"Donna UK" wrote
Thank you for that Nick, will hold off on watering it until it warms up.
Roll on the warmer weather

Too much water is usually the reason citrus have problems which is why it's
best to never leave water in a water tray, in fact I don't use water trays
with citrus for that very reason. That said, I have had a small seedling
tree lose it's leaves this winter because I missed watering it.
Yours is probably too warm as well, ours are in our unheated garage (with
clear plastic roof) so only frost free. Our citrus are now coming into
flower and I will soon move them outside against a S. facing wall once the
worst of the frost has finished.
Next winter try it right next to a N. facing window in the coldest room in
the house and move it outside for the summer only bringing it back inside if
frost is forecast. Ours are usually outside from March to October.
Citrus, like most Bonsai, are not houseplants.

--
Regards
Bob Hobden