One more thing,maybe the soil you have has lot's of great stuff in it already! your soil it self may already be loaded with ferts,therefore by adding more chemical ferts may cause a bigger problem then just a little burn on the tip!,,,,,,but try it any ways unless your soil is super great!,but just try it if your plant starts to burn up after the second day just flush her with about 2 or 3 gallons of water which will clean out most of the chemical.....like I said most of growing pot is a hands on experience anyhow! I learned more on my own then from anyone helping me out,a couple of failures will lead you to some great victorys lol...but when growing marijuana who wants to fail? not me lol.