Bonsai Studies in Japan: Part 3 by David Johnson Bonsai Containers The Bonsai Studies series continues with this article on bonsai containers. Its purpose is to relate important points that Mr. Nakamura made on this subject and is not intended to present a comprehensive explanation on pot selection. Container Size and Watering On my first day at Mr. Nakamura's Shonan School of Bonsai, I saw a semi-cascade Japanese white pine (pinus parviflora) that I had wired in 1999. In fact some of the wire I had put on that tree was still there, in addition to the large curved steel bar that was used to bend a large branch. It has been three growing seasons since this work was done. Mr. Nakamura had since repotted the tree into a larger pot. Mr. Nakamura said it needs an even larger pot to be able to provide enough water for that mass of foliage. He pointed out that there was a trend in bonsai to use larger pots to protect the health of the tree.

Pinus parviflora that needs a larger container to accommodate foliage mass.

In another example, Mr. Nakamura inspected a nicely shaped gingko and discovered that it was growing in garden soil covered by moss and weeds. The garden soil, which retains too much water, had led to root rot. Mr. Nakamura cut back the roots to white ends and then replanted it in a small growing pot. Mr. Nakamura said that a larger pot may suit the size of the tree but not its root mass (or lack of) and a larger pot could lead to even more root rot because the water in the large mass of saturated soil could not be soaked up by the roots. Mr. Nakamura changes the pot one size up at a time as the tree recovers. The gingko was placed in the greenhouse to help it recover. Mr. Nakamura repeated this point with the example of a Yokohama grower who had grafted 3,000 pine seedlings. When the pine grafts took a year later, the grower cut back the top of the stock but not the roots. In this case there were too many roots supplying too little foliage. The balance between the amount of foliage and the amount of roots was upset. The roots could not absorb all the water and the 3,000 grafts died from root rot. Container size and its relation to the plant's root and foliage mass is critical to the good health of the tree and the application of thoughtful watering practises, which I think means watering when the individual tree needs it by checking the soil. Choosing the wrong container size can add another variable that works against growing a healthy bonsai. Three-Footed Pots When using a three-footed container, a single foot is placed to the front except in the case of a cascade tree where two of the feet should face the front. This is necessary because the weight of a cascade tree that leans forward and to the side can tip over more easily without the support of a foot directly underneath it. Drilling a Manufactured Container When Mr. Nakamura's son, Makoto Nakamura, drilled 5/16 inch holes in a manufactured dish-shaped pot, he first placed the container upside down over a dirt pile to help support the pot. Pot Shape According to Mr. Nakamura, an oval container can be used for both trees with straight trunks and trees with curves.