i am not aware of any annual .. or any plant.. that will stop weeds... just because you plant it in a given space ...

the one thing the will significantly reduce weed seed from germinating.. is a good thick layer of MULCH ...

but not necessarily the layer of COMPOST your threw down last year ...

ken

Zinnias, sunflowers, cosmos, larkspur, marigolds, moss roses, are carefree full sun lovers, all usually yield satisfying results if seeds are scattered.

Has the cardboard decomposed by now? If you didn't have a crop of something dropping seeds there last year, it's unlikely you'd get an overwhelming explosion of something this year, but it's always good to be ready & vigilant, especially after removing shrubs that had kept the ground shady.

The cardboard, for the most part, did fully decompose... What didn't is all gone as of now because it was only smaller pieces that the wind blew all over...

I'm a little over 60 miles south of Chicago, so what day/night temp's should I be looking for to scatter seeds? Starting tomorrow night, the night time temp's will finally be consistantly in the low-mid 50's... 35 tonight...

Well, the leaves and the compost was a little extra that I had, so I figured it would help the Soil

==>>> absolutely ... good thinking ...

but it isnt going to do anything for weeds this year... and that is why i suggested you start thinking about a mulch ...

just pointing out the difference in the words .. and the uses ...

good luck.. sounds like you are raring to go ...

ken

The individual seed packets should have planting instructions/dates, and approximate time it takes from sprout to flower. Some do best if left exposed, some covered a bit. Sounds a tad early up there yet. You might want to do them over a few weekends, to spread out the show, if your growing season allows.

I agree with keeping ground covered with mulch but seeds don't sprout that great in mulch (unless you happen to not want them to - LOL!) You could get the seeds going first, then mulch around plants. Turning a pot upside-down over plants can make it a bit easier to do that w/o accidentally burying them, if they come up more individually than like a carpet. Or you could put the mulch down, then move it back in spots or rows to scatter seeds, so they can contact the ground.

Next time you're considering a smother, use the cardboard on the bottom,
with whatever else on top. Looks like "instant bed" that way, won't
blow around, will dissolve/decompose completely, and makes a solid cover
over the soil, to make sure anything perennial under there can't keep
growing, unless there's a hole or seam it can exploit. Overlap seams
well.

Miniature clover

Low care and water needs would be some good sedums, such as blue spruce sedum.

Bee balm, zinnias, and marigolds reseed well if it is not all covered in mulch.

Purple queen or wandering jew will also become a thick cover there every year, but they do die back with winter temperatures. The advantage of growing these is that they will do fine to come up through the mulch and continue spreading in that area (of course, I don't know how thick the mulch is but as long as it's not too thick, new stems can come up).