Phoenix, Ariz., is in USDA Hardiness Zone 9. As such, many tropical plants will do well in the area. Many tropical plants require a lot of moisture, and because the Phoenix area can be very dry, tropicals will most likely require frequent watering. With adequate water, however, many tropical plants can thrive in the Phoenix area. All of these plants do best in fertile, loamy soil that drains very well. Phoenix soils often are very hard clay. Add about 20 percent compost with between 15 and 30 percent sand to encourage drainage around your tropicals. As you add sand, you may find that you need to water more frequently.
Belgian Hybrid Orange Bush Lily
The Belgian Hybrid Orange Bush Lily should grow well in Phoenix as long as it is watered frequently. This plant is recommended for zones 9 though 11. This lily can be damaged by the harsh sun in Phoenix. Grow this lily in the shade under an awning or taller plant. It is a perennial evergreen that has dark green, strap-like leaves and clusters of up to 60 orange flowers in the spring. The Belgian Hybrid Orange Bush Lily grows 18 to 24 inches high and wide, and generally doesn't require pruning.
The Bluebell Fern
Bluebell ferns grow in zones 9 and 10. They need plenty of water in the dry, Phoenix climate. This fern has shorter fronds than more common ferns, such as the Boston Fern. It grows best in filtered sun and may not get enough light when grown deep inside a room. Outdoors, grow this fern under a tree or bush to allow for mottled sunlight. This fern will do well outside as long as the temperatures don't drop below freezing. The Bluebell Fern grows to between 12 and 24 inches high and wide, and doesn't require pruning.
Purple Sheep's Burr
The Purple Sheep's Burr is a perennial that will do well in Phoenix. This plant has leaves that can reach 3 inches across and are made up of 10 to 15 small, olive green leaflets. This 3-inch tall tropical tree produces numerous 3/4-inch flowers. An easy to grow tropical, this plant grows very slowly and needs to be pruned only once every five years or so. It is a relatively small plant, growing to only 1 to 3 feet in diameter, and it needs full sun to thrive. Although it doesn't require a lot of water, it probably will need extra water in the dry Phoenix climate.