Why Won't This Sugarcane Grow?
It seems that you may be dealing with an instance where the server staff has nerfed sugarcane's growth rate, most likely using a plugin, or the built-in feature of spigot.
This is often done to prevent the price of easily-farm-able goods, like sugarcane, from dropping to rock bottom, or, in the event of a server store, people getting too rich.
Ask the server staff about this, and maybe they will give you some hints for their specific implementation.