Arizona's desert landscape is not nearly as lifeless as you might expect. The bright blooms contrast sharply with the desert backdrop to put on a spectacular show for passersby. Spring time is an especially good time to see a variety of wild flowers in the Arizona area.
State and national parks are great for wild flower viewing. Boyce Thompson Arboretum State Park is located about a one hour drive away from Phoenix. The area is open year round and during the spring they will often offer guided wildflower hikes free with your $7.50 admission to the park. When the wildflowers are blooming the park rangers will frequently post pictures of what is in bloom on their Rangercam web page.
The Desert Botanical Garden is another great place to see local flowers in bloom in the Phoenix and Scottsdale area. The Desert Botanical Garden is open daily and provides a variety of guided tours throughout the year. Their web page is also a great resource for Arizona wildflower information with maps to popular viewing locations and links to extensive photo galleries.
Saguaro National Park is great for viewing wildflowers in southern Arizona. It is located in the Tucson area and is open year round. The peak season for visitors to the park is in March when the spring flowers are blooming. April - May is when the cactus flowers are usually most in bloom and the summer flower season runs from June - September. This PDF file from the National Park Service lists the types of flowers and colors you can expect to see in each flowering season.