I'm not sure, but I don't think that the tap roots on my hollyhocks ever got even close to my foundation drains. Mine grew in morning sun, until around 1:00 or so. I eventually got rid of them due to issues with rust.

I hadn't heard of hollyhock rust, Babs, so I looked it up and found a garden web thread about it. It sounds like rich soil may be a cause, so I guess I could spade some sand into the soil, and also I suspect that the fungicide I've used on my flowering crabapple might well solve the rust problem if it did occur. I might give them a go next summer. If they don't pan out, I too, can get rid of them and try something else. Thanks for the reassurance too about the tap root length.

http://www.uvm.edu/pss/ppp/pubs/gd26.htm

I read the comments you are referring to. It is not the rich soil as far as I know. Hollyhocks grew on the top of the manure problem and looked pretty spectacular. Traditionally, that is where they were grown. I cover the soil with manure each year too and it keeps them healthy and happy. It is a conclusion when hollyhocks are growing in a parking lot that they unamended soil was not rich, etc. or that "amending the soil like crazy" did not somehow through off the balance of the soil itself. Straight, but aged, manure will be helpful in my experience.

When the hollyhocks get undermined, they get infacted. This can include them not getting enough nutrients, not enough air circulation, very wet conditions (those years with too much rain), the fungus spores also winter over on the unremoved foliage and leaves.

Other ways to prevent the rust is to grow the fig leaf type hollyhocks that are a bit resistant to rust. Remove mallow plants (Zebrina for example) that carry the rust fungus.