That variety is considered an annual ( 1 year only ) in cold weather areas. Turning brown would be a result of cold weather. In Marin, it may or may not come back from winter cold, depending on how cold you got. But if it didn't get any colder than around 28*F to 32*F it should green up this spring.

However, the other bad news is that even if it can survive your winter temps, it's not a long lived plant anyway. If you get 4-5 years you would be doing good. Sorry about that, they look really good where they are.

If they don't make it, I'd try another more winter hardy variety of Carex.

I'm sorry to disagree but New Zealand hair sedge - Carex comans (now known as Carex albula) - is NOT an annual, certainly not in most parts of CA!! It tolerates winter temps as low as 0F!! It is rated fully hardy to zone 7 and some sites will even list as hardy to zone 6 or 5b. Heck, they grow this plant in Ohio!

Like a number of sedges originating from NZ, it prefers cool (not cold) growing conditions and evenly and consistently moist soil. It will even grow in periodic standing water. The brown appearance is more likely due to lack of soil moisture than it is due to cold!! While it is not a common practice for most evergreens sedges and other evergreen grass-like plants, you could cut it back now and see how well it regenerates. I have done that before with this plant and it responded just fine. But if the brown coloring is due to lack of water and not just a seasonal appearance - it can often "brown out" in colder areas in winter - the plant may be too far gone to regrow properly and then should be replaced.

I am a novice when it comes to this plant. I have not heard it described as an annual before, but what do I know. I also live about 2 miles from the coast, it is quite mild (and damp) here, and at least other varieties of Carex thrive in the neighborhood (as this one did for 1.5 years, until recently).

I don't think it could be to to lack of moisture. It was drip irrigated quite regularly through the whole summer and indian summer, right up until rainy season, and it never showed any signs of brown in that period. We had a very wet December which was when it really started to brown out. Although we had some cold spells, it only got below freezing for a couple of nights.

Yesterday a gardener thought because it was slowly working it's way through, it was a fungus issue. Possibly due to rodent poison. I have no experience with mold/fungus, but this at least makes some sense in terms of how it has progressed. Seems as plausible as anything else I have heard.

gardengal48, if you read my comment carefully you'd see I said it's an annual in "Cold" climates. Which does not include CA. In areas where it gets below 0*F it will be an annual. Many areas of the country have winters way below 0. It is listed as an annual in cold winter areas, perennial in mild climates, by many nursery sellers, I didn't make that up.

In Marin it should be fine, but they will often turn tan during cold weather. If that's the case it should start greening up soon.

If it's a fungal issue, than they will have to be replaced. Pretty sure rodent poison doesn't do anything to plants, but I could be wrong.

If I were you I'd trim back some of the brown leaves down to the ground at the edge of one plant just to check if you see any new growth starting.