Of all the flowering bonsai, azalea bonsai are perhaps the best known. The Kurume and Satsuki hybrids (attributed to Japan) are the most popular of flowering Japanese bonsai. Botanically speaking, they are two sub-genera of Rhododendron (sometimes called Rhoddies.)
There are literally thousands of species. They range from low growing shrubs to tall (20 meters/ 60 feet) varieties. The colors and color combinations seem endless.
Although popular in most countries, tropical areas often have trouble growing many species of this plant as it is prone to fungus in hot climates.
Because of this problem, many tropical growers have made other choices for blooming plant varieties - favorites such as Bougainvillea.
(There are a few exceptions, see the Hawaiian exception below.) The rest of the world savors the wonderful varieties of shapes, sizes and flowers. Although they often have straight trunks and branches, when wired, they can be adapted to many styles.
Harry Harrington's very complete 'Calendar for Satsuki Azalea' page is highly recommended. Although Harry is in England, you will glean information on this species no matter where you live. As with any bonsai care instructions, always take your climate into consideration.
A source for good pruning information are two YouTube videos with Peter Warren, a well known professional bonsai talent.
In this video 'Satsuki Azalea Bonsai Exhibition at Ueno Park, Tokyo' there are no scrolls and relatively few accent plants. It's all about the flowers! (The display stands are impressive too.)
The age of this root-over-rock style is emphasized by a very old bonsai container.
Neagari is probably one the last styles you would think of for this species. However, when an exposed root opportunity presents itself, you may decide to create something like this beauty.
This grouping is another unusual style for this plant. The container is also unlikely for the species. The unique use of both adds to the beauty of this specimen.
The lava rock mountain, to the right, is planted with a small variety of azaleas. It was created by Hawaiian, David Fukumoto.
The variety, is uniquely suited to his very hot and humid, tropical environment. Even when not flowering, a well designed grouping can be quite beautiful.