Hi Terri!
Thanks for the quick reply
I just come back from the book store and I found that the spots were sunburns too
Thanks for the other information too.
One last question: is it better suited for a pot (I re-potted it in a cedar basket when I got it) with a mixture of cedar shaving and perlite; or mounted on a bark plate?
Otherwise I have more or less the same setting than you have: south windows, additional T5 bulb (6400k with 2500 lumens) (necessary because we only got 4 days of sun in July, and there are some trees adding shades). Otherwise they are mounted on a cedar rack (built like the generic cedar mounts that let air flowing through all shelves.) and a lot of air circulation that come from a vent of the forced air system of the house (directly under the shelves).
Take care