I am trying to grow Helianthus in my garden!  Have you ever grown them?
Yes I love them, I grow several types of sunflowers, I am an expert when it comes to them, anything you want to know about them? 
How long does it take for them to grow to full height?
Well I grow a special sunflower called "H. annuus", and it takes about 2 years if I'm not mistaken. 
Wow!  That is a long time!  can you eat their seeds?
Yes you can and If the husk is solid black color, the seeds are called black oil sunflower seeds. They are delicious when salted. 
Makes me hungry thinking about it.  What type of environment is best to grow them in?
Well the most primary places to grow them are industrial forests and pine plantations in Alabama, Georgia, and Tennessee. but you can grow them in other places, It just requires extra care. 
Can I grow them well in Florida?
I'm not too sure about that since The Fish and Wildlife Service have now issued a new rule protecting it under the Endangered Species Act. So it has to be grown in certain places and under a watchful eye.