Thank you again for very usefull informations!
I'll give it some time before I fertilize the soil. But it's quite amazing, that even if there, in middle Europe is almost winter, it grows well, also developing new branches.
I looked on the tree thoroughly and I must admit, that the black spot problem isn't as bad as I thought.
I heard about the problems with toxic chemicals & fukien trees before. So, when I saw a little caterpillar about one week ago, I searched this forum and found some informations about "garlic tea", which was really effective and caterpillar is now gone
I hope I'll be one of those people having fukien nice & healthy
And there are pictures I've taken today, where you can see the difference...
