" Tropical gardens can contain a wide variety of plants, but some require lots of heat while others require lots of water. Tropical gardens also don't often survive freezing temperatures either, so many people in cooler climates choose to create tropical container gardens which can be taken inside when bitter cold winter temperatures come around.
Most tropical plants require a lot of sunlight though, so if you're planting them into a ground based garden or raised garden bed, be sure to choose the sunniest spot you can find in your yard. You'll want to plant tropical plants and flowers in areas which get a minimum of six hours direct sunlight each day. Some tropical garden plants such as bougainvillea, thrive on irregular watering patterns"
Esperanza and Spanish Broom are excellent plants to put into a tropical garden, which are both heat and drought tolerant. These plants produce bright showy yellow flowers that bloom continuously from spring through fall.
http://weekendgardening.com/tropical-gardening/tropical-gardening.html
