Article 84 – ‘Plant husbandry 2’

Hi welcome to Taiga Bonzai, we have discussed what happens below ground with the root system and its functionality, in this article we concentrate on what occurs above ground in the foliage and its production of sugars and starches that feed the root system.

Introduction – photosynthesis is a process used by plants to convert light energy into chemical energy through cellular respiration that can later be released to fuel the plant’s activities. Some of this chemical energy including sugars and starches are synthesized from carbon dioxide and water and stored in carbohydrate molecules. In most cases oxygen is also released as a waste product which stores three times more chemical energy than carbohydrates. 

Photosynthesis process

Light energy – although various species of plant perform photosynthesis in different ways, the process always begins when energy from light is absorbed by proteins in a reaction centre, which contain green chlorophyll and other coloured pigments referred to as chromophores. In plants, these proteins are held inside organelles called chloroplasts, that are most abundant in leaf cells, while in bacteria they are embedded in the plasma membrane.

In these light-dependent reactions, some energy is used to strip electrons from suitable substances including, water and oxygen production. The hydrogen freed via the division of water is used in the creation of two further compounds that serve as short-term stores of energy, allowing its transfer to drive other reactions. These compounds are reduced nicotinamide adenine dinucleotide phosphate (NADPH) and adenosine triphosphate (ATP) namely the ‘energy currency’ of cells.

In plants sugars are synthesised by a subsequent sequence of light-independent reactions referred to as the Calvin cycle. It is here that atmospheric carbon dioxide is incorporated into existing organic carbon compounds, such as ribulose bisphosphate. By using the ATP and NADPH produced by the light-dependent reactions, the resulting compounds are then reduced and removed to form further carbohydrates, including glucose.

The light spectrum – in article nos ’03’ ‘Lighting for bonsai’ we discussed our 3 year research program on different forms of lighting that are used in horticulture production. The reason for this was to find a lighting source that could mimic the spectrum. Included were traditional incandescent bulbs – Tungsten (now removed from the market replaced by energy-saving bulbs) CFLs, (Compact fluorescent lamp) Halogen, HID, (High intensity discharge) HPS, (High pressure sodium) and LED, (Light emitting diode) the latter the only one that could come close to mimicking the light spectrum. 

If we look at the light spectrum shown above, we see a band of colour change from ultra 400 nanometers to infra at 800 nanometers. It is argued in some quarters that plants use the whole light spectrum for growth, this maybe the case in some instances, but in reality plants only use ultra to cyan for growth and red to infra for flower and fruit. The area between ultra and infra approximately 525 to 625 nanometers the middle part of the spectrum called white light is not that beneficial to plants, which has shown to be the case in NASA’s experiments for growing plants in space.

Nutrient movement – soil mediums play an important role in how plants receive nutrients, if the structure is compacted it will severely limit the roots ability to move toward nutrients in addition, it also restricts water movement thus preventing root growth. Properly prepared soil mediums allow for root-run, water movement and drainage, for more on this topic see article nos ’09’ ‘Bonsai soils’. As the roots pump water to the foliage the leaves in return send sugars and starches to the roots, this cooperation between root system and foliage ensure growth and vitality.

The xylem showing nutrient (white) and water (blue) movement

Thus far we have discussed the functionality of the root system below ground (article 82) and now what is above ground – the foliage and its purpose – photosynthesis and transportation of sugars and starches and the importance of light. Although these are crucial elements in bonsai and horticulture production, there are other aspects to focus on including heating, ventilation and water.

Plant husbandry – plants including bonsai endemic to particular regions subjected to the elements of the seasons do not require heating. Established plants will adapt their growth cycles as they have for countless eons moreover, ventilation is not a problem as there is always a constant circulation of air. However, plants from temperate zones (often referred to as indoor plants) do require some form of warmth during the cold times in order to survive and this can cause problems.

For decades building designers and heating engineers have tried to conceal heating systems including radiators by positioning them where they are inconspicuous, usually affixed below windows covered by a shelf. People keep plants on these shelves as it is probably the only natural light source available, but this location is detrimental. (a) Because the constant heat evaporates moisture from the soil medium too quickly and (b) constant watering saturates the root system, which can cause problems such as chlorosis affecting the plants health and vitality.

Turning down the thermostat may help in reducing moisture loss but the area is now at a lower temperature, which can have an effect on the plant’s ability to thrive; the average temperature for most temperate indoor plant varieties is 22 to 26° Celsius. If one moves the plant away from the window area then the problems of light loss becomes apparent, which lessens the performance for photosynthesis and healthy growth; is there a solution to this problem? – Yes move the plants away from direct heat.

Returning to the article nos ’03’ ‘Lighting for bonsai’ you can find many references to different lighting fixtures for example, the Hydroponic full Spectrum CFL grow light bulb a 105 Watt 5500K perfect daylight balanced pure white light bulb H105 costing $24.99. Although this may seem a bargain, do not be tempted because the manufacturers claims are incorrect. These cheaper versions of this type of light bulb are not full spectrum, they only emit red light and not the blue light (ultra) needed for growth.

In addition, much depends on the number of plants in your collection, if large or spread out you will probably need more than one bulb because the footprint (the light arc) of one is not wide enough to cover your plant display. Suspending the lights higher to create a larger light arc reduces the power of the lumens, the closer the light source to the plants the more beneficial it becomes. Plus the added fact that you will have to purchase or create some sort of apparatus to suspend the light fixture.

Moreover cheap bulbs may seem an inexpensive solution but many do not have aluminium heat sink plates and get extremely hot, hence fittings to the power source have to be ceramic not plastic for obvious reasons. Therefore, we urge you to research your needs thoroughly before contemplating any purchase, because the cheaper route is not always the best; it may cost more. The image below is one of our LED lighting fixtures purchased in 2016, it is in use from October to May (8 months for 14 hrs per day) and to date (October 2022) there have not been any problems.

Full spectrum LED light setup

Water – it can be agreed that the only water safe for all plant species is rain water due to the fact that it is pure, soft, uncontaminated and sweet to the taste and if collected in containers can be used without repercussions. However, it is not always possible to collect it if one lives in dwellings where rules restrict this practice, the only other option is to use what comes out of the household tap and this is where the problems begin.

Municipal water or domestic water is full of chemicals including Fluoride (F) that was introduced in the 1940’s to assist in reducing tooth decay, Chlorine (CI) a strong disinfectant added to drinking water as a purification technique. Other chemicals found in tap water include, Mercury (Hg) a by product of mining and industrial practises, Arsenic (As), Lead (Pb) and Glyphosate that are major toxins that can do irreparable damage. To find out more on the problems in using domestic water even for human consumption, read the articles nos ’35’ and ’36’ ‘A Teaspoon of Vinegar’ and ‘A Teaspoon of Vinegar’ Part 2.

If domestic water is all that is available it can still be used but it has to be treated, you will need two plastic containers enough to hold 7 litres of water each. Mark one container ‘alkaline’ for deciduous varieties and the other ‘acid’ for coniferous. The ‘alkaline’ container can be filled from the house tap, but must be left to stand for at least 2 days before use. In the ‘acid’ container add a teaspoon of vinegar (the type does not matter) then fill with water from the same tap, this also has to stand for 2 days before use. The vinegar in the water reacts with the alkaline particles creating black streaks these are not harmful, but it is not advisable to consume it.

Black algae in vinegar treated tap water

Your untreated ‘alkaline’ water is for temperate plants varieties only, never coniferous or any other acid loving species including Magnolia, Azaleas and Rhododendron, use the treated ‘acid’ water for these. In addition, you can use the ‘acid’ solution on temperate and other deciduous plants occasionally, if in doubt read the article nos ’27’ ‘The pH factor’ part I or contact us direct, email address is in the about section under our name and logo. Until next time, BW, Nik.

Article 59 – ‘Fertilizer is not food’

Hi, welcome to Taiga Bonzai in this post we discuss the purpose of fertilizer, often misunderstood and misused.

Introduction – the ideology that fertilizer is a source of food is a misnomer, because plants produce their own food in the form of sugars via photosynthesis and moisture from the soil. The minerals in fertilizer provide the ingredients needed for photosynthesis and growth, when minerals are deficient or absent in the soil, fertilizer is added to maintain an adequate supply.

Plants – in their natural settings are able to survive quite well mainly due to their root systems, which have the ability to spread and travel great distances in search of moisture and nutrients. But bonsai are confined to relatively small containers and thus are restricted from this practice therefore, they have to be fertilized. The questions of which fertilizer to use, solid or liquid, what is the dosage rate and how often to use it, one might assume it would be relatively straightforward and this is where mistakes are made, which in many cases cannot be undone; hence a little more thought on the subject is required.

The pH factor – the first step is understanding from where the plant originates and the soil type in which it is grown be it ericaceous (coniferous) or organic (deciduous) and the relevant pH factor. Detailed descriptive articles on these topics can be found on this site, ‘Bonsai Soils’ March 27th 2016, ‘The pH factor (part I)’ April 22nd 2017 and the ‘The pH factor (part II)’ May 6th 2017, these are important steps in the learning curve of knowing, which directive to adopt; especially for those new to bonsai horticulture.

Soils – of course many horticulturists make there own soil compositions depending on the species and their specific needs, some use Akadama (akadamatsuchi, red ball earth) a naturally occurring, granular clay mineral used as soil for both deciduous and coniferous species, Seramis, Turface and Oil-Dri that are fired clays whilst others will use soil from the same location of where the plant originated; if at all possible.

However, there are other factors to consider because soil contains a multitude of living organisms that consume, digest, and cycle nutrients. These include archaea, bacteria, actinomycetes, fungi, (mycorrhiza) algae, protozoa, and a wide range of insects; mites, nematodes, earthworms and ants all of which are important to the vitality of a soil composition. Such organisms are classed as either acidophiles, (that thrive under acidic conditions) Neutrophiles (that exist in a neutral pH environment) and Alkaliphiles (a class of extremophilic microbes capable of survival in alkaline environments).

Another factor is the balance or imbalance of a soil’s chemical structure and the three primary nutrients are nitrogen (N), phosphorus (P) and potassium (K). Secondary nutrients include sulphur, calcium and magnesium, minor nutrients consist of iron, manganese, copper, zinc, boron, molybdenum and chlorine. Soils with high acidity may have toxic amounts of aluminium and manganese.

Nitrogen (N) is essential for growth and a necessary part of chlorophyll helping plants photosynthesise, phosphorus (P) is needed for the development of flowers, fruits, and root systems. Potassium (K) keeps roots healthy, aids in the flowering/fruiting process and assists in aiding plants tolerate stress to some degree through periods of drought therefore, a soil test kit is advisable to check the balance between them. (See article the ‘The pH factor (part II)’ section Soil testing applications).

Having conducted a soil test and determined the balance or imbalance one can select a fertilizer that will give you the correct amount of nutrients required. On any package of fertilizer be it powder, granulated or liquid there are three numbers that correspond to the amounts of nutrients in the product for example. 5-5-5 is referred to as a balanced fertilizer due to (N) (P) and (K) having equal quantities. Other fertilizers may show a different numbering for example, 4-10-6 which indicates that (N) is low (P) is high and (K) is medium. This numbering system is the same for all manufactured fertilizer products regardless of their form.

However, different species require fertilizers suitable to their needs for example, conifers are not considered to be heavy feeders hence one annual application of a complete garden fertilizer such as 10-10-10 or 16-8-8 will suffice, which can be applied in early spring before the plants break dormancy, or in late autumn. Deciduous trees and shrubs require a more well-balanced fertilizer, in which the three main nutrients are closer in proportion, such as 10-10-10, that provides nitrogen for green healthy foliage, phosphorus and potassium for flowering, fruiting and root development.

Applying fertilizer – how often are bonsai trees fertilized due to their confinement? There are a lot of arguments on this topic because all species are individuals each having their own requirements. Some advocate a weekly basis whilst others state fortnightly or monthly is adequate in addition, fertilizer should be given sparingly after watering has taken place. The general consensus that bonsai can or should be fertilized during the entire growing season from early spring to mid-autumn has logic however, older mature trees are often fertilized less frequently. Much depends on the species, time of year, stage of development and health; indoor trees can be fertilized all year round. The problem with over fertilization boosting the (N)-(P)-(K) levels can weaken and stress out a plant often causing its demise.

Left = liquid – right = granulated

Which form of fertilizer to use, powdered, granulated or liquid? – There are many different opinions from all quarters on this subject, some argue that liquid is better because it is instantaneous, but it usually drains out of the bottom of the container although much depends on the quantity given. Some maintain that a top dressing of powdered fertilizer is better as it penetrates into the soil after watering, although the majority of the particles will remain in the pot there will be a loss due to drainage. Others plumb for granules tiny pellets that are mixed in the soil when the container is being prepared, these are slow release and are preferred by many.

Another factor to consider is the cost of fertilizer, many fertilizers if in liquid form normally come in small bottles and if purchasing online the cost of shipment is added increasing the overall price. A 250ml bottle diluted 4 times (1.5 litres) will not last long during a season although much depends how many trees are in the collection and how often they are fertilized. Whereas half a teaspoon of granulated (slow release) added to the soil medium at repotting time will last at least two seasons. If one is unsure of what fertiliser to use the well known horticulturist and TV presenter Alan Titchmarsh gives a good presentation on this subject. (link to his presentation is given below)

As stated fertilizer is ‘not food’ nor is it a ‘one-size-fits-all’ it is a way of replenishing the nutrients within the soil medium which the plant needs for healthy growth and each species will require a specific level of nitrogen (N), phosphorus (P) and potassium (K) to sustain this. Hence it is advisable to do a soil test before purchasing fertilizer, because there has to be an accepted balance between (N), (P) and (K) for each species, this does not mean to say that you need an assortment of fertilizers far from it; one for conifers and one for deciduous will suffice. Until next time, BW, Nik.