I would like to plant a flower garden starting from bulbs/ seeds, when should I plant them?

I live in Northern California.

I would like to plant a flower garden starting from bulbs/ seeds, when should I plant them?
Bulbs can go into the ground as soon as it is workable. Seeds should wait until after the last frost is anticipated.
Reply:if you bought the bulbs and seeds in packets, check the label as to when the best time of year for each different plant is. if not, you can always take them down to your local nursery for a bit of advice