Dunbartonshire,
United Kingdom 
my cortaderia selloana plant is three years old it hasnt had any feather type not sure if you call them flowers, what could be the problem
11 Sep, 2014
Previous question
As nobody answered I looked this up for you. It appears to take about five years to reach its ultimate size so perhaps its still too young? You could try asking the question again calling it Pampas Grass in case people have grown it without knowing the Latin name ( I didn't)
12 Sep, 2014