High nitrogen feed - if you were in Britain, I'd suggest something like Baby Bio or Phostrogen, both of which are mixed with water and applied when watering. We also have something called Growmore, which is a granular form of high nitrogen feed - that can be stirred into the top of the compost and then the plant watered as normal - this form of feed takes up to six weeks to break down completely, so won't need reapplying often. All these feeds contain other nutrients as well, not just nitrogen.