After months of waiting, my phal bellina has decided to produce a bud at the end of an existing spike. Think it either was resting from previous flowerings (can't take credits for those flowers.) or it wasn't getting enough sun until now. Now with a bud forming, i would need advice on the fert to use. I have 3 types and npk are as follows:

1) 15-45-15
2) 7-13-34
3) 21-21-21

Which one should i use? Thanks in advance.