how do I make grass look wet
I have tried using reflective shader but it bumps up the render time from 8 min to 8 hrs for a med quality crop render of 600 x 450
You could use a default shader instead of using a reflective shader.
Adjust the diffuse color to the desired grass-color, then go to the specularity/reflectivity tab (don't know exactly the right name by head). Choose a reflectivity of 0,25 or so with a specularity roughness of 0,5 (lower roughness gives very localised bright highlights, higher roughness gives more uniform less bright highlights....you should play with these values of course). Hope this is of any use.
Martin