Add some non chemical fertilzer, a 5-5-5 should be about as high as you would want to go. Yes, remove any flowers. To encourage more rooting, add a bit of bone meal too.

I grow it as a summer annual and find that light shade increases the spread of the plant. I would remove the flowers. Some where I have read that the plant may die after producing flowers. It sounds like you have a clump of plants so probably not a problem. The flowers should be wonderful tossed in a chicken salad.

My cats eat the plant to a nub when I bring it in the house. For an animal that supposedly hates citrus they really enjoy it.

Lemongrass prefers heat and humidity. It will sort of just sit and sulk until it really warms up. I keep some in my greenhouse and it stays alive but doesn't thrive since the temperature is set between 50 and 60 degrees. In Northern Virginia, lemongrass doesn't really get going until June.
There are two type commonly grown. The one that forms thick stalks and used in Asian cooking grows 3 to 4 feet tall and quickly forms a large clump in a single growing season (Cymbopogon citratus). It may or may not form flowers but is not typically grown from seed so flowers may be sterile. It has never flowered for me-frost kills first.
The other species Cymbopogon flexuosus can be grown from seed, is smaller, does not form as thick a stalk. It is commonly used in tea. My dog likes to chew leaves of this one-I have to watch him when he is in the greenhouse with me so he doesn't get into it too much!

I grow lemongrass in full sun and it seems to love it! When dormant or semi-dormant keep slightly moist and don't fertilize. Once growing begins, don't let it dry out and fertilize periodically, especially in lean soil.

I would give it a dose of fish/seaweed emulsion after the weather warms up. Also, make sure you have it planted in a sunny, well-drained location. And make sure it is well mulched.

I grow both the Cymbopogon citratus Lemon Grass and the C. flexuosus East Indian Lemon Grass here in south Texas zone 9a as year-round clumps of "grasses". Mine grow to about 4 to 5' and put out flowers every fall. I have never cut the flowers, and they keep growing. I have a large yard, and I have two planted up against the fence that have been there for about 12 years. I have others planted throughout my yard, and I also have several growing in pots in my greenhouse.

The East Indian Lemon Grass is a smaller form of the C. citratus with the same usage and cultural practices. And it makes for a better container plant because of its smaller size, i.e. about 18" to 20".

It is a frost tender perennial that can withstand temperatures of 10° to 20° with very heavy mulching, and it can be grown in the ground or in containers. In fact, it makes for a very good container plant. Plant it in full sun with excellent drainage. It can be cut back during early winter, but be sure to mulch heavily. It is thought to be native to India/Tropical Asia. It is a clumping fountain grass which grows to 3 to 5Â. They say flowering is rare, but I know that all of mine flower every year. It likes moist, well-drained soil and prefers full sun, but it can take some dapple sunlight. The blades are sharp so be careful, and always rub upward and not downward.

Here is an article from The Herb Companion about lemon grass.

I'm hoping someone can tell me how to handle a lemongrass plant that I have not cut back. I dug it last fall and it's wintered over fine, but now there is a combination of green and brown leaves. Can I cut the whole thing back now? Or should I just cut out the brown leaves. I've since learned that I should have done this much earlier. :)

Pam

Cut it right back so that it stands only about 30cm tall. As with any grass, you cut it, it grows, you cut it, it grows......

Don't want to waste all those leaves? Tie a handful-sized bundle with string or ribbon, and put a bundle in the bath. After a long day digging ditches, there's nothing better to soothe those aching muscles. Fresh is best, but you can always freeze the bundles.

Thank you, daisyduckworth!
Very logical and I appreciate your advice. Will do!
Pam

Questions:

I read that if you buy some stalks from Asian market with some roots and root them(more new roots) can plant them in the garden:
Here are my questions:
1- When to plant them (temperature wise )
2- how fast one stalk will increase to several?
3- When planting, how tall the rooted stalk shoud be ?
4- How often can you cut them back in one seazon . I live in zone 8 georgia.

Thanks

Cyrus, I plant them when I plant basil (soil is warmed up) and I plant two or three stalks together--they increase to a huge clump by the end of the summer. I just root the stalks I buy in Chinatown (actually, they are easy to find in many supermarkets, but often fresher in the Asian groceries) in a glass of water, then plant them. To harvest, separate the stalks from the clump at the base, or to harvest leaves, just trim then. You can do this anytime growth seems well under way.

Thanks coing

I bough some from Asian market here and I am rooting them.

But the thing is that it came wrapped in clear wrap, and didn't look fresh at all.
Anytway, I cut little bit from the bottom and put it in water. I will plant them when I see some roots.

Probably I will plant it in a pot so that I an bring it in in the winter.