I googled quantity seeds, and found this site:

http://www.cheapseeds.com/3600-California-poppy-seed-mix-p-1080.html

Have no idea of the service, but it's cheap!

Cara in Sac

I've seen 4oz packages at HD. Last year they had all kinds of them and mixed with others also.

Have you tried www.valueseeds.com? I've bought seeds from here before.

Have you looked at Larner seeds? They sell in bulk.

Here is a link that might be useful: Larner seeds

I really like this idea. Cheap Seeds also sells native Chinese Houses, Baby Blue Eyes, Blue Flax, and California Bluebells in bulk. Those would be reasonable candidates for vacant lots too, although I doubt that as many of them would sprout as of the poppies. Some would probably sprout, though. Baby Blue Eyes prefer a little more shade than the others, so maybe you could use them for any occasional partly shady corners where trees might overhang the vacant lots.

ltecato, have you ever seen any articles on guerrilla gardening?

If you do sow seeds and get some poppies going, they are really good a re-sewing themselves for the following year.

ltecato,

Just a warning--California poppies are beautiful, but they can be quite invasive. That might actually be a plus in a vacant lot, but if there are neighbors with actual gardens you might be doing them a disservice.

Matt

Not to encourage lawlessness here or anything, but the best varieties for hardiness are the ones grown by CalTrans. I have collected those seeds (and others from around the state) from around a freeway overpass and they did just fine in my yard.

If you can find seeds for Tidy Tips and/or Gila tricolor (Bird's eye Gilia), they are hardy and prolific as well.
I had a dwarf lupine (arroyo/ nanus/? can't remember the name that did well sowed in my median strip.

Clarkia's will prolong the bloom into early summer.

wanda

Thanks to all for the feedback and advice. Larner seems like the most promising source because they seem to sell in bulk. I'm very much into the idea of guerrilla gardening. I've spent the last year or so trying to transform the barren hillside behind my apartment into a succulent garden. Besides the poppies, I'm hoping to establish some plants that attract butterflies and hummingbirds. They won't be getting any water aside from rainfall. I'll do my best to make sure I throw my seeds where they won't invade any one's garden. With any luck, my neighborhood will look better this spring. Thanks again.

LARNERS SEEDS they give generous amounts of seed and the germination is unbelievable

Thought I'd update---I just got a catalogue today from www.wildseedfarms.com, and their prices for CA poppies are 1 oz 4.35, 1/4 lb. 7.75, and 1 lb 17.00.
And they have some nice wildflower combinations too!

Carla in Sac