盆栽用土の基本 ～配合・選び方・微塵対策まで徹底解説～ — Transcript

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1. 0:07Hello, I’m Morimae, the navigator of WABI CHANNEL.
2. 0:12As spring reaches this time of year and the cherry blossoms begin to bloom,
3. 0:17bonsai enter the height of the repotting season, as if being urged on by the blossoms.
4. 0:23Whenever we feel the air of this season, we are filled each year with a quiet sense of urgency,
5. 0:29thinking that we must begin as soon as possible.
6. 0:34The repotting season begins with deciduous bonsai, then moves on to Japanese white pine, followed by shinpaku, and finally black pine.
7. 0:42Right now, the repotting season for deciduous bonsai is just coming to an end.
8. 0:46Repotting deciduous bonsai is something that must be done once every two to three years.
9. 0:52Today, I would like to talk about one of the most essential materials we rely on in our work.
10. 1:00It is bonsai soil.
11. 1:01More specifically, it refers to the bonsai soil mix—various types of soil blended together for cultivation.
12. 1:05As many natural materials are becoming scarce, the components used in bonsai soil are also rapidly decreasing.
13. 1:16Within these limitations, we must constantly adapt—experimenting, refining,
14. 1:22and searching for the most suitable bonsai soil mix for healthy cultivation.
15. 1:28Today, I will share various insights about bonsai soil and how we work with it.
16. 1:33Thank you for watching, and I hope you find this informative.
17. 1:44We use a bonsai soil mix made by blending several different types of soil.
18. 1:50The soils are carefully sifted to remove fine particles, and then blended according to the species of the tree.
19. 2:00Various types of soil are prepared, and the grain size, type, and mixing ratio are subtly adjusted for each individual tree.
20. 2:11Without this bonsai soil mix, we would not be able to cultivate and shape bonsai.
21. 2:18It is a precious natural resource that must be used with care.
22. 2:23In many ways, it is this soil that determines the quality and future of the bonsai.
23. 2:31When we talk about bonsai soil and bonsai soil mix, there is one important point I would like to share first.
24. 2:39The type of bonsai soil used varies greatly depending on the natural environment and location—
25. 2:49here in the Kanto region, for example, compared to areas such as Kansai,
26. 2:53Kyushu in the south, or Hokkaido and Tohoku in the north.
27. 3:00We are often asked what kind of bonsai soil mix is best, but what truly matters is where the person lives,
28. 3:10and what kind of climate they experience in that region.
29. 3:13This determines how the bonsai will grow in that environment, and therefore what kind of bonsai soil should be used.
30. 3:21Bonsai soil can be divided into several basic categories, and within those categories,
31. 3:25materials with the same properties may be known by different names—simply depending on where they are sourced.
32. 3:33Therefore, I would appreciate your understanding that what we are explaining here on WABI CHANNEL
33. 3:41is primarily based on bonsai soil used in the Kanto region.
34. 3:46With that in mind, I would now like to introduce the various bonsai soils we use here at Hanyu Uchikutei.
35. 3:55At the core of our bonsai soil is akadama.
36. 4:05It is slightly acidic, with a pH typically ranging from 5.5 to 6.5.
37. 4:12This soil originates from the Kanto loam layer,
38. 4:14formed from the accumulation of volcanic ash deposits over a very long period of time.
39. 4:21It has good moisture retention, while also maintaining a stable granular structure that does not easily break down—
40. 4:30making it an essential base material for bonsai soil.
41. 4:35In our field, this type of Ibaraki akadama is known as “nihon-sen” (two-line grade akadama)
42. 4:41and has long been valued as an essential component of bonsai soil mix.
43. 4:46After its production once ceased, the chairman of Nagahama Shoten in Tochigi,
44. 4:52despite his age, undertook research and succeeded in reproducing it.
45. 4:59It would not be an exaggeration to call it a lifeline for bonsai.
46. 5:03By a fortunate connection, I had the opportunity to assist in various ways during its redevelopment.
47. 5:12To commemorate that time, the shinpaku printed on the package is,
48. 5:18somewhat embarrassingly, one that I created myself.
49. 5:24For that reason as well, it holds a special place for me.
50. 5:26With akadama as the foundation, various other materials are added to create bonsai soil mixes.
51. 5:33To complement akadama, materials with higher drainage are added to improve airflow and allow the soil to dry more efficiently.
52. 5:43These are materials that are closer to sand or stone rather than soil.
53. 5:50In the Kanto region, Kiryu sand, sourced from Kiryu City,
54. 5:53is commonly used because of its excellent compatibility with akadama.
55. 5:59However, it is becoming increasingly likely that Kiryu sand will no longer be available in the future.
56. 6:05Due to concerns over environmental damage from excessive extraction, it may eventually become unavailable.
57. 6:16As is happening in many places, we in the Kanto region are turning to alternatives such as fired sand
58. 6:26—keiseki-zuna (pumice-based substrate)—which is also available at home improvement stores.
59. 6:34Keiseki-zuna has a higher lime content, but provides excellent drainage and helps prevent excess moisture from remaining in the soil.
60. 6:42An even better match with akadama is hyuga soil, a type of pumice sourced from the Kyushu region.
61. 6:51Terms such as hyuga soil or keiseki-zuna are used,
62. 6:57but essentially they refer to materials with similar properties, simply named differently depending on their origin.
63. 7:06In collaboration with Nagahama, we developed a foundational bonsai soil mix for conifers.
64. 7:13We refer to it as a “five-component blend,” a specially prepared bonsai soil produced by Nagahama Shoten.
65. 7:21In the past, all soils were individually sifted and mixed by hand.
66. 7:27However, we wanted a reliable standard blend, so after consulting with Nagahama,
67. 7:33we created a base mix using akadama, Kiryu sand, bamboo charcoal, and other components
68. 7:44—some of which remain proprietary—that can be used on its own for planting bonsai.
69. 7:51Although it is slightly more expensive, we use this five-component blend as a base,
70. 7:58adjusting it by adding akadama, Kiryu sand, or keiseki-zuna depending on the individual tree.
71. 8:08Now, let me introduce the bonsai soil mixes we regularly use here in Hanyu.
72. 8:15The container on the left is for deciduous bonsai.
73. 8:19It is a medium-grain bonsai soil mix used for planting various deciduous species such as maple, trident maple, quince, and beech.
74. 8:27The ratio is roughly 3 parts akadama to 1 part Kiryu sand.
75. 8:34Next is the mix for shinpaku.
76. 8:36For shinpaku, we prefer a mix that dries more quickly and has better drainage,
77. 8:44so we replace Kiryu sand with keiseki-zuna and use the same 3:1 ratio.
78. 8:51For conifers in general, the base becomes what we refer to as the “five-component blend.”
79. 9:00Using this as a base, we adjust the mix each time depending on the tree’s size, age, and stage of development.
80. 9:08In all cases, we also use a coarse layer at the bottom of the pot—what we call “goro-tsuchi”—to improve drainage.
81. 9:18This layer is mainly made from akadama, along with leftover larger particles of Kiryu sand or keiseki-zuna, to enhance drainage.
82. 9:27These form the basic foundation, and from there, the particle size is adjusted by sifting according to the size of the tree.
83. 9:37The mixes shown here are versatile enough to be used for medium to large bonsai.
84. 9:45These are the standard mixes we use in our day-to-day repotting work.
85. 9:56Now, let me show you how we take individual bonsai soil components and blend them together to create a proper bonsai soil mix.
86. 10:05First, I will demonstrate the basic ratio for deciduous bonsai, mixing akadama and Kiryu sand at 3:1.
87. 10:22This nihon-sen akadama (Ibaraki akadama) is sold in different grain sizes,
88. 10:27such as medium and small, making it easy for us to work with.
89. 10:31Nowadays, many types of bonsai soil are available in this way,
90. 10:34which is very convenient.
91. 10:42As a basic mix, this ratio forms the foundation for deciduous bonsai soil.
92. 10:47Of course, this ratio will vary depending on
93. 10:50whether the tree is young, a seedling, or more mature.
94. 10:54Older trees require better drainage, while younger trees need more moisture and nutrients,
95. 11:00so we increase the proportion of akadama for them.
96. 11:04Mixing by hand is the most effective way to achieve a proper blend.
97. 11:08(When doing this, be sure to wear gloves.)
98. 11:28At this point, the mix is well blended.
99. 11:31This forms the basic mix for deciduous bonsai,
100. 11:35but there is an important point to keep in mind.
101. 11:38No matter how carefully the soil has been sifted beforehand,
102. 11:44fine particles will inevitably form as the materials rub against each other during handling.
103. 11:51These fine particles must be removed.
104. 11:54You can also assess the quality of akadama through a simple test like the one I will now show.
105. 12:03Unfortunately, this is where the difference becomes clear
106. 12:06between common akadama sold at home improvement stores and nihon-sen akadama.
107. 12:11Even when firmly squeezed by hand, the particles do not break down at all.
108. 12:17This level of hardness is essential.
109. 12:19If the particles crumble easily when squeezed,
110. 12:23they are not suitable for proper bonsai cultivation.
111. 12:27Now, let me show you how even high-quality soil can still produce fine particles.
112. 12:36This is a step you should always take before planting.
113. 12:53Even with pre-prepared bonsai soil, please take a look.
114. 12:58When you sift it,
115. 13:04even lightly, this much fine material will come out.
116. 13:12This fine dust is what can ultimately harm the health of your bonsai.
117. 13:18It reduces drainage and can lead to soil compaction around the roots.
118. 13:23Taking a little extra time to sift the soil before planting will help prevent these issues later on.
119. 13:34Please watch closely.
120. 13:52These are the unwanted fine particles.
121. 13:56They can cause the roots to become clogged.
122. 13:59It may seem like a small step, but please take care to do it properly.
123. 14:05The soils we have discussed so far are bonsai soil mixes
124. 14:09used for planting medium to large trees.
125. 14:13Finally, I would like to introduce what we call top dressing soil.
126. 14:17Around the roots and surface root spread,
127. 14:20using larger particles can make the soil appear rough and leave visible gaps.
128. 14:25To create a more refined and settled surface,
129. 14:28we sift the “five-component blend” to remove fine particles
130. 14:32and use only the finest grade as top dressing soil.
131. 14:35This fine texture helps create a clean and stable finish around the roots.
132. 14:40Of course, it is especially important to remove fine particles at this stage,
133. 14:43and we apply this carefully prepared soil over the surface of the pot.
134. 14:48While moss may also be applied, this soil is often used as the final finishing layer.
135. 15:02Today, I shared with you the essentials of bonsai soil and bonsai soil mix.
136. 15:09Bonsai soil may seem like something ordinary, working quietly behind the scenes,
137. 15:16but maintaining and passing down these materials requires great effort from the specialists who produce them.
138. 15:25As professionals, it is our responsibility to appreciate their work while continuing to seek better bonsai soil for the health of our trees.
139. 15:36As the natural environment changes, the composition of bonsai soil must also continue to evolve.
140. 15:42Even as we choose soils with better drainage due to warming climates,
141. 15:47we must also consider how to protect trees from winter cold—this process of trial and error will continue.
142. 15:54I hope this encourages you to take a fresh look at bonsai soil.
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146. 16:20Thank you very much for watching today.