Japanese Black Pine Care Guide
When work is done on black pine the trees must be very healthy. If they are not the results will be poor. On a healthy tree needles will be sharp at their tips and stiff. The needles should be uniformly dark green and have a shiny surface. In the spring new candle growth on a healthy tree will be at least an inch long. Weak growth is characterized by little or no elongation of the candle, with needles emerging very near to the base of the bud. Black Pines that are perpetually kept weak will sometimes put out small buds in the interior of the branches that do not produce needles for many years.
The Mikawa variety of black pine is the most commonly used for bonsai and landscape trees; note however that other varieties will have more slender needles, like that of a red pine. They are nevertheless sharp at the point and straight.
The feeding of pines can be done with liquid fertilizer only, but it must be done frequently since liquid fertilizer is washed away when the tree is watered. It is best to use some sort of slow-release fertilizer in addition to the liquid fertilizer. Using organic fertilizer cakes, commonly made from Rapeseed meal and available for purchase from bonsai retailers is one of the most common fertilizing techniques. Cakes can also be made from cottonseed meal or alfalfa meal in combination with fish emulsion and some bone meal. The cakes are placed on the surface of the soil around the tree and last generally about one month. Additional cakes are added each month and the oldest ones are removed as space is needed.
Although soil recipes abound, it is best to remember that Black Pines do well with very little or no organic matter in the soil. A mixture of Akadama and Pumice with a small amount of cocoa or rice hulls is good. Mixtures including D.G., expanded shale and lava rock are also appropriate.
About the first week of December begin to pull needles. This is done in an upward movement, the way the needles grow. Leave about 6 or 7 pairs of needles at the top of the tree; 7 to 10 in the middle; and 10 to 15 pairs on the bottom third and on the inner middle portions. The lower and inner branches of pine are naturally weaker and therefore need more needles to keep their strength.
If the needles do not come off easily cut them off just above the sheath that holds the pair. On short branches do not remove the sheath. New buds will form inside it. On long bare branches remove the sheath to encourage budding further back along the branch.
In the first week of January remove two more pairs of needles from each branch on the whole tree.
Wiring can be done after the first needle removal in December or it can wait until the second stage of needle removal. If the wiring is done in January take care to not damage or rub off any new buds that may have formed from the December pulling.
February. Pines can be repotted starting in the middle of the month and begin to feed lightly. Do not pull needles or wire the tree at this time.
March: Increase feeding and look for Adalgia and spray as needed.
April: Increase feeding, spray as necessary.
May: Feed heavily; candles should have already lengthened and the needles are now growing out. In San Francisco the candles can be cut in late may or early June, depending on the weather. Usually in S.F., June begins to cool and cooler weather continues into July and August. Because of the cool summer weather the candles are cut earlier in the season. In the East Bay, south along the peninsula and in Marin the weather is warmer and the candles can be cut in mid to late June. Further inland, where the weather is even warmer, cutting can wait until mid to late July. Ultimately the tree will tell you the exact time to cut candles. Carefully study the new growth as it emerges.
There are two methods for equalizing the strength of candles on different sections of a tree. In the first method, candles are cut straight across the same height as the width of the candle base. The bottom third and inner branches are cut first; wait ten days before cutting the middle section; then ten more days before finally cutting the top section. This procedure strengthens the weaker sections incrementally by allowing them a head start over the stronger sections.
A second method for equalizing the strength of the growth is to leave stubs of the original candle on sections that are stronger. The presence of this small bit of the original candle inhibits the growth of new buds from the base. By carefully leaving differing amounts on different sections of the tree you can give the weaker sections an advantage. On the lower section cut the candles flush with the base; in the middle section leave a length equal to the width of the base and on the upper section leave about 1/2 inch of candle. Remove all the candles at the same time if using this technique. Monitor the emerging buds on individual branches and remove the stub if some of the branches are weaker than expected.
Since removal of candles causes stress to the tree, be sure that you understand the timing and method for their removal before proceeding. Remember that the tree must be very healthy and showing vigorous growth.
After decandling, fertilizing should be stopped for two to six weeks depending on the amount of heat you get in your location. Remove any organic fertilizer from the surface of the soil and do not use liquid during this time. New buds will appear 10 to 12 days after decandling. They will be very tiny and difficult to see.
In July or August resume feeding and spray as necessary.
September should bring a second spurt of growth and the new buds will begin to look like candles. If budding is very heavy remove the strongest of the growing buds.
October. Continue feeding.
November: Begin feeding 0-10-10 and continue throughout the fall. One or two fertilizer cakes can be used in place of 0-10-10, however do not replace them or add new ones through the winter. If you are using organic fertilizer it is important to renew the top soil in the fall. Rake off about the top 1/3 of the soil until all weeds and organic matter have been removed, add fresh soil to replace it. This allows the soil to breath during the wet weather and minimizes the chances of fungal infections and root rot. Trees can also be sprayed with a dormant spray during the winter, lime sulfur being the most common one. This will kill overwintering spores, insects, and insect eggs. Do not spray weak trees or trees that have recently had needles pulled or any other significant work.
In December the cycle begins again. It will take two or three seasons of careful observation to understand the process of needle pulling and candle cutting and how it improves the tree. Stick with it and you will be rewarded.
Interested in learning more? Check the Meeting page for upcoming programs and workshops about Pines.
For further reading on Japanese Black Pine care see these articles:
Adelgids (that white stuff on weak branches at the base of needles)