A great many herbs are perennial - oregano, thyme, rosemary, tarragon, mint, lavender, chives, fennel etc. - and all will be fully winter hardy in a zone 8. Parsley is biennial and will need to be replanted every couple of years or when it goes to seed. Cilantro, dill and basil are annuals and must be replanted each year.

I grow cilantro and chervil during the winter in my vegetable garden. True , I cover them with a floating frost cover on the big freezes. They normally live through them but they seem to grow faster with the cover. It keeps them from going into a state of dormancy. I have the curry plant in a pot , but they say that is root hardy in the ground. I also have Kefir Lime in a pot, that I grow indoors during the winter. I have grown lemon grass outside in Austin and a friend of mine has it successfully growing out here west of town where it gets to 8a on some winters. I have killed mine when I have attempted it out here....I am trying again. I probably need to protect it the first few winters.. There is an Italian rustic arugula that is a perennial and takes the summer heat too. It get leggy in the summer and I cut it back. The leaves get small and have more of a bite. it is very drought tolerant.

The generic rosemarys from the big box nurseries haven't survived reliably for us in 8a. If in that zone or colder, might be worth looking for one of the hardy cultivars from late east Texas herbalist Madalene Hill. We have 'Hill Hardy' and 'Arp' is the other I'm aware of. Other hardy cultivars are available and worth considering, but the Hill varieties are probably the most commonly used... especially in Texas.

I'd have a hard time imagining any rosemary not being winter hardy in a z8 climate, provided it is planted in fast draining soil. We use the shrubs for hedging up here, they grow so prolifically!! Only the prostrate forms show some signs of cold damage in a rough winter, but that is easily pruned off - they are fully root hardy.

Gardengal48, Yes - believe north Texas clay is a factor in the demise of many of our zone-marginal plants. They can survive our low temps or our wet clay for several seasons... until just the right fatal freeze and moisture combo. We had a bad rosemary die-off in Dallas (8a) during winter 2013/2014 when it did not get exceptionally cold, but was extraordinarily wet. Here's how the National Arboretum sorts out hardy rosemary cultivars in zone 7.

standard rosemary has survived everything for 15 years) prostrate rosemary kicked the bucket this last freeze

My standard rosemary bush out front, fully exposed, survived our 19º freezing temps, as did my Italian oregano and onion chives left uncovered. My sweet basil was alive and healthy at the start of our freezing temps, and I harvested most of the leaves off of it to dry. It died off from the cold, but expected the "remainders" to die off. But basil doesn't ever live through winter and must be replanted annually.

My standard rosemary did not survive this last freeze, and neither did my mother's who lives ten minutes away. It was such a fast and severe drop in temp...I think we got down to 14 and more with the wind, and that was it.

My standard rosemary has gone completely gray with the freeze in December. My fingers are crossed that a trim will bring it back.

That's what I was wondering about my rosemary. It's never turned gray before, so my mother was telling me they're gone...I'm hoping it will come back though.

I guess it is a good time to plant another . I have lost mine from rotted roots and then a drought. Maybe the freeze was just the last bit of stress.