We can calculate the implied growth rate of dividends if we know the value of the other 3 variables in the GGM.
where:
V0 = fundamental value
D0 = dividend just paid
D1 = dividends expected to be received at end of Year 1
r = required return on equity
g = dividend growth rate
As long as we have 3 known variables, we can back out the 4th using algebra.