A time to sow, a time to reap
But over a life, this time would creep
I was created in 46 B.C.
Brought into being by Caesar's decree
But still the seasons were unimpressed
Man-made and tropical slowly digressed
So good Pope Greg set everything straight
with inspired rules that worked out great
I am grander than my common peers
I come 97 times every 400 years
By following my rules, as widely agreed
We all know what day to plant our seed
What am I?