Cocco coir is like hydroponics in that it is totally inert. Ph nutral and void of any nice goodies that helps new growers to forgive their mistakes. The plant only gets what you give it and if you get that wrong then you are fucked. Stick with soil my friend until you have cracked it and then move on to other methods. Stick with canna IMHO I learn't my shit with canna, can be a bit pricey but good results.
Good Luck
