I was set to sow these asters indoors today, but then I checked the propagating spreadsheet over at that OTHER site (

) and read (to my dismay) that they have to be in the freezer first for a minimum of 5 days. . . . which kinda explained why only 2 of 144 seeds sprouted last year! (This info wasn't on that spreadsheet last year!!) So I put the seed packet into a Ziplock container, sealed it and chucked it in the freezer, to sow. . . .later. But the vendor specs do not say anything about needing scarification first,
My FIRST question is: how MUCH later?? How long should I leave them in the freezer???
Yes, I know these seeds can be directly surface sown after the last frost; between a heavy squirrel population, lots of various birds and a flock of marauding crows. .. . .surface sown seeds are eaten almost immediately.
These asters mature height is 20 inches, they bloom early summer to early fall and their average germination time is (vendor reported) 7-21 days. No time interrval is given for sowing/transplanting/etc to first bloom, While my intention is to start them indoors to give them the opportunity to sprout & grow, I do NOT want them to outgrow my other indoor starts: the tallest of my other starts (before transplanting) is 12 inches.
My average last frost day is April 28, so ALL seedlings will be transplanted OUTSIDE May 1, am (since I live in a 1 bedroom apt, my gro station is in my living room and I look forward to dismantling my gro station May 1, pm, and having more room!!).
This will be my third and last year to grow these asters!! Please help me. . any advice will be appreciated