That stuff is no good at all. You need to make sure your compost/soil is ericaceous first - for acid loving plants. Put it back in it`s pot - not a bigger one, and preferably the pot is best if it`s the old fashioned clay type.
Your lemon needs open free draining compost to allow the roots to breathe. I suggest mixing in some orchid compost , which is composted bark with perlite. When it`s in the right stuff, water it from the bottom. Put some warm water in a bowl and stand your pot in it for 5 to 10 minutes. This allows the water to be taken up where it is needed. Don`t get the stem wet above the compost level. With this method you need to water thoroughly to start with, and then keep the plant light and warm and don`t water again until it`s very dry. Feed with liquid seaweed, and follow the instructions to the letter. Over feeding never helps. Good luck, let us know how it goes.