I think lily of the valley is a temperamental thing...it grows where IT wants to and when it chooses. It's devilishly difficult to start...it seems...and then devilishly difficult to erase. I now no longer want it..it trawls underground straying from where it once was. Ok, the question......will it grow in a pot? Not sure it will unless it's given adequate moisture without drying out and out of strong sun and if it as the will to grow in one. I will try it though when I dig up some of my clumps. Most of us struggle to grow lily of,the valley according to the info I read