Nennie--I'll try to answer all your questions. I think you mean self-seeding don't you? Hollyhocks are easy to grow in all types of soil.They love full sun.Hollyhocks are mostly biennials though if they doing well where they are planted then they will self-seed.
My local librarian just told me that Hollyhocks grow in zones 1 thrugh 24. She referenced the Western Garden book. I also went online to ehow and brought up an article "How to grow Hollyhocks in Phoenix" which was very interesting.You can also type Hollyhocks in the search box to bring up all kinds of gardening info about Hollyhocks.I don't know where you are but I know that the Sunset Books have a breakdown on the zones.
There is an excellent videeo on YouTube about growing Hollyhocks! Type in tree and Plant Care:Growing Hollyhocks--- in the search box on YouTube to bring it up. She says they are so easy to grow and that they will overtake your garden (which might be a good thing in some instances!)