Ideas for a tropical garden with dry,unfertile soil ?

I am from Sri Lanka which is a tropical country. There is a patch in my garden with unfertile & dry soil. It is very shady so I tried growing foliage plants. They have grown but still the soil is not rich enough. Could you give me some ideas as to what to do with it.

You need to improve the soil. You can do this by adding some mulch and turning it into the soil. Try planting bromeliads, crotons or cordylines. They are colorful foliage plants and I am sure they will be available there. Water and fertilise regularly for success. Good luck.