imo, i would grow the plant in a 20-30 gal hardside, in 50/50......of the same medium.....then transplant into the biggin' with 75% ss....right when she is full throttle in the smaller pot....i have seen trees in ss peter out during week 5-6, believe it or not, they will get such a huge root mass, it will suck the nutes up in the ss in a heartbeat.......esp. if you only has ss in the bottom...it is a real touchy deal dealing with growing trees in ss, or "no-jug" style....good luck!
p.s. i do outdo, in ss and smarties.....just not that big......