Hey guys!
How can I add some variation in the material’s base color that goes randomly on different actors?
In other words I would like to have the fir tree would a bit of variation in the green.
Take a look at this video:
https://youtube.com/watch?v=cp6JQVHWeEw 
You can find a setup for trees in this free vegetation pack: https://forums.unrealengine.com/showthread.php?59812-Free-Foliage-Starter-Kit
if you intend to use the foliage system the “perinstancerandom” node is an option as well. will give you a random value from 0-1 which you could tweak and use on a hueshift or something like that. might give you less control and no clustering compared to a projected texture but will also not produce any repetition whatsoever.