We have a few lemon trees here in Germany, but every winter (now again soon) we have to bring them inside, because outside it is too cold for them here. I guess I can tell you only things you know already anyway: these plants grow best in a warm and sunny environment. The soil shouldn't become too wet (but also not really dry), and is preferred not to be too dense (you can mix the earth with expanded clay or small stones for a better drainage). If you want to make it perfect the soil should contain humus-rich garden soil, compost and peat (a third of everything).

I like these trees because the flowers really scent fantastic.