Care and propagation of a Black Pine Bonsai
Black Pine - Pinus thunbergii - Arguably the most popular species used for bonsai today, the Japanese Black Pine makes a n excellent choice for a bonsai. The size and shape of Japanese Black Pine in nature may reach a height of 50 feet and a spread of 20 to 35 feet. The exceptionally dark green, five to seven-inch-long twisted needles seen on a garden verity will shrink down to as short as 1” on a mature potted show quality specimen. Black pine is a native of Japan . It prefers but does not insist on colder climates. When grown in the warmer climate of Southern California they need special care in the summer months.
I have over a dozen black pines varying in height and age from 2003 seedlings to 50 year old specimens that are only 24” tall. Formal upright, slanted, informal upright, Bonjin, cascade, any style you desire can be achieved with a Japanese black pine. I even have a 7” tall 10 year old Japanese white pine that was grafted on a black pine root system.
The one thing all black pines have in common, big or small young and old is they do not like extreme heat, especially in the area of its roots. This makes it a little tricky where I live so I set my benches up so the plants would get about 4 hours of full sun and good air circulation each day. The picture above shows some of my partial sun benches. I also turn the tree from time to time and trim the inner needles so that light reaches all parts of the foliage. The plants that I have wired never get direct sun light, these are kept under my patio cover to filter the direct sun.
Pruning and wiring your pines
Prune during the early growing season. Begin pinching at the end of spring when the buds have matured. First pinch the undesired weak buds and a week later pinch the undesired strong ones. A couple weeks later selectively remove buds in the weak areas, leaving only the biggest and strongest. In areas with strong growth leave the weak buds, removing the biggest and strongest. Remove buds growing from the bottom of branches, leaving only lateral buds.
Propagation of Black Pines
Black pines may also be grown from seeds sown in sand in early April. Seeds should be soaked in water for two days to hasten germination. Black pines may also be propagated by grafting and from cuttings however these methods take a considerable time and lots of patience.
Repotting: Repot in Spring before the buds begin to swell. We use our own soil mix "Perfect Drain Professional" bonsai soil for medium and large pines and "Perfect Drain Shohin" for small plants. If you cannot afford professional soil or just wish to make your own a mixture of coarse sand, clay and peat works well or you can replace the sand with agricultural pumus. Don't under pot a black pine, Choose a container large enough so the feeder roots do not dry out and die at the end of a summer day.
To take up nourishment, pines need to have a special type of fungus in the soil around their roots. For this reason is never advisable to completely wash off all the soil from the roots of a black pine unless the tree is very healthy. This fungus appears as a white, stringy material. When repotting, make sure some of this helpful fungus is included in the new soil mix. Once established fertilize your plant with an organic fertilizer.
Pests and diseases: see Pest Control