How to create realistic leaf or grass material?
- Use curved geometry for leaves and grass blades instead of flat planes so it can reflect light naturally
- Use textures instead of flat colors for diffuse and translucency
- Use translucency, but not too much (usually fraction value at about 0,1 - 0,3)
- Put diffuse texture into translucency slot and tweak its appearance using Color Correction map (for example make it slightly more yellowish)
- Use high reflectivity but low Fresnel IOR value (Fresnel IOR at about 1,3 usually works well)
- Tweak glossiness value until the material looks realistic and doesn't produce visual artefacts (See: I can see bright pixels in grass!)
- Interactive rendering is very helpful when tweaking parameters of materials (See: How to use interactive rendering?)
- Do not use subsurface scattering for objects with no thickness. For grass / leaves it is best to use translucency.
See: How to use subsurface scattering? - Do not use refraction for leaves/grass materials - use translucency.
You can also download free high-quality material sets from the resources section on our website. "Basic Set" by Ludvík Koutný contains an example grass material.
Examples
Example grass material setup:

Result:

Example leaf material setup:

Result:
