Laurus nobilis (Laakeripuu)

I have had this noble and spicy tree in my green house for years. The only problem with is have been the aphids which paint the leaves black but doesn't kill the tree. 2018 I got some seeds and seedlings from my Italian relatives, all of then began to grow. I planted everything outside and most of the small the small trees survived the first winter though it was at least -20 degrees C frost. They lost most of their leaves, but grew a new ones in the spring as we may see on the photo. The next winter was not that lucky, so may be it is better to keep Laurus just in the green house.