in the same 4 days. That said, the seedlings are still pretty small. Last year's plants grew slowly and didn't show any color until early December, after which they were killed off by some serious frost. I started them a bit earlier this year, but I really think I should have started them even earlier. Your zone is similar to mine, so you may not have enough time to get them to a good size for fall color. But, hey, you never know. I'd give them a shot anyway. My eaten-by-something and less-than-satisfactory effort from last year: PV