You doing a beardie or uro, I'm guessing?

In any event, though I had to burst your bubble, you are best off:

1) Make VERY sure that extra humidity and moisture will not be a hazard to your lizard. Many of the arid dwellers are prone to fungal infections if their home is not kept very dry -- and water draining into the soil will not dry out quickly.

2) Go with fake plants -- seriously. Attempting to keep live plants in with a herp is not an easy thing.
a) If you keep conditions sufficiently arid for the lizard, the plants will suffer/die because it will be far too dry for them unless you go with some of the cacti or succulents.
b) Cacti present obvious safety hazards (spines and some contain poisons) and many succulents contain compounds to make them unpalatable to animals.
c) Furthermore, giving plants the lighting they require for healthy growth is not easy (and in a vivarium is extremely problematic for cacti, many succulents and even other plants). Remember, just because the light seems bright enough for our eyes, that does not mean it is bright enough for the plants' needs.
d) In addition to all this, herps are notorious for digging plants up, knocking them over, or crushing/breaking the plants as they sit on them or run over them. (For the latter, think of how quickly grass in a lawn gets matted down and killed off when people or dogs repeatedly walk over it. It does not take long.)

Not trying to be a wet blanket, but while I understand your desire to design a neat, naturalistic set up, the reality is that it simply is not a practical idea.