I planted three Nova Zemblums from the local nursery this summer and one by one each died. I pulled out my last one out today. I noticed the soil was very dense clay and have really worked the soil to loosen it up. I've also planted my replacements a little higher. I did notice that the root ball is wrapped extremely tight and my previous rhodos showed virtually no root growth. These rhodos were all container grown and extremely healthy looking at the local nursery. Do I need to do anything to the root ball and if so what ?
I would definitely loosen up the rootball. Otherwise, especially since you have clay soil, the roots are never going to grow out into the soil. Try digging it up, then soaking it really well in water, that should help make the roots easier to work with.
You may want to also regularly water them slowly and deeply every time that the soil feels almost dry to the touch at a depth of 4". The root ball drying out is a very common problem but slow steady watering for a long period of time will help prevent this. If you need some kind of reference, think drip irrigation and think leaving the drip on for an hour or hour and a half. Note: a drip irrigation hose is not the same as a soaker hose, which releases water faster and in more places than a drip hose. You can do this with a regular hose too as long as the water stream is kept small and you do not forget to shut it off after an hour or so. I set my oven timer sometimes for things like that.