Stone retaining wall mortar mix lime ?

[Perki6]

Hi just want some opinions on a stone wall I am building in the front garden. I am getting a bit confused if I should be using lime in my mortar mix ? Its just going to be a flower bed on top . The wall will be 3ft high by 16inch wide
I am using 4.5 red builders sand to 1 cement which I think has been used on the other section of wall I am joining to, I 've put a weeping pipe in for drainage and will be back filling around the back of the wall with rubble to aid drainage . Stone is some Yorkshire stone I suspect which is a tad soft compared to the rock hard local stone.

Thanks