Ive grown petunias for years and never had them self seed, I usually wintersow those, as well snaps when I do them...

However, I direct sow many my cosmos every year, never bothered with wintersowing those.

I agree with the snapdragons, they are very thin and fragile from WSing. This year I used 'Azomite' in my potting soil. I got low germination but the plants are very healthy looking. I also noticed that you have to becareful with greenhouse flower too, the also come out fragile. But I keep trying. I luv WSing.

My petunias don't really re-seed themselves and I only get the occasional volunteer, usually far away from the original plant. That said, the celosia I had in pots on my patio seems to have resown itself tremendously (and I don't want it this year, lol). I used walls o'water for three tomatoes this year and had a # of volunteers in the places I put the walls. It was apparently much warmer there than in my jugs where the tomatoes didn't do so well this year.

For me letting Larkspur, Nigella and Poppy do their own thing produces healthier, robust plants....I never had good results sowing them. I just let them re-seed or broadcast seed in fall for spring/summer blooming.
Last October I both wintersowed and broadcast two different Columbine at the same time and the ones I broadcasted are anywhere between 2" and 8" high.....while the ones in the containers are inky dinky seed-leaf stage! I've been digging these up and transplanting quite a few of these to other spots within the garden :)

I totally agree that wintersowing is the BEST hands down for perennials. With some annuals it is a different story. I haven't been able to have larkspur work at all with wintersowing. Last year they sprouted & I put them in the ground but they remained teeny tiny. They even bloomed while VERY small-my California Poppy were bigger than them. This year not even one sprout!

The others I have trouble with wintersowning are corn poppies and peony poppies. Transplanting them is brutal. I make sure to plant when very small but they end up dying anyways. I am definitely going to try direct autumn sowing them and see if that works for me. But I will still try wintersowing them because others have success and I don't like to give up!

Then again for some annuals like California Poppy, Cornflowers, Balsam, Zinnia, Cosmos, Scabiosa I have no trouble. I haven't even needed to wintersow cornflowers or California poppies since the first time I wintersowed because they reseed for me every year! Along with corncockle.

Just like every other gardening technique there is alot of trial & error with whatever type of sowing you do.

This post was edited by ladygladys on Tue, Jun 4, 13 at 0:14