Ruben Guzman was our guest for the June BSSF general meeting. Ruben was invited to the Hall of Flowers to share his experience about growing Satsuki azaleas for bonsai.

The techniques to train Satsuki azaleas for bonsai are very different from raising pine or maple trees. First, azaleas are shrubs, not trees. Trees are top dominant and shrubs are laterally dominant. This means that the weakest growth of an azalea occurs at the top and the strongest growth is to the base and lateral branches of the plant. When pruning or developing a young azalea for bonsai, you must remove vigorous lateral growth to promote apical growth.

Potting: The seasonal cycle of a Satsuki azalea in the Bay Area occurs in March with repotting. Ruben repots his bonsai around the middle of March (St. Patrick’s Day), the time of the year when a tree is beginning to awaken from winter dormancy. At this time, trees are experiencing a growth spurt and will be producing new roots and sprouts. Some literature suggests repotting in the early summer after blooming, but Ruben suggests otherwise. Mainly because plant growth is slower during the early summer and the plant may not recover quickly. In high heat, low humidity areas (such as Ruben’s home in Danville), a soil mixture of red lava, pumice and sand is supplemented with organic material such as peat moss and fir bark to increase water retention. This potting mix is not recommended for San Francisco residents where our humidity is high but lacks the heat. Ruben suggested planting trees in pure pumice or kanuma (a Japanese-imported pumice). While Satsuki azaleas need plenty of water, plants will suffer if their roots are continually soggy. Typically, azaleas are repotted approximately every three years.

Blooming: Satsuki azaleas bloom in late May or June. In fact, in Japan, Satsuki azaleas are known as fifth moon azaleas. Ruben notes that blooming is temperature dependent and during warmer years such as this one, his azaleas bloomed a few weeks earlier than normal. Satsuki azaleas are grown and prized for their blooms, which range in many shades and combinations of red, pink, purple, orange, and white. In fact, a single plant may display many different color patterns due to chromosome instability. Flower shape and size also vary widely. Petals may be long and tubular, wide and round, or even star-shaped. As the flowers fade, the petals are carefully removed leaving the stamens, pistol, and ovary. Once flowering is finished, all flower parts are removed. According to Ruben, removing the entire flower during the blooming phase may cause the plant to flower unevenly the following year.

Pruning: Satsuki azaleas are prolific growers. Plants readily bud from old wood and the base of the tree. All growth is removed from the base of the tree as it forms. After blooming, all growth is removed at the branch points except two sprouts. Choosing which new sprout will remain is simple. Strong growth is always removed to keep the internodes short. Sprouts growing back into the tree or growing straight down or up are removed. The overall shape of the branch is also considered when pruning branches. The ideal branching pattern of a tree is a pinnate form with a single primary branch, secondary branches, and finally tertiary twigs. This pruning should all be complete by the middle of July. At the beginning of November, another pruning and branch selection should occur. When larger branches are pruned from the plant, a ¼” - ½” stub should remain. This small branch will die and can be removed. Flush cuts are not recommended because the trunks are easily scarred.
Wiring: Azaleas can be wired at any time. Great care should be taken when wiring azaleas. Only softer aluminum wire should be used. Some growers recommend wrapping the wire in tissue paper as an added precaution. Azalea branches are very prone to scarring and are brittle.

Fertilizer: For proper development of azaleas into bonsai, they must be fertilized regularly. Ruben uses 1 tsp/gallon of general-purpose liquid Miracle Grow. Other popular fertilizers specific for Azaleas, rhododendrons, and evergreens are recommend as well. Ruben fertilizes his trees every two weeks except for the two hottest and two coldest months of the years. For Ruben, those months are July-August and December and January. When fertilizing your trees, you should note the color of the leaves. If outer edgeof the leaves are turning dark to black, you are using too much fertilizer.

Lighting: Azaleas prefer strong filtered light. Ruben grows his plants under 50% shade cloth. Other resources state either indirect light or a few hours of late afternoon/early morning direct lighting. If a tree does not receive sufficient light during the year, it will not flower. Also note that plants should be protected from high winds that may dry-out foliage.

Cuttings: The best technique for propagating azaleas is from cuttings. Azaleas grow easily from a short 2-3” sprout where most of the leaves are removed. A bit of rooting hormone is suggested. Cuttings are placed in mixture of 50% peat moss and #3 sand. Prior to mixing, the peat moss hydrated. Cuttings should remain moist and protected from direct sunlight under plastic.

Plenty of resources exist in the Bay Area for learning how to grow azaleas as bonsai. The local azalea bonsai club, Bay Area Aioko Kai, meets on the fourth Thursday of the month (except July, August, December, January). You can also read about azalea bonsai in a book written by local bonsai artist Robert Callaham Satsuki Azaleas for bonsai and azalea enthusiasts. El Dorado Bonsai in Placerville, CA offers specialized course in azalea bonsai culture. Contact them at (530)295-0200 for more information.

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