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1) Heavy enough to gently anchor the rootball of the plant into the pot, also includes forms of muck used to secure plants on root-over-rock styles or on flat rock bases; 2) Solid enough to prevent drying out of roots from exposure to air or light and prevent surface insects from feeding on the roots, also includes forms of muck used to secure plants on root-over-rock styles or on flat rock bases; 3) Light enough to allow gases to move through the soil to and from the roots without having air pockets, and to allow excess water to freely drain from between the particles; 4) Irregular surfaces of the soil particles to act as reservoirs for small amounts of moisture and nutrients for the roots; 5) Texture and color is complementary to the bark, foliage, exposed larger roots, and pot itself without distracting from them. Akadama (the most prized component, a naturally occurring, granular clay-like mineral, the best quality of which comes from volcanic soils in certain parts of Japan, but it does breakdown after a few years' use, and its high price and fluctuating availability are reasons to use other products; also known as red loam); Decomposed granite (natural processes have weathered this to become a mixture of sand and small granite pebbles; often sifted by bonsai enthusiasts to remove fines); Builders sand (large-grained; can also use large-grained "ant sand" from ant mounds once the fine particles have been sifted out, this sand has been soaked, seeds in it have sprouted and the seedlings picked out); Pea pebbles (smooth pebbles); Pea gravel aka chicken or poultry grit (smaller, somewhat smooth, crushed-rock pebbles, often used for roofing purposes); Natural-colored aquarium gravel; Lava rock (a pulverized volcanic rock with a porous texture and mineral-rich composition); Vermiculite (a 2:1 clay hydrous phyllosilicate mineral which undergoes significant expansion when heated before being put on sale); Pumice (a pulverized super-heated, highly pressurized rock that was rapidly ejected from a volcano); Perlite (a pulverized light-weight amorphous volcanic glass that has a relatively high water content); Styrofoam (a closed-cell extruded polystyrene foam, can be gotten from larger formed pieces that are torn apart); Turface (a unique blend of 50-70% calcined clay, 10-30% sand, 5-15% silt, and 5-10% organic matter that helps to improve soil structure, increase water infiltration, and reduce soil compaction; it is known to break down after a few years' use); Unscented nonclumping plain cat box litter; Leaf mould or pine needles; Shredded or composted bark; Potting soil or compost (commercial blend sifted to remove fines); Bonsai soil mix (commercial blend); Cactus/succulent or orchid mix (commercial blends); Coconut coir fiber; Peat moss (sphagnum moss that dies, decays, and settles at the bottom of a peat bog; the major ingredient in muck); Loam soil (typically consists of about 40% sand, 40% silt -- a granular material of a size between sand and clay -- and 20% clay); Sifted top soil; Horticultural charcoal (a mid-range heated charcoal that enriches soil and absorbs bad odors, usually made from coconut husks or hardwoods); Extra soil from this specimen's collecting/wild dig; Osmocote (a slow-release fertilizer within tiny, light-colored polymer-based granules or spheres or some other fertilizer bits). Heavier soils will be higher in organic material that holds water, of use in dryer climates where multiple waterings each day would be impractical. For more succulent specimens, a lighter soil which is very sandy and rocky is needed which does not hold much moisture. Conifers are said to do better in mostly inorganic soil mixes. Bald cypresses are one of the very few plants which can live in very moist soil conditions. Virtually every pot must have at least one drainage hole, at least 1 cm in diameter. Quantity and size is based on the size of the bottom of the container. Cover each of the larger holes inside the pot with a piece of pottery crock, a small flat stone, ceramic piece made for such a purpose, or metal/plastic wire/screen. Larger pieces of screen can be held in place with a piece of wire that starts and ends on the bottom of the pot on either side of the drainage hole and which passes through the screen inside the pot. Sift out from the soil mix fine particles, sticks, leaves, larger rocks. Larger pots may have additional small holes for running wire through to secure the rootball in place. Put a small layer of the soil mix in the bottom of the pot, then add and position the root ball, and more soil mix, working the soil particles between the roots with your fingers or chopsticks. Shake the pot gently. In a noncadence pattern, gently tap the pot on the ground or workbench surface or with the palms of your hand to help settle the soil mix around the roots. Except for the special case of succulents, with a sprayer or watering can rosette gently give a thorough first watering to completely moisten/break the surface tension of the soil particles and wash finer ones out the bottom. Water a few times so that water drips freely out of the bottom drainage holes. This is usually done during the dormant period, in later autumn/fall or in late winter/early spring. It is NOT done in the middle of Summer UNLESS it is an emergency situation, such as the tree is knocked out of its pot, the pot is damaged and there is no similar sized container available, or if it is determined that the soil remains too wet or compacted as is. With fingers or a tool, rake out the soil from the roots along the edges of the rootball. Roots that have started to knot or wind around the inside of the botton are usually cut off, as well as roots that hang down excessively when the plant is held up. Any visibly dead or rotted roots would also be removed at this time. The tree is repositioned, either in the same style or rotated for a preferred new style, in the chosen pot wiring up from bottom drainage hole or held down with a surface rock if necessary. If there is visible whitish Mycorrhiza in the old soil (which should NOT after a putrid or rotting odor), innoculate the new soil with some of it. Fresh soil mix is added and tapped or chopsticked in, and then gently but thoroughly watered. Decorative moss can be applied if desired and a second watering given. Following repotting, the tree is usually kept in partial shade for at least a few days to allow new root growth to occur before too much moisture is lost due to foliage transpiration. Some enthusiasts for frugal or availability reasons choose to re-use soil removed during repotting. Depending on the components making that soil up, it is highly recommended to solar-sterilize old soil by putting it in a closed black plastic bag and letting it sit in the sun for possibly two weeks, especially in the summer. This is to kill/destroy harmful insects, disease-producing organisms, and noxious weeds including undesirable types of invasive moss in the old soil so that they will not infect a new plant. Similarly, it is recommended to thoroughly clean a pot before reusing it, even with a bleach solution and then rinsing several times with plain water. Obviously, before re-using old soil you want to remove any particles, leaves, sticks, etc. in the soil that appears to be diseased, slimy or moldy. Old soil that is not obviously diseased can also be incorporated otherwise in a garden or landscaping. "The soil of these [Fa-Tee or flower gardens near the port of Canton, China], and indeed of the banks of the [Pearl] river, to a considerable distance, consists of a strong alluvial clay. The plants are either kept in the ground, or they are placed in pots, which are invariably filledwith the same clay as the soil. The clay, at lesst on the surface, both of the ground, and of the pots, is broken into small cubical pieces of about half an inch in size. This soil has, no doubt, many advantages in the climate of Canton, where violent rains, and droughts of long continuance, are very common: for the small lumps of clay do not readily coalesce and run together, in consequence of the rains, or necessary waterings; but it is very obvious that plants so prepared, cannot be generally well suited for the purpose of transportation." "Observations on the Difficulties which have existed in the Transportation of Plants from China to England, and Suggestions for obviating them" by John Livingstone in 1819 for the Transactions of the Horticultural Society of London and published in 1820 "...[an air-layered branch once showing roots] should be detached from the parent tree, and planted with the moss still round it in a small pot in very poor soil ; as soon as it begins to grow, it should be shifted into another pot a little larger ; and this shifting should be repeated several times, into larger and larger pots, always using poor stony, or gravelly soil, and giving the plant very little water... "Dwarfing" in The Ladies' Companion to the Flower Garden, Being An Alphabetical Arrangement of All the Ornamental Plants Usually Grown in Gardens and Shrubberies, with Full Directions For Their Culture (1841, 1865 Eighth Edition) "Then, by the use of very shallow pots, the growth of the tap roots is out of the question; by the use of poor soil, and little of it, and little water, strong growth is prevented." "How the Chinese Make Dwarf Trees" from Scientific American (1862) "It is, however, wonderful to see miniature oaks, chestnuts, pines, and cedars, growing in flower-pots, fifty years old and yet not a foot high. To do this, take a young plant, cut off its tap root, and place it in a basin in which there is good soil kept well watered [sic]. "Dwarf Trees of China" in Health (1884) "These dwarfs are the result, in part, of mechanical processes which prevent the spreading of branches, and in part, of a starving process which consists in cutting most roots, and in keeping the plant in poor soil." Experimental Evolution: lectures by Henry Varigny, D.Sc. delivered in the "Summer School of Art and Science" University Hall, Edinburgh (August, 1891) (London: Macmillan and Company, 1892) "Repotting. -- This is done by us once in two or three years, as follows : -- Lift the plant out of the jardinière, and with a sharply-pointed stick remove about one-third of the old soil around the edges and bottom, cutting away a portion of the old, fine roots, but none of the strong roots, then replace the plant in the same jardinière, first looking to the drainage. For a small shallow jardinière, use a flat piece of tin or a flat crock over each hole, and over this spread some rich, fresh soil ; neatly balance the plant, and fill up with the same rich fresh soil to within 1/2 in. of the rims, and make it sufficiently firm around the edges of the jardinière to prevent the escape of water, it being of the first importance that the entire ball of soil be moitstened at each application. Should the plant be neglected and the soil become quite dry, put the jardinière in a tub of water for ten or fifteen minutes, and if the dryness is not very great the plant will recover. In the case of large plants, concave crocks should be employed for drainage, such are as used by growers of specimen plants..." "How the Japanese Grow the Dwarfed Trees in Jardinières" from Gardeners' Chronicle (1899) "Let the plants be potted in turfy loam, to which an eighth part of leafmould has been added, potting firmly, and mingling the soil intimately with the roots from bottom to top, and putting it in by handfuls only, making it firm as the work proceeds..." "Dwarf Japanese Trees, Climbers, and Shrubs" in the section "Answers to Correspondents" to E. Perkins in The Gardener's Chronicle (1903) "Repotting is performed every second or third year, about a third of the old soil being worked away with a sharp-pointed stick and fresh being added, the plant not being transferred to a larger pot unless it is absolutely necessary." "Queer Fashions in Gardening" by H.C. Davidson in The Country-Side, A Journal of the Country, Garden, Nature, and Wild Life, ed. by E. Kay Robinson (1906) "The soil in the pot should be so heaped that the part where the plant peeps above the surface is the top of a small mound. The root of the plant appears a little above the top. The foot of the mound is a little lower than the brim of the pot. "To cover the surface of the soil with deep green moss largely contributes to the elegance of the potted tree. There are mosses and mosses: for example, the mildew-looking moss which grows on a forest tree among mountains, the beard-like silvery moss which is found on the shady side of a trunk, and what not. Whatever kind of moss you may select, the first thing you should keep in mind is to reproduce Nature in the pot." "Bonsai: Culture of Dwarfed Trees in Japan" by Kiyosh Sakamoto in Gardeners' Chronicle of America (1922) "Since a great deal of water is applied, it is essential that the soil be well drained. Fine copper wire netting is placed over the hole in the bottom of the pot, for perfect drainage; this is covered by a layer of soil with particles the size of grains of rice; finally the pot is filled with soil having finer particles (the size of grains of millet). Both of these soils consist of a mixture of equal parts of red clay subsoil and fertilized topsoil. These well sieved granulated soils allow good drainage and never hold excessive water. Even when water is given every thirty minutes, it runs through the hole immediately, and so the soil is kept sweet and well aerated. The soil may be sterilized before use, to destroy insects and disease-producing organisms. When I bring soil home, I sieve it into three or four grades according to sizes of particles and expose it to the sun for several days until it is smooth and dry as sand." "Miniature Bonsai" by Zeko Nakamura in Handbook on Dwarfed Potted Trees, ed. by Kan Yashiroda (1959), pg. 43 "For potting soil for zelkova bonsai I use loamy soil from cultivated land or sandy loam from the mountains. The soil is sifted through a sieve (1/8-inch mesh), and used only after it has been well and thoroughly dried. The tree should be planted in the dry soil in the pan, and the pan shaken several times after planting. The surface of the soil is then leveled and immediately watered gently and thoroughly with a watering can. The soil should never be pressed." "Japanese Zelkova Bonsai From Seedlings" by Sinkichi Kano in Handbook on Dwarfed Potted Trees, ed. by Kan Yashiroda (1959), pg. 62 "If the plants are in unhealthy condition because of overfertilizing, decaying roots, etc. reduce the amount of leaf mold when preparing the soil for repotting. Before being used, the mixed soil should be sorted into two or three grades differing in size of particles, by sifting through sieves having meshes of various sizes. If it is divided into two grades, the coarser-grained should be placed in the container first, filling it two thirds from the bottom, with the remaining third filled with the finer-grained soil. If three grades are used, the coarsest should be used for the bottom of the container, the medium grade for the middle third, and the remainer filled with the finest grained soil. Finely pulverized soil should never be used; the smallest soil particles should be removing by sifting, and thrown away before the soil is mixed." "Satsuki Azaleas as Dwarfed Potted Shrubs" by Tomisaku Ugajin in Handbook on Dwarfed Potted Trees, ed. by Kan Yashiroda (1959), pg. 62 "The first step is the preparation of the soil mixture, which mixture will vary according to the tree used. One possible mixture is red clay and half-fertilized top soil or top soil and leaf mold -- with river sand (or partially decomposed granite) used for drainage where required. Leaf mold should be included for trees accustomed to the excellent soil provided by decaying leaves (which condition is not found in desert soil)." Bonsai: Dwarfed Beauty in Living Trees by Woodward Radcliffe (1961), pg. 8 "The kind of soil used for miniature bonsai is of great importance, yet it is also a highly individual matter. If authorities are consulted, no two authors seem to agree on soils and soil mixtures, nor is it probable that what works for one grower will automatically be the proper mixture fo another. A soil expert advocates that a good soil mixture for bonsai should be made up of mineral and organic particles with no less than 50 percent "pore space" or empty spaces between the particles. These pore spaces are alternately occupied by water and a combination of gases. "It is customary in Japan to sift soils, usually comprised of clay granules, into as many as seven different sizes, then reconstituting the different sizes for varied plants. Some Americans, on the other hand, have been successful with little attention to the soil grading. They simply substitute coarse industrial sand and humus or other materials for the clay aggregates. Humus is the matter which holds the soil particles together in granules and occurs as an advanced step in the decay of organic material. Humus disappears rapidly from frequently cultivated soil which then loses its granular consistency. Therefore, soil collected from the root zone of a long established pasture or hay field is better than that from a cornfield or vegetable garden. When soil is collected it can be sieved into three or four grades according to the size of the particles and then exposed to the sun for several days until it is smooth and dry as sand. It may be sterilized before use, to destroy insects and disease producing organisms. Packaged so-called potting soil is not recommended, being extremely fine and already sifted the granular structure is missing... "For the amateur it is sufficient to know that a fine loam soil provides a good growing medium for miniature bonsai. The beginner should try out various soils; there is no better teacher than experience." Bonsai Miniatures Quick &Easy by Zeko Nakamura (1973), pp. 17, 19 "Because bonsai trees are grown in soil that is prepared by the trainer, the selection of soils is very important. It is essential that bonsai soils be air permeable and provide good drainage. The soils should also be suited to the climate where the bonsai will be raised and should be easy to acquire. "Each soil has distinctive features: Coarse reddish soil retains moisture well and provides nourishment. Smooth, hard, sand-like soil is air permeable and drains well, but tends to dry out faster and is low in nourishment. "The advantages of both types of soil can be enjoyed by using a combination of the two. A greater proportion of sand-like soil is preferred in rainy climates or for use by bonsai growers who are able to water their plants several times a day. Greater quantities of reddish soil in the mixture are preferred by persons having less time for watering or in cases where bonsai are set in airy, open places. Thus, the proportion of soils in the mixture is based on the bonsai's environment and upon the kind of care it will receive." The Essentials of Bonsai by the Editors of Shufunotomo (1982), pg. 59 See also the several pages about soils in Japan in Bonsai, Miniature Potted Trees by Kyuzo Murata (1964), pp. 29-31; Practical Bonsai for Beginners by Kenji Murata (1964), pp. 71-76; and The Masters' Book of Bonsai, compiled by the Directors of the Japan Bonsai Association (1983), pp. 108-109. And for a global perspective of bonsai soils, refer to The Bonsai School by Craig Coussins (2002), pp. 69-73. Consider studying the more recent "Bonsai Soil" by Bonsai Empire, "DIY Bonsai Soil: Recipes & Guide for Creating Your Own Mix" by Hana Sato (2024), and "What Soil for Bonsai? -- The Perfect Mix" by Bryan Joes (2025). We close with three brief Japanese recipes from Kenji Murata's book (above), pg. 76: "1. Coniferae: 50 percent red loam [aka akadama] and 50 percent sand, or 30 percent red loam and 70 percent sand, or 100 percent red loam. "2. Other trees: 60 percent red loam, 30 percent sand and 10 percent leaf mold, or 70 percent red loam and 30 percent sand and artificial fertilizer. "3. Flower and fruit plants: 50 percent red loam, 30 percent sand and 30 percent leaf mold." |
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