Every year that I've winter sown, I've always had a second round as you call it. Some of this year's second round is being sown this weekend, but others won't be sown until the second or third week of April.

Not all things we winter sow 'need' stratification (that word is just tooo long :O). Actually, about 60% of the seeds I've sown so far don't require it but germinate just the same.

Also, a lot of perennials won't bloom in their first year so whether they are sown early or not in the wsing way, it really doesn't matter. On the other hand, some do bloom their first year and will do so no matter when you ws them.

Last year I sowed some Buddleias - the plain lilac colour kind - on February 20th, and then again on April 6th. Both germinated within the same week and to me that's not enough difference to even mention it.

Our 'last' frost date here is April 28th, but I know there will be a few more after that. I will keep sowing anything that requires stra... until the third week of April. The only difference will be the placement of containers. They will not be in the sun at any time of day until mid-May. I've never been disappointed by doing this.

After last year's April hard frost, I lost several types of whimpier sprouts. I'm not sowing any of my spare seeds until after April 15th this year. I figure I'll get the tough ones going with the winter sowing, and any whimps I lose will have a second chance with a spring sowing.
As a bonus, any seeds I don't need to resow can be sown next year to fill in or expand beds. I'm trying to be pretty carefree with this WS thing. If they make it with my tough love plan, they deserve a place in my garden. If not, they either get a second chance next year with TLC or can find a new home as a dated bonus pack with someone else.

I'm looking outside at snow right now. If you had asked me earlier in the week when it was 49 and sunny, I might have given a different answer. Hmmm. I seem to be fickle. Still, today, with no sprouts in sight, I wouldn't sow those extra seeds quite yet.

Many of the WS seeds don't actually NEED the cold period, but rather have no problem withstanding it. Seeds with packets that say scarify or provide cold periods are obvious exceptions.

Good Luck
Squirrel Girl

Tiffy,
I must have spent too long typing my reply. You beat me to my answers for ProudGm's questions. Good advice you gave her. ;)

It really depends on the species. Not all perennials need to have cold stratification (or freeze/thaw cycles) to germinate :D