I've bought a Christmas decor european tree from the store (please see the picture in the attachment), I read the instruction carefully but have no idea about watering the tree. The instruction only said "keep moist", but what's the meaning of "keep moist"? What about the amount of water I need to give the tree and how about the frequency? BTW, the instruction said I need to transplant the tree to larger pot after holidays, does it mean it can't grow in the small pot? Thank you very much!