Hollyhocks are one of my favorites, and I much prefer the single flowers. It took me years to establish them, and I think it was because I have only recently started to feed my London clay soil with compost and mulch. Everything grows better now!
You might enjoy my photos: I tried to do the link below with a simple link, but it didn't work.....anyone know why?
Photos of Red Hollyhocks and Simple Photoshop Tips http://gloriousconfusion.hubpages.com/hub/red-hollyhocks