PlainJane this will be my third year growing them. The first year was 2015? (I'm not sure) I followed the instructions in the third comment on this article
https://ask.extension.org/questions/296831
It worked perfectly! I was giving chokes away to family and friends.
In 2016 everything in my house was hit by a bad case of fungus gnats. Very few plants survived, the artichokes did not. I didn't grow artichokes in 2017.
Last year (2018) I didn't get seeds until March so I bought plants in May instead. They were pretty but never got any bigger than about two feet tall, no chokes.
I'm doing exactly what I did in 2015 (or 2014?)...starting three in mid January and three in mid February. From there they will go in a makeshift cold frame in late March/early April or my garage if it's below freezing. Then they will be planted out in early to mid May. Fingers crossed it works again! I'm growing a mixed packet from Botanical Interests that contains green and purple artichokes.