NABF Newsletter #8

Feature #14

Ironwoods (Casuarina equisetifolia) in Hawaii

By Lance Laney
Hanalei, Hawaii

The Casuarina equisetifolia, more commonly called ironwood or Australian pine, was imported to Hawaii from Australia in the late 1800’s. The ironwood is a very hardy tree and was used in many different ways but the main uses were for firewood, building material, windbreaks or to control soil erosion. In an ideal environment, the ironwood can grow to 80 feet (25 m) in just ten to fifteen years. On the island of Kauai, these trees can be found along coastal areas, favoring salt air and brackish water. It is not unusual to find large ironwoods growing along the shoreline with its roots extending towards the ocean.

When the early Japanese immigrants came to Hawaii as sugar plantation laborers, they did not bring bonsai plant material with them. These issei [first generation Japanese immigrant] worked long hours in very difficult jobs planting and harvesting sugar cane. However, on their day off, those wishing to pursue bonsai went to forest areas to look for plant material that could be used for bonsai. The ironwood became a desired tree, as it resembled kuro-matsu [Japanese black pine], a familiar and favored tree that was left behind in Japan. These early pioneers of ironwood bonsai had a great influence on bonsai, as we know it in Hawaii today.

Noted Kauai bonsai master Masaki Teshima probably has the world’s largest nursery of collected ironwood bonsai. Teshima’s father was one of those pioneering issei whose interest in bonsai developed the use of ironwood for bonsai. This passion and knowledge was passed from father to son. Today, Masaki Teshima shares his extensive knowledge of bonsai and ironwood with all bonsai lovers who have been fortunate to meet him and his wife Lillian.

On the island of Oahu, Edwin Nishida is noted for his effort in collecting and developing ironwood bonsai. One of Nishida’s ironwood bonsai can be found in the National Collections of North American Bonsai at the National Bonsai & Penjing Museum in Washington D.C.

These hardy conifers can be propagated in several different ways such as seed germination, hardwood cuttings, and air layering. As its name suggests, the ironwood is a very hard wood so cutting and air layering is best on half-hard wood. However, those of us living on the island of Kauai enjoy the challenge of finding and collecting an ironwood from the “wild”.

Ironwoods that are ideal for collecting are usually found in areas that are exposed to onshore ocean breezes, in poor soil with stressed water and wind conditions. Like the California juniper, the best-collected ironwood from these stressed conditions seemed to have good trunk movement. The idea is not to focus on the original branches. However, a good nebari and tachi-agari are a must. Like all yamadori, the tree must have some healthy small fine roots for a good chance of survival. As a rule, when I return home with collected ironwoods, I remove all the original soil and cut off all large roots that I will not be using in the future.

David Fukumoto, owner of Fuku-Bonsai Nursery on the island of Hawaii, has a very good technique for rooting yamadori ironwood. Fukumoto builds a framed box and covers it with clear poly-film. He places the newly collected tree inside of the box with a container of water. The tree sits in the box and literally sweats, producing new growth almost immediately. Ironwoods require lots of sun and fresh air.

Ironwood bonsai grow better in dry rather than wet conditions. I live on the windward, northshore of Kauai where it tends to rain a lot. I use a soil medium much like a kuro-matsu mix consisting of seventy five percent cinder and twenty five percent river sand. In drier conditions, growers use a much more organic soil with the cinders.

A collected ironwood with a good trunk and nabari will grow new branches very fast. It is not unusual for a collected ironwood to become a full mature bonsai in ten years. Ironwood bark can range from smooth, to flaky, or rough with holes, to nishiki [cork bark]. Finding a tree with nishiki bark is very rare and a very welcomed and lucky discovery.

When a newly collected ironwood starts to throw new leaves through its bark, then it is time to decide which of these leaves will be used for the new branches. Almost every new leaf that comes through the bark will mature into a branch. Like all true conifers, the ironwood has a seed cone. However, it is very rare for a potted ironwood to produce a seed cone.

In general, the ironwood is a very hardy and insect and fungus free. However, I find it necessary to spray several times a month during the spring and early summer with a systemic insect spray, as scales are a common problem with ironwoods.

Ironwoods respond well to fertilizers that are well balanced with trace elements. During the winter months, I use fish emulsion and in the spring and early summer, high nitrogen fertilizers. Miracle Growâ works very well.

Today on Kauai, finding good yamadori ironwood is becoming very difficult. Many good collecting areas have been sold off to off-island interests and KAPU (No Trespass) signs are now a common sight. Unfortunately, not understanding that ironwoods provide a good windbreak from stiff onshore ocean breezes and can help to prevent soil erosion, these trees are usually cut down and removed to open up the ocean views for these new property owners.

A special mahalo (thank you) to Masaki Teshima who shared his family’s history as well as his bonsai knowledge with me.