How might i improve translucency?

I am looking for a way to improve translucency/sss for foliage shaders
The main problem: their isn’t enough translucency going on; This is because translucency isn’t active on shadowed areas of the tree. This is the basic shader setup


In real life translucency is applied to all the leaves of a tree unless the leaf is shadowed very heavily/very dark shadowing, this is caused by the bright ambient skylight on a sunny day.
sss problem.JPG

If you look at the result, you can see there is no translucency/sss in the shadowed areas of the tree, only the leaves in direct sunlight have translucency. This is a big problem if you are creating a forest with a dense canopy because the almost all the visible canopy will be shadowed.

Can anyone help me improve it?

edit: nice sss here, But its not a good example because there is no bright ambient sky-lighting