I could not get my toilet unstopped. I removed the toilet and found I had subtanial root growth where it had broken the flange that the toilet mounts too. How can I replace the mount flange? I put some root cristals in the pipe while I figured out the repair.

First off, if you have roots up to the closet bend you have a major root problem. Before you reset the toilet I would run a snake with 3" cutter blades dow the line and then flush out the roots. Next I would bust my tail to find the break in the line that let them in. You have options on the flange. You didn't say so I'm assuming that your flange is cast iron. To replace a cast iron flange you will have to have lead and oakum, yarning, packing and caulking tools, plus the knowledge to yarn, pour and caulk a joint. That's the hard way. Let me show you some easy ways. If just a slot's broken then a repair kit is needed. Check it out at http://www.plumbingrepairflanges.com/spanflg.htm
Here's another way. With a 1/4" masonry bit drill,( if cement floor, if wood use wood screws) two holes where the bolts go. Then using plastic inserts,( in cement floors) and wood screw closet bolts you can then remount the stool without a flange, (just leave the old flange there.). The wood screw closet bolts can be picked up at any plumbing store. Also purchase a new wax seal with a funnel to replace your old one. If you need more information, click on back. Regards, Tom

It looks pretty bad. The closet flange is stamped sheet metal attached to PVC. The roots have broken the flange away from the PVC and cracked the main line going into the ground. There is roots all the way around the outside of the main line where the closet flange was. I was in Lowe's today and found a cast iron closet flange that had a rubber gasket that fits the out side of the 4" main. Can I try to cut the main below the crack then chip the concrete so I can add a PVC adapter then put this new cast iron closet flange around the adapter? What do you suggest I do?

OK! Yes that would work if you have enough stock left on the PVC vertical raiser to slip the cast iron flange neoprene gasket over and make a water tight seal.
Call around to different plumbing shops or Rent All stores and ask them to rent you a set of 4" inside PVC cutters. This tool fits inside the pipe so you can get a straight cut without having to tear up your floor. you can then slide the neoprene gasket and the flange over the pipe and secure the flange to the cement floor with Tap-Cons or 1/4" screws and plastic inserts. Good luck, Tom

I could not get my toilet unstopped. I removed the toilet and found I had subtanial root growth where it had broken the flange that the toilet mounts too. How can I replace the mount flange? I put some root cristals in the pipe while I figured out the repair.
The broken flange is in a cast iron pipe in the cement floor