Drake Fertilizer  

 

I had the same in this instance. One instance the kirin with the fertilizer popped instantly on the death of the goblin. The one variable in this instance that maybe someone else can confirm was that in the course of randomly killing we got a drop of "fertilizer" from a random goblin prior to killing the pot goblin. Perhaps given the text of the task(find the right fertilizer/materials to keep the dark lady alive) it is necessary to find the "wrong" one first randomly. Other than this variable, the 2nd instance the Kirin never spawned in the same length of time with a higher number of mobs killed than the first. Hopefully this will prove helpful in figuring out the other piece or pieces that trigger the kirin other than killing the Goblin Gardner.