(Original article by Charlie Mosse, modified for the Northern Nevada Environment and local businesses by Rain Shadow Bonsai Club)

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INTRODUCTION

Selecting the right plant for bonsai requires both practice and a bit of research. Jonas Dupuich of Bonsai Tonight (bonsaitonight.com) offers a valuable five-part blog series called “Identifying Suitable Material for Bonsai.” Each post provides guidance on what features to look for when choosing a tree. Reading through all five entries and taking notes is highly recommended, especially for beginners, as it simplifies the selection process.

LEARNING ABOUT JUNIPERS

For those interested in growing junipers, a helpful video presentation is available from Jason Chan of
Eastern Leaf Bonsai, sponsored by the Golden State Bonsai Federation (GSBF). Jason demonstrates
techniques using a Dwarf Japanese Garden Juniper, which is also featured in Jonas Dupuich’s blog posts.
To find the video, search for “Jason Chan GSBF juniper” on YouTube.

REPOTTING SEASON AND SOIL PRE-MIXES

Repotting season is approaching, with peak activity occurring in March, April, and possibly extending
into May. September can also be suitable for repotting, provided temperatures are not excessively hot.
For those who prefer ready-made soil, reputable sources include Bonsai Tonight, Eastern Leaf, Bonsai
Unlimited, Stone Lantern, Bonsai Outlet, and Greenhouse Garden Center. Most of these retailers also
offer individual soil components for those who wish to create their own mixes.

ESSENTIAL SOIL COMPONENTS AND WHERE TO FIND THEM

There are several important components to consider when making your own bonsai soil mix:

• Scoria: This can be challenging to find in bulk or in economical bag sizes. Bulk quantities are
  available on Amazon. Local landscape suppliers, such as Genoa Tree and Greenhouse Garden
  Center, may also have it.
• Pumice: Pumice is easier to source in bags, but bulk availability remains limited. The UniGrow
  brand offers the preferred particle size and generates less waste, such as dust and fines.
  Greenhouse Garden Center stocks EB Stone (8 quart) and SOL Soils (2 quart); it is best to call
  ahead to confirm availability. Dry Stall, a horticultural pumice used in horse stalls, can be found
  at feed stores, Home Depot, and Tractor Supply, though it contains more dust and fines than
  UniGrow. Carefully inspect Dry Stall bags before purchasing. Washing pumice or scoria before
  mixing is useful, but not necessary. After repotting, water plants thoroughly to settle the soil
  and rinse out dust and fines.
• Japanese Kiryu and Hyuga: These high-quality forms of pumice are mostly available online.
  Though more costly, some prefer them for their superior quality and natural, earth-toned color
  compared to pumice mined in the United States.
• Bark: Fine bark, about a quarter inch in size, is still available and suits larger trees. It is generally
  not useful for trees under twelve inches tall. Fine Grade bark, which can be screened for smaller
  pieces, is better for smaller trees and shohin. UniGrow and Orchiata offer suitable grades for
  bonsai use.
• Akadama: Available from the previously mentioned retailers and on Amazon in 2.5-pound or 5-
  pound bags.
• Granite: Granite is helpful in mixes that require faster drainage and adds trace minerals. It can
  sometimes be obtained by screening decomposed granite from landscape yards or river sand.
  Collecting granite from the Sierra Nevada mountains is possible. Use limited amounts, especially
  in medium or large containers, as granite adds significant weight. It is most effective in smaller
  pots, particularly for pines and, to a lesser degree, junipers.
  
  RECOMMENDED SOIL MIXES
  For advanced members, Ken’s RSB Club soil recipe consists of one-part sifted compost, one-part sifted garden soil, one-part decomposed granite (DG) sized 3/8″ to 3/32″, and two-parts sifted pumice. A window screen can be used as a sifter. Akadama is also a suitable soil ingredient, though it contributes little organic matter. Another widely used mix is the Boon mix, made of equal parts pumice, scoria, and akadama.
  
  You can adjust any soil mix by varying its components to retain more or less water. Increasing the percentage of pumice and reducing granite grit or organic material will result in less water retention.
  
  Adjusting particle size also affects water retention; larger particles hold less water, but, with proper watering, they can enhance root growth. In Northern Nevada’s low humidity, it is necessary to include higher levels of organic material in your mix.

ADDITIONAL TIPS AND COMPONENTS

In windy or warm areas, a top dressing of coarse sphagnum moss can be beneficial. Quality sphagnum is available online and at reputable nurseries; look for long-strand varieties.
Drainage screens are essential and can be purchased online or locally at Hobby Lobby, where they are
sold as 7 Mesh Colored Plastic Canvas Sheets (10.5 by 13.5 inches).

COMMERCIAL BONSAI SOIL MIXES

Many companies offer their own bonsai soil mixes, but most are not ideal for bonsai containers, though
they are suitable for young plants. EB Stone’s bonsai soil, now in its third version, is available at
Greenhouse Garden Center. It contains scoria, pumice, and good-quality organic material, making it a
solid choice for the local area.
Sifting soil through a small-mesh screen will result in losing about half the mix due to excessive fines.
Using a window-screen-sized sifter reduces loss to about a quarter of the mix. The fines left over from
sifting can be repurposed. After sifting, add the desired proportions of pumice, scoria, and bark to create
a suitable bonsai soil mix.