Pampas usually waits for warm weather to start growing. It doesn't know from a calendar. I have one, grown 2 years ago from seed, and it just started showing signs of life this week. It's in a pot, buried in the ground. This will have been the second winter it survived. Mine is species Cortaderia selloana. If you have one of the more hardy cultivars, like 'Pumila' it should be good to zone 6. Most others are only hardy to 7.

did I do the right thing by cutting it back in mid april? I let it stay tall throughout the winter but then someone told me to cut them back in early Spring? Was that too late? It has been in the 60's here when should I start seeing it green up or new growth?

You can cut them back any time before the new growth gets taller than the cut-off height.

It's impossible to tell when your plant will start growing. Mine just started last week, and I'm in a fairly mild coastal zone 7. The new shoots are only 3" tall, and pretty sparse.

Give the plant a liberal dose of patience. ;>)

I am in the same boat. I bought pink pampass grass last year, and it grew pretty big, but never bloomed. I cut the dead foliage off about a month ago, and noticed that it looked pinkish red where i cut it off, so I assumed it was still alive. But no new growth yet, still have hope for it I would really like to see those pink plumes this year! I have read though that the pink version or the pampass grass is a lot more tender than the white kind. (Sorry, don't know all the scientific names!) It has been pretty warm here though for a couple of weeks. Do you think it will be OK? Ill keep my fingers crossed!