The reason not to fertilize in the fall is so plants don't put on extra new growth. A hardeming off needs to start occuring.

It sounds like what you're doing is likely the best, keep putting down organic matter to slowly feed the soil, and a good mulch goes a long way over the winter to keep the soil from drying out and can often keep the soil from freezing more than a few inches, if that. I don't see the point in adding fertilizer. much of the nitrogen would just leach away before spring.

Now I am hearing fertilize so they can get ready for winter.

Are you hearing this from someone who wants to sell you fertilizer?

I can't speak to a lot of perennials, only what I've learned for peonies (because you all know I'm the crazy peony lady) but it seems peony roots do benefit from the application of fertilizer in the fall before they completely go dormant. I never fertilized my peonies in the past since the beds I created were raised and filled with planter's mix. I saw so many other members on the peony forum post incredible pictures of first and second year plants that were on a fertilization regime that I'm giving it a try this year. I started early spring when I first saw the beginning of growth with an application of BulbTone, an organic bulb fertilizer, and azomite. Even with that one application I saw a remarkable difference in the size of the flowers on several of my established peonies! I'm not sure the azomite really helped though. It's stated purpose for peonies is to grow hardier stems--didn't see any improvement in that area but I'll still put it out this fall and early next spring with the BulbTone hoping that the continued use will get the results I want.