Cyathea dealbata [silver tree fern] is this the plant you mean? if not can you add a picture so we know what the plant is? :o)

When you say silver fern I presume you mean Japanese painted fern (athyrium niponicum var. pictum). Hardy, but will die down each year. In very frost ptone areas mulch the crown with something light (like woodchip or bark) over winter, but remove that by the end of Feb. Failing the protection, grow it under a tree canopy where it will receive a degree of frost protection

it'll be interesting to see which plant it is. I'd not thought of it being a painted fern. Friends have the silver tree fern but they do live in NZ.