This poor clump of lemongrass has been pruned, dug up, split, left above ground for a few days then transplanted into bad soil in almost full shade. I expect it to survive. Can you kill these things with anything less than napalm?
This critter sprung up in a garden bed (where the strawberries are now) next to an existing clump of lemongrass. No doubt it self seeded. Wanting to reclaim some of the beds, we rooted out this guy and gave a huge hunk to Deb & Chris. Eventually we thought we’d try growing it in a dead spot along the fence. If this beast actually does survive, its parent will be rooted out and chucked so I can have its garden bed back. The thing is monstorous.
Besides cooking with lemongrass, I’ve cut a bunch of the stems full of seeds and some of the long grass and it’s now sitting on my chest of drawers in my bedroom. The perfume died almost instantly but it’s still a nice looking display since the bedroom is too dark to take living plants.
Update 4 May 2011: This lemongrass and it’s sibling are doing well. Not huge amounts of new growth but I’m sure it will appear next spring.
Laura Rittenhouse's Gardening Journal 
Very good stuff.
I had 4 lemongrass plants and they were HUGE!!!! (over 5 feet tall and 4 feet wide)
I believed you that they don’t make it in cold weather so I cut them back or dug them out after our first freeze. They did, however, look much better even then than your plant here does!
This one was HUGE itself before we hacked it to bits and set it out in the sun for a couple days before replanting. I’ve no doubt it will recover and be beautiful all year round. It seems to love the Sydney climate.