If I understand, the elevated bed will have the lower 6 inches of gravel and 6 inches of soil on top of that. Seems to me, if I were a root, put out good growth and hit 6 in. gravel, adios good root system. Root systems on TBs can go down 18 inches! I think your best bet would be to have a fast draining soil if you have summer rain.

You can bury the soaker hose to prevent sun rot. To determine when to soak the bed will depend upon how dry the soil is. Iris like to get dry between soaks.

Hopefully someone from Florida will have more info. What city? Good luck.

-I didn't know you could get iris to last in Florida. The only person I knew of that had them down there put them in pots so he could artificially give them winter chill. Hopefully Walter will jump in here.

I am another that didn't think tall bearded would perform well in Flordia because of the weather. One reason I will never move to Florida.

littlebit

I was thinking 6 inches of rock below the dirt but I wasnt sure how much below the dirt since I did not know how deep the root was.

I did have irises when I lived in Alabama but they just grew everywhere. It didnt require any special work. It sounds like I am doomed for bearded's in Florida. Maybe there are some less common species that will bloom here. I will have to do some more research before I waste time building a complex bed for something that will die anyway.

I do have "african" irises here. They sell them everywhere. They are plain pale lavander and/or white. They are pretty but not really what I had in mind.

Seavee,
I have read of people having certain TBs that made it but I didn't keep notes.
If I remember, Louisiana Iris do well. They are gorgeous im my opinion. Dietes (African iris) are a great low maintenance landscape plant but they don't satify my iris love either!