I have a mandarin I bought 2 years ago that was living in a pot until this month. It wasn't really happy in the pot (slow/no growth, no fruit, sort of dull leaves) so I put it in the ground. It's tricky ground, heavy clay and alkaline, so I elevated it and planted it basically above ground in a hill

with a good soil mix for drainage etc. and well covered in mulch. I know it's not perfect, but it's what I'm working with. Right off the bat it started seeming healthier with tons of flowers and the leaves seemed ok. No noticeable problems anyway. Then I think I watered it too often--every couple of days, like you would most other transplants. I didn't think that through. Anyway, now the leaves are suddenly looking rough. New growth is healthy, but the full sized leaves are yellowing. I've read that may mean the plant is sucking Nitrogen from the older leaves to give to the new leaves. My question is, how do I add Nitrogen now since I've already watered too much. Better to wait for it to dry out or better to give Nitrogen right away?

That last picture is of the healthy new growth. I know it looks yellowish in the pic but it's actually a nice normal young green. I appreciate any help on this. (Sorry for the sideways pics. I don't know why...)

Amanda