I'm wanting to sow somniferum poppy seeds soon, so here are my thoughts. If your soil is prepared, now. Nature's way is to sow them as the seeds fall to the ground, June or July.
Last year I had poppies that seeded themselves, appeared by fall, and were so much nicer and healthier than my winter-sown attempts, or the ones I direct- sowed in December. [I've been waiting on neighbors (one said she sowed hers, both poppies and larkspurs, last June) to give me larkspur seeds since July, but I still have no larkspur seeds. ]
The problem is that I mulch and also sow annuals, such as huge zinnias where I want those spring bloomers, and then want to amend the soil when they are done blooming. But if I sow them after November they come up late, and if we have an early heat wave, they don't last very long.
Have you tried enclosing seeds in clay balls? If you have any clay soil at all, mix it with some compost and seeds and moisten it, roll it into little balls and place them in your garden. Thin out when they sprout. The clay prevents them from blowing away or getting eaten all at once. And you don't have to transplant, just thin. (Plants hate to be transplanted!)
Another idea: place chicken wire or something else over them to deter critters when you sow them.
I look forward to other responses to your question, and the problems (and blessings) of our multi-planting seasons here in the Carolinas.
Andrea

I have larkspur and nigella that self sowed germinating now so I don't see why not.

I went ahead with sowing the seeds on Tuesday while planting my Dutch irises and allium. I'm really excited about this display, so I hope it all works out!

Thanks,
Cameron

Cameron,
which alliums are you planting or have been successful? Mine don't last very long...have been told voles are responsible.?

I planted 'purple sensation' and this is my first time for these (we built here in 2005, so the gardens are very young). I can't say yet how they'll work out. I'm optimistic as deer and bunnies are my problem instead of voles.

What poppies do you plant now? California Poppies? Shirley poppies? thanks!

yes and yes. as well as poppy somniferum- aka bread or opium poppies. Pretty much any of the poppies like cool weather to germinate and don't like transplanted.