Soil Question: Ferns and Clay Soil

I got my first question from a blog viewer! It came from a Master Gardener..... (wonder if I'm being tested!). Here's the question:


"I am about to amend my clay soil driveway hillside with composted horse manure so that I can move ferns from elsewhere on my property into new holes. Ferns like lots of forest compost. I am leary of this introduction of very rich compost into holes dug in clay. How well with the ferns do? Will they do poorly once their little connecting roots hit the clay? I bet so. Thoughts?"

...... and here was my answer:
"I think you need to do more than just dig a hole and stick a dollop of composted manure in it. You need to condition the entire area where roots are likely to spread. Maybe add some sand to your amendment so that when all the manure breaks down you're not right back where you started with just clay and dying ferns, but you've begun to give your soil some texture so it can hold nutrients/air etc better over the long haul. I did some looking about in my gardening books and found a recommendation to also consider adding some gypsum, along with the sand, to help loosen up your clay soil.... it adds Ca and doesn't change the pH.
Manure raises N2 levels and lowers pH. Couldn't find out what makes ferns happy.... you know the answer to that one?"

Whatcha think? Would you have said something different? I'm open to feedback.... only way to really know if you've learned this stuff is to jump in and give it a go!