When to plant Imperial Star artichokes in Los Angeles?

My brother decided to dig up the artichokes we had and replace them with Imperial Star artichokes. We live about 20 miles South of downtown Los Angeles. We get essentially no frost here.
When should I plant the Imperial Star seeds? Can I plant them outside now? Thank you in advance for all replies.
My previous cat Rocket thought that every time I ate something he
should get some canned cat food. Marmaduke, the cat I have now,
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