I recently purchased a stag horn fern that was potted. Once I got her home and wanted to begin transferring her onto a mount, I discovered that she had been potted with regular outdoor gardening soil. I just can't seem to get all of the soil out of the root ball. And in my process of trying to remove it all, I have accidentally broken some of her roots. I have now set her aside to ask how best to proceed before I cause any further damage! Please help!

The pot (6in.) pictured was completely packed with garden soil and rocks and roots, and then the other photo is where we are now.

Don't worry about it. Especially when mounted they can have a big wad of potting soil at the roots. Any broken ones won't matter, and with some good medium and good conditions they will quickly regenerate. When I mount them I use a huge half-moon shaped pad of potting soil, and huge amounts of long-fiber Sphagnum over it. You can use fishing line or fine plastic-coated wire to attach to the wood.
Have fun and don't fret.

I had one for many years. You can just wrap the messy ball with coconut fiber and hang the whole thing up with/on a chain. in no time flat you have a huge green ball with those long hanging fronds. In Winter mine hung in a corner in the house, Summer outside in a tree. it needs plenty of water!
Mine got so huge, I took a cutting with a saw, gave the mother plant away. That cutting looked like this a couple of years later. I gave it to a local flower shop. Here is the fellow carrying it to the car.


What I am trying to say is that they are very forgiving and somewhat indestructible, as long as they get watered enough.
Enjoy your plant!

Aidenc, Hortica is absolutely correct Staghorns grow the way they do so they can catch decaying plant material that falls off the host tree or rock for their own nurishment. A handfull of good potting soil stuffed into their root ball would be a welcome feast for your fern. If I might make a suggestion--if you can find cork bark to mount it on, you might find it easier than a plank, and it also generally will last much longer than a plank. The cork I am talking about is cut off the trees in sheets, can sometimes be found in lengths as long as 3 feet, and has a natural curl like it was growing on the tree when it was stripped off. Most people plant the staghorn on the outside of the curl, but I preferred to plant the fern inside the curl because the plant was easier to secure that way. Cork stands up under the almost always wet conditions produced by Staghorns much better than most wood. Good luck, Staghorns are wonderful long lived plants that really require little maintenance, and last a long time between mountings. It will eventually totally engulf its mount. Have fun Bill