Lemongrass grows just like any other grass. To propagate it, place the root end (after you’ve cut the rest off) in a glass jar with a little water, and leave it in a sunny position.
Within a week or so, new growth will start to appear. Transplant your lemongrass into a pot and leave it in a sunny outdoor position. You can harvest your lemongrass when the stalks reach around a foot tall – just cut off what you need and leave the plant to keep growing.