From ehow.com:

Lemon grass is native to South and Southeast Asia and Australia. It is grown commercially in India and the United States and is familiar to American palates because of its use in Indian, Thai and Vietnamese cooking. While lemon grass thrives in American gardens during the summer, it will only overwinter where temperatures remain above 25 degrees Fahrenheit all year.

Read more: Does Lemon Grass Come Back Every Year? : eHow.com http://www.ehow.com/info_8475165_lemon-grass-come-back-year.html#ixzz2Sj6HqV9z

I have grown lemongrass for the last 4 years, in zones 8(GA and WA) but it did not return.

But it is easy to grow it by rooting store bought . Just cut out top half(use it as you wish) and put tha bottom half in a glass half filled with water and keep it some where in you kitchen with indirect light.
Once it is rooted, plant it in your garden. You can buy a bunch of them from any Asian market for about a buck.

Never bother starting from seeds that might take for ever.

I have the same question! My lemon grass is cut all the way back and hasn't grown yet, but it has an awesome root system so I haven't given up.

well, if you know its root system is alive, just leave it. see what happens

Where in Zone 8 are you located ?

This post was edited by seysonn on Thu, May 23, 13 at 3:02

Oregon, about an hour from Portland. After a few weeks of 85 degree cloudless sky to start off our spring, there are now parts of Oregon with freshly fallen snow... so it's hard for me to keep from worrying about my new plants. I'm sure you can relate in Washington!

Well, we in Washington, Seattle area had a week or so of summer like weather. But then it got cold and nasty. We have been seeing night lows of 40 to 45 and day highs of 53 to 60F, mostly cloudy and damp.

The long term forecast, also not very promising, but shows some improvement on low temperatures side getting closer to 50F, which can help tomatoes, peppers, cukes..etc to start growing again.

Yeah, that's about what we're going through down here. It doesn't help that I'm new to having my own garden. It's only been a few years that I've had the opportunity and I may be giving my plants a little too much love for fear of losing all that time and money.