I've been reading about winter sowing on this forum for awhile and have decided that this winter it is a go. I live in zone three and have been collecting the two litre pop bottles to give it a try. I've been elected to redo a huge flower bed at a school with students and so would like to winter sow some annuals that will bloom before the end of June and will be blooming after the students return in September. From all of you experts out there, please give me some advice as to what annuals you think I'd have success with. I have saved lots of marigold, petunia and zinnia seeds from my own flower garden. Would these be good choices? Tell me what is successful as it is a huge area to fill and I want the students to witness this approach to gardening. Can you use any potting mixture?