Friends who use the application (GrowDoc) tell me it gives out truthful information? And are there other similar apps for this?

Ummm interesting. I’m outta town but I’d love to see what it says for my plants.. I just can’t imagine it’s a hundred percent accurate.. but if they put the time in to coding it properly then it might be decent. Problem I see is that a deficiency can be the result of lack of nutrient or pH or other things. Same symptom may be caused by different things. So you still have to know why not just what