Junipers by Rudi Adam

by Rudi Adam

Juniper may occur with either juvenile (needle like) or socalled adult (scale like) foliage. Species that are strongly variegated or carry both types of foliage at the same time are considered unsuitable for bonsai cultivation.

Junipers are a firm favourite with serious bonsai growers and demonstrators. Their flexibility, growth habit, evergreen fine foliage, bark structure and relatively long life span, makes them ideal bonsai subjects. In older specimens they are more often than not portrayed with dead sections of wood, which increase the apparent age. They are also relatively easy to maintain after the initial training period, but they do not develop any noticeable increase in girth of the trunks once in a container. Junipers do not like dry air and indoor conditions for too long and may suffer badly from "red spider mite" due to dry conditions. In recent years we have also experienced a sort of fungal problem, especially with "Sergeant junipers'. The application of a copper based fungicide such as 'Virikop' can solve the problem.

Wiring and shaping into curves and twists is an integral part of their training. After establishing a shape that is suitable just plucking of excessive foliage wiIl keep the tree neat and tidy. Most junipers like a weIl drained and slightly alkaline soil mixxture (alpine conditions with lime rock and acid compost to break it down) or some charcoal in the soil mix, also more misting than watering is recommended since they do not like wet feet.

The most frequently used Juniper species are:

  • Juniperus procumbens (juvenile foliage-spreading habit)
  • Juniperus procumbens nana (juvenile foliage - spreading habit)
  • Juniperus virginiana (juvenile foliage - upright habit)
  • Juniperus sargentii (adult foliage - semi upright to . . spreading habit, top of the range)
  • Juniper X media Blaauw (adult foliage - semi upright)
  • Juniperus communis (juvenile foliage - upright habit)
  • Juniperus pfitzeriana aurea (adult foliage - bushy habit with a more yellow tinge)

There are also a larger number of so called garden varieties, such as Grey Owl, Gold Coast etc., that are used but they may not be as durable as original species, the one advantage is that they grow a lot faster.

It is a fact that most "chinensis" species are lime lovers, adding some charcoal to the soil mix will improve the growing conditions.

It is important that the majority of junipers can and should receive similar treatment.


Juniper roots are in essence of an adventitious nature, this means there are a lot of fine roots and larger more substantial roots are scarce. Due to the possible infection of a root fungus called "Phytophtora" a leaner (sandier) soil mix is in order. Because it is adventitious the root system may also be kept relatively small and is therefore useful for Literati, Mame and Root on Rock plantings.

An important point to remember is that after drastic branch foliage pruning, either half pot, (remove 50% of the bottom section of roots) or only mist overhead for a period of 10 - 14 days, otherwise the tree may shut down its total root system causing the demise of the tree. Many Junipers have died due to ignorance of this fact.


The bark is normally a reddish brown, smooth when young and more fissured as the tree matures, slightly flaking with the bark peeling in strips. The wood is porous but easily treated with lime sulphur which makes it more durable. Dry brushing or brushing with soapy water twice a year will benefit the tree. As mentioned earlier trunk expansion is relatively slow.


It is almost impossible to train branches into the right direction without wiring. Even new growth may be gently guided into the right direction. Once the branches are set, plucking the new foliage will be enough to maintain its shape and form.


I call it foliage rather than leaves as they do not resemble the latter but are of a scale or needle like nature. This foliage may last for two or three years, but will eventually go yellow, then brown and then drop off. Evergreen means that there is always green foliage, not that foliage never falls off.

Avoid blotchy variegated varieties where one branch or branchlet may turn white or blonde, thereby creating a visual hole or apparent empty space in your design. Evenly variegated varieties, on the other hand are quite alright, but try to limit their numbers in one's collection, too many of them may be boring to the viewer.

Frequent finger nipping of the foliage will retain and increase its density and therefore a more lush appearance.


Keep in a well ventilated but protected (from fierce afternoon sun) area. Water frequently overhead to minimize insect infestation (mites) and retain the normally lush green coloration. A frequent fertilizing proogram with a high nitrogenous content and use a preventative insecticide against Phytoptora is essential to in the care of Junipers

Re-potting for smaller specimens should be done every two years, medium to larger trees should be re-potted every three to four years in late Spring (September - early November)

Soil medium should be slightly sandy with an alkaline influence (Lime). The addition of some charcoal in the soil medium, especially chinensis variety is highly recommended. For emergencies, lime sulphur may be diluted (50 - 1) with water and applied as a soil drench.

Wiring is best done from Spring to Summer and again in late Autumn to early Spring.

Foliage nipping for maintenance should be done whenever new growth exceeds 20mm.

Foliage that turns grey or silver in their coloration is more than likely an attack of either mites or a fungus.


By using the different species all styles are possible.


Spraying overhead with water especially during the dry hot period reduces the chances of red spider mite infestation. Scale (both leaf and branch varieties) may still pose a problem from time to time. Woolly aphid may occur on trees that are weak and root systems may suffer because of the dreaded Phytophtora, root fungus. Treat this fungus with Ridomil MZ, Fungarid or an equivalent. For a preventative measure and to wet the soil properly use 1tsp of Gypsum per litre of soil, 3-4 times per year, either as a dry application on the surface - to be watered in or as an already diluted solution.

Virikop as a fungicidal spray from time to time may be advantageous to the tree.


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Random Bonsai Tip

If your trunk lacks taper split the base of the trunk from below and plug the ends open with a piece of wood or a small stone.