I hope this isn't a silly question but the rules are not specifically clear on this point:
When harvesting spices, does one have to take spices that the tile started with? Specifically, if you have empty spaces that were originally green/red, can only green/red spices be placed here? Or does the color only matter when the plantation/colony is originally founded?
The green/red can, obviously, only generate green and red. However, just because you placed, say, a green on the right the first time, you don't have to place a green on the right the second time: can place either green/red as needed.