Black Pines - Bonsai Lesson Plan

Informal Upright Style Bonsai
Scientific Name: Pinus thunbergii

Many consider that Japanese black pine is the ultimate in the art of bonsai. There are very few trees that convey the classic power or majesty to the degree that a black pine can portray. This tree takes many years to achieve the maturity and majesty of classic bonsai. So when undertaking a black pine as a bonsai it is important to commit yourself to ensure that you can do the best you possibly can to ensure the future of your bonsai. The rewards for this effort are most gratifying and you will possibly hand it down from generation to generation. This in itself is a responsibility, but the end result will be a very old bonsai. Saburo Kato a Japanese bonsai master maintains and cares for a 400 year old bonsai. (How rewarding is that?)

Working with black pines is a fine balancing act; the main requirement is a constant ongoing maintenance in all areas. This includes shaping, trimming and cropping of the foliage. If constant attention is not maintained, the tree will develop long and leggy branches and very erratic foliage. Pines like most trees send all their energy to the apex of the tree therefore weakening the lower branches. Bonsai methods are used to reverse this process.

Placement and exposure: Black pines need full sun all day long providing the temperature does not exceed 100 degrees Fahrenheit otherwise the needles will tend to turn more towards yellow rather than a rich dark green. One method of preventing this is to use shade cloth ranging from 50-75%.

Extreme conditions also affect the root system as there is not a great depth of soil to keep the roots cool. One way of solving this problem is to cover the pot to prevent it from getting to hot.

Morton Bay Fig

Soil recipes used in repotting:

Japanese black pines like a well-drained soil. In Japan these days they are planting black pines in nothing but crushed rock and supplement with liquid fertilizers. A good mixture for Australian conditions is 1 part Akadama to 1 part fine sharp gravel to 1 part Debco bonsai mix which is available from most nurseries, personally I find this to be excellent and is what I use for all my black pines and conifers. With black pines a free draining soil is essential for the reasons in preventing root rot because the soil has become waterlogged.


It�s important to keep black pines evenly moist but not to damp, preferably on the dry side as they are quite hardy and prefer these conditions. A good free draining soil will assist this. When watering, saturate the soil 2 to 3 times to saturate the tray or pot, because you have a free draining soil, this will allow the roots to obtain oxygen.


Pines prefer organic fertilizers, Nitrosol, or Bio Gold are good choices, personally I use a combination of Organic and mineral supplement such as Maxicrop with Nitrosol combined in a liquid form. Fertilizing should begin in September or bud swell which is spring. Also you can supplement later with a good dose of vitamin B.


The most problem pests for black pine are red spider mite, mealy bugs and aphids. A way of detecting spider mite is that the needles will have small black specks on them. Place a piece of paper underneath and tap the branches. If the specks move this is spider mite. The best way to treat this is to use mitacide or lime sulphur, 1:30. Spray on the foliage as well as the branches and trunk and leave for half-an-hour in the late afternoon in a cool spot and then hose off. If this does not work, increase the dosage and repeat the process. For mealy bug spray a strong solution of detergent and water and wipe off with a cotton bud, failing this use confidor or lime sulphur. This can take up to 2, 3 or 4 treatments depending on how heavy the infestation is. These pests usually only will attack weak or stressed trees but can also come into your collection by means of another infected tree that you might have only just acquired.


It is preferable to prune the branches in late autumn or winter; this reduces the sap bleeding from the wound. Seal the wound with honey as this nourishes the cut and protects it from infection. For the removal of major branches this should be done in spring as a major wound will heal faster.

Pines do not take kindly to drastic pruning as this is stressful to them it should only be performed on very strong trees. Reduction should be carried out slowly over a period of years. After pruning is completed the trees should be placed in partial shade or only where they receive morning sun for a period of 2 to 6 weeks.

Root pruning is best carried out in early July, August; young trees every 2 years; older trees every 3 years. Trimming the shoots is carried out in the growing season to force ramification. Pruning in the autumn is effective in forcing back budding but should be carried out on strong, well-fed trees.

"Bonsai is the creation of living art and the blending of elements"

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