Perennials require a 2-3 month cold treatment (40F)
Lightly cover seed soil temp 70F taking 7-10 days to germinate (sow annuals where they are to grow)

Could you tell me wether they like light or shade and what type of soil. How frequently to water? What USDA Zones they can live in and how tall they get?

May be a common name issue -

California bluebell, desert bluebell can both be common names for Phacelia campanularia. If that's what you have:
A hardy annual native to the western US, adapted to very arid environments. Prefers full sun in very sandy or well-drained soils. Sow, seeds only lightly covered, in early spring, seedlings are not winter hardy.

Germination in 15-30 days @ 60F-70F

Not all perennials need a cold time period, yes some do but not all. It is called stratification.

It looks like your flower is a native and that means that you could wintersow that one. As morz said the seedlings are not hardy. I think winter sowing would still be a good option for this one. Looks like it is a hha (half hardy annual) native to desert areas but can be grown in zones 3-10. Half hardy means that it reseeds itself freely in optimum growing conditions.

I live in zone 10, no frost. I wait for a forecast of rain in the fall, sprinkle the California Bluebell (Phacelia) seeds where I want them, and let Ma Nature do the rest. They are annuals here.

Forgot to answer all your questions. They get about 10 inches tall, grow in sun, my soil is a bit sandy and low in organic matter. They are wildflowers, probably not very picky.

Thanks so much for all your help. I'll look forward to planting them in late winter early spring.

Can you tell me when I can expect them to bloom?

In my zone I had a sea of blue for most of the summer =:)

They were in full sun and planted in soil high in organic matter.

They do get a little scraggly looking near the end.