questions: query regarding how and when to use the npk 19:19:19 folier spray. 
 answers:  if you have use the fertilizer doses during the time of final land preparation then no need to apply npk now. you can use it when your plants attain 30 days then you can use it as a foliar spray 10 gram/liter of water 2 times, once in a week in the evening time in the absence of rain.