I have a 2.5 gallon tank. How many inches of sand should I put at the bottom to grow some Vallisneria Torti?

Vallisneria tortifolia or vallisneria corkscrew, there is a lot of diff names for the plant.

I have a 2.5 gallon tank. How many inches of sand should I put at the bottom to grow some Vallisneria Torti?
that's a tiny tank...maybe an inch