for some reason, my light plane does not lighten surrounding objects

I’m using cycles, I have a single light plane and it illuminates the birdge, but it does not illuminate the grass around it.

If I put another plane to light the grass, i have to set it to such a high level, that it washes out the bridge.

How can I have the same plane that is lighting the bridge, also illuminate the grass? The grass texture itself is not dark.

make the plane bigger?

Place emission plain far from bridge, increase light proportionally.

I ended up using hdr lighting and got good results, but I tried moving the plane and resizing it. I found out, that if I go to the uv unwrap and move the unwrap plane off screen to the right of the texture, it gets brighter. I don’t fully understand how that works, but I think it’s reading the image information slightly different?

Here is what it looks like with hdri -