Thanks for the reply. I'm going to do some experimenting. I think it might mostly be the camera - as soon as I take the picture and look at it the greens already have that kind of plasticy fake look compared to the actual plant (so the pic I posted here isn't very useful!). Hopefully there are some good post-processing options in Photoshop to help correct this.
The DMP photography guide recommends just adjusting the exposure and temperature/tint, but it seems necessary to go beyond that.