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10 things to do to prep your Bonsai for the growing season - Growing Mediums and SAkadama

Updated: Aug 16, 2021

The new growing season is upon us and time is running out to get everything we need. It can be a bewildering time with so much to decide but with this series we will look at all the necessary items we will need over this 10 part series.

Growing mediums and Substrates

For any Bonsai tree it all starts at ground level, the growing mix or "soil". If you get this part wrong then your tree will suffer from under or over watering and even nutrient deficiencies.

We use the term growing mediums as this better defines what we use in Bonsai. Growing mediums is the material wherein trees develop their root systems. It is possible to be a single material only or a mixture of many different ones. The growing medium is chosen to give adequate aeration, water requirements and correct growth at the stage of development of your Bonsai.

Soil on the other hand is a mixture of organic compounds, like: minerals, gases, liquids and organisms that combined support life. The main difference between soils and growing mediums is that soils occur naturally and are known as top soil as well, where growing mediums are correctly managed media created to fill the needs of a plant, usually in a container. Using soil in a container or bonsai pot does not work due to its small surface area and compacts creating drainage and nutrient deficiency problems.

Characteristics of Growing mediums are:

  1. Drainage

  2. Aeration

  3. Water holding capacity

  4. Weight or density/texture

  5. Cation Exchange capacity (CEC)

  6. pH

  7. Soluble salts

SAkadama - South African Akadama

SAkadama characteristics:

  • High quality SAkadama available in 1.0mm - 8mm (Fired to 600degrees)

  • Can be easily sieved into 3 different grades

  • Higher water retention than standard Akadama (65% versus 45%)

  • Neutral pH

  • Retain nutrients for roots

  • Maintains CEC (Cation Exchange Capacity)

  • Remains structurally stable over a long time

  • Fired at high temperature to avoid breakdown of substrate and compaction

  • Free draining mix, less than 5 second draining time

  • Free of weeds and pathogens

  • Holds onto sufficient moisture to help in development

  • Creates a balance between water and aqueous vapor in the medium

  • Enhances and extends fertiliser efficiency.

SAkadama is a South African product manufactured to exacting specifications. It is mined, crushed, screened and then heat treated to 600 degrees Celsius. It’s excellent absorption properties are enhanced by heating it to elevated temperatures. This in turn ensures the particles are hard allowing the product to be used for many years as it does not easily break down. Its excellent water holding capacity of 65% , high cation exchange capability and 30% air filled porosity ensures the plant is continually fed with nutrients. This allows for less frequent watering and ensures strong and healthy plant growth.

Why use SAkadama?

SAkadama has been in development for over a year now. Through extensive lab tests, real world tests and loads of data being compiled, we have seriously done our homework...

Returning from overseas we very quickly realized that in South Africa we needed a cost effective growing medium on par or better than what was being used in Japan, Europe and America. Being in Europe and repotting trees at Bonsai Sense with Rafael Torres we got to experience how Akadama and Pumice worked, plus using other substrates for various different species or development phases. This got the ball rolling that on return to SA we immediately got into development for a local product.

Why not just import? Well firstly price is a huge concern for SA. Not everyone can afford to plant their trees into high quality mixes and most mix their own growing mixes because of this. The first priority was to make the product affordable to open it up to more Bonsai growers and other hobbyists.

Secondly we needed a product that from the onset had SA conditions in mind. Due to our varying conditions from coast to inland we needed something that would drain well yet have sufficient moisture retention for our African heat. Lab tests comparing SAkadama to Akadama yielded a 20% increased moisture and nutrient absorption rate while still keeping drainage and aeration at optimal range.

SAkadama has the same composition as Akadama from Japan. The only difference is 5% less iron. We heat treat to much higher temperatures(600degrees) than Akadama to create a stronger product that is structurally stable for much longer. SAkadama still breaks up for roots to penetrate to gain vital nutrients and moisture that are absorbed in the large surface area of the particle. This in part helps provide an ideal CEC for longer periods of time.

How to use SAkadama?

SAkadama is made to use in conjunction with other substrates. For example Perlite, Leca, Pumice, Pine Bark, Zeolite and other suitable media. We have been hard at work creating ideal ratios for different conditions and species that are available in our Premix Bags. We have 3 Premixes available as follows:

  1. Premium Mix - Our top of the range mix with ideal ratios of Perlite, SAkadama and Pine bark. This mix is ideal for the majority of tree species in varying conditions. It comprises of 40% SAkadama, 40% Perlite and 20% Pine Bark. The organic contest is very important for some nutrients and moisture retention. Only 20% is needed to help the tree flourish and develop amazing fine root structures. Always use in conjunction with Chilean Moss as a groundcover to lock in moisture the first 2 months after repotting. Recommended Species: For use on all deciduous trees, eg. Celtis, Acer, Ulmus or Elm, Cotoneaster, Pyracantha, Syzygium, Duranta, Juniperus, Pinus, Picea, Myrtus, Dovyalis, Buxus, Taxus

  2. AkaPerl Mix - This completely inorganic mix of 50% SAkadama and 50% Perlite is the ideal mix for any drought hardy or succulent type plant. Species that will do amazingly well are Portulacaria, Commiphora, Baobab, Adeniums, Bougainvillea and any succulent. The combination of SAkadama and Perlite hold onto nutrients and enough moisture to keep the plant healthy. Always use in conjunction with Chilean Moss as a groundcover to lock in moisture the first 2 months after repotting. Recommended Species: Commiphora, Baobab, Portulacaria, Acacia, Olea or Wild Olive, Bougainvillea

  3. Retail Mix - This mix has the most organic content of any mix in the range at 33% Pine Bark, 33% Perlite and 33% SAkadama. This mix is ideal for beginners, plants with high water demands and/or any tree that needs to transition from bad compacted soil to eventually being potted into the Premium mix or AkaPerl. The increased water holding capability creates a buffer between watering to help the grower develop his skills as a beginner. A tree that is not healthy or has been damaged by incorrect growing media will be able recover from certain factors like overwatering or nutrient deficiencies. Always use in conjunction with Chilean Moss as a groundcover to lock in moisture the first 2 months after repotting. Recommended species: Swamp Cypress, Salix or Willow, Ficus, Wisteria, Dovyalis or any species coming from low quality mix or soil.

In Part 2 of this Blog series....

We will discuss repotting procedures and how to get the most out of your growing mediums plus Bonsai pot prep, wiring in a bonsai and why using bioroot as an integral part of repotting and aftercare.

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