Laterite, or gravel or sand or whatever, is just inert matter of varying grain size. It gathers and holds nutrients provided by the tank livestock--decayed uneaten food, or food eaten and processed into poo--and that provides the nutrients crispino refers to. If there are no, or not enough, occupants you will need to supplement the plants "diet" with fertilizers of some sort.
Root tabs are probably best at least at first; it's all prepackaged in a little disc and you stick it in the substrate, end of story for 3 months or so while they break down and release their elements. The package will give you directions for how many depending on size of tank. After that the plants should have their own life cycle going on and will grow (taking up nutrients) and then age and die (releasing nutrients). But what substrate to use--if any--is pretty much up to you based on how you want the tank to look.
People have grown plants successfully in bare bottom tanks, using cups or plant holders for just enough dirt/substrate for that particular plant, or even (shudder) clown puke gravel, so there is clearly a wide range of options available. Laterite is, as I understand it, basically clay, but the grain size provides a good base for plant roots to grow in. Good lighting is of course a factor in plant success as well. Best of luck....
