I'd be wary of buying seeds claiming to be lemongrass. I've grown lemongrass here for years and never seen a flower, either. If you pull a few stems c/w roots once frost is threatening, just pot them up and take indoors. It will overwinter very nicely. Should be a nice foliage plant if you can keep it in a sunny window.
Thanks for reminding me, my garden helper mistakenly yanked out the lemongrass, and I do need to replace my clump.
