Which Plants Benefit From A Deeper Substrate

[Evad]

Most of my subtrate will be a mixture of eco-complete and gravel. And in most of the tank (180 gal) it will be 3" deep. I have some extra material so I am thinking about making the back corners of the tank 4" deep or more. What plants should be placed in the deep substrate? For example, I figure my swords should go in those places for sure. Are there any other plants that would definately benefit from 4" or deeper?

 

[Colin_T]

swords are about the only plants I can think of that have really big roots systems. Most plants will be fine in that amount of substrate but they don't need that much.
Hygrophillas have bigger root systems than Vallis and Ambulia but I would stick swords in the back corners.

 

[Themuleous]

Lotus plants have massive root systems.

Sam

 

[Esfa]

Lotus plants have massive root systems.

You got that right. When i took mine out, the roots were like a carpet, shaped to my tank.