Sadly I don't have access to a garden at the moment.
The bonsai appears to be fertilized so I'm not sure if I should add anything else to the mix. I guess I'll wait for a bit and see if there are any changes.
Thanks for the help guys. If anyone else has any other suggestions let me know.
I recently purchased a Sweet Plum and some of leaves are turning yellow. It seems that it's mainly the tips. Should I be concerned or is this fairly normal for a plant that's exposed to a new environment?