Michelle, my Frederic Mistral is grafted - I just buried the graft 3" below soil level and it's done great for 3 years. Yours' should too. I do have to cut it back above the snowline and winter mulch line, but it springs back quickly.

From a warmer zone, I do have experience with both. Three grafted do well. The fourth one is technically illegal because a big cane got broken and laid on the ground while still attached to its parent ...and it rooted and made a big wonderful rose the size of its parent. I never separated the baby from its parent. To try to keep things legal, I would say that the original connection still exists under the mulch.
But .... this happened in my acidic red clay. So I'd wonder if FM prefers soils a big on the acidic side of pH 7.0 and yours in the probably alkalin conditions of much of Colorado will stay grafted and not go ownroot.
Just a thought.

Thanks for the info. Good thing I didn't pitch the grafted one. :-)

MG, now that you mention it, some of the Candian bred roses really don't seem to get going on their own roots (notably Quadra and Capn Sam). The Mordens do well, though. I wonder if there is a preference for more acidic soil. Guess I could add some sulfur around them to see if they grow better (if not, they are rose-toast).

Cheers,
Michelle

I got my Frederic Mistral own root from Roses Unlimited a few years ago. It is very vigorous and survived the winter without protection; there was a lot of dieback but it bounces back nicely. I have had a lot of own root roses that died but Frederic Mistral does very well.