Lighting issue: bright green grass in dark interior

I’m working on a dark cave interior, and for some reason the green grass and ivy’s (static meshes) ends up bright and shiny in the darkness after light baking.

I’m using the SM_Cave_Grass and Ivy from the Infinty Blade Grasslands set, and also a directional light with some point lights and a spotlight. Here’s some examples:

Probably this is a noob mistake, but I’ve googled around for a few hours and haven’t found out what’s wrong.

By disabling the directional light the ivy’s don’t shine like christmas trees anymore. I kind of believed that two-sided rock meshes would stop that directional light from penetrating through the cave shell, but apparantly not. The grass and ivy’s are still somewhat too bright compared to the rest of the meshes though.

It turned out the M_Cave_Grass material had an emissive colour. Unplugged the thing and now the grass is dark too, hip hip.