I've never had any luck overwintering Pampas Grass, but then again, I only tried the one time.

Check out the Far North Forum, Sierra has started some from seed. Perhaps she can give you some details how to overwinter it.

Sharon

Here is a link that might be useful: Far North Gardening

Pampass is an evergreen grass that takes a long time to produce the plumes. I have one here in Victoria from the previous owner of the garden. It takes drought quite well but it starts in April and the plumes are ready in October. Snow can brake the plumes so gardeners in Vancouver might cut a few plumes for the indoors if a winter outflow is forecast. The plumes are often left for winter interest on this coast. Many gardeners in Victoria cut it a foot from the ground as spring arrives. It gets messy when as an old plant. Freezing the roots will nuke the plant so they are mostly seen at low elevations near the ocean. Deep soil is required to make the plant become tall. Deer resistant.

Cheers