Creating a Slanted Black Pine Bonsai from Seed

Creating a Slanted Black Pine Bonsai from Seed

Growing Japanese Black Pine Styling

Many bonsai enthusiasts share a common interest - starting pines seeds to grow some trees from scratch. Overall, it’s a relatively simple process that involves a lot of watering, fertilizing, and waiting for months until key time periods when critical work must be done. The hardest part of this endeavor is simultaneously being patient and keeping on top of the key creative tasks. 

One of those creative tasks is selecting a style. It's when the seedling is two years old that it's treatment will largely determine it's ultimate style as a bonsai. I'm going to step through the process of making a slant style bonsai tree that is roughly 20″ tall. 

A black pine started from seed in the spring will reach somewhere between one and four inches in height in the first year.  This seedling cutting technique, outlined by Jonas Dupuich of Bonsai Tonight, slows the tree down only slightly. At the end of the first year there is normally a nice bud at the top of the tree, already showing the characteristic white fuzzy covering. At the base of the seedling there may be a few small side shoots; nothing more than a couple immature needles at this point. The tree may have a few pairs of normal needles or none at all.


Japanese black pine seedlings. Left: 6-month old seedlings are 2-4″ tall, Middle: 18-month old seedling is approximately 12″ high, Right: 18-month old seedling that was decandled in June of the second year (mame anyone?)

If the seedling cutting technique was used then the side buds at the base are likely less than an inch from the first fork in the roots, the spot where the tap root was cut. Despite expectations to the contrary, the seedling cuttings seem to typically put out only 1-4 roots from the cutting site. This isn't a problem; the branching of the root structure will develop further along with the rest of the tree.

In spring of the following year, when the tree is a little over a full year old, the bud will begin to elongate and the tree will quickly attain 10-14″ in height. The majority of the growing season then is spent growing the needles and setting the strong whorl of buds at the top of the young tree. The tree will build strength through the fall and winter making the buds larger and the following spring’s elongation more vigorous.

The buds that set during the second summer are the first true whorl on the tree. If all the buds are left on and the tree is very vigorous it can result in reverse taper at the node. Remove all but one of the side buds starting in August or September using either your fingers to twist them off or scissors to cut them. Repeat this process each fall for nodes that you want to keep as part of the trunk.


Twist off the side buds at the whorl in early fall to prevent reverse taper at the node.

Buds removed. The large bud is the next year’s trunk extension; the smaller bud will be the branch. Selecting which bud remains can be done based on the direction that you want a branch to go. You can twist the young trunk to reposition the bud to the desired side later.

In my experience, and that of other California growers, the end of the second growing season is usually the first opportunity to wire the tree, which is the 20 month mark. In other regions, you may be able to wire and shape a tree as young as 13 months, in March of the second year. 

In the winter after the second growing season take the two-year-old tree and remove it from the small growing container to comb out the roots and trim them. This process will increase the number of roots near the trunk. Cut the roots back to a small circle of radial feeder roots, about 2-3″ across. Wrap a wire around the trunk, leaving a tail sticking down through the roots. Use the wire to bend the base of the trunk as close to the roots as possible. The space between the roots and the bend should be less than 1″ so coil the wire closely enough to be able to bend the trunk easily. Add some small gentle movement in the trunk, letting it generally head in one direction; in my example the trunk is bent to the right.

Figure 1. Representations of first, second, and third year Japanese Black Pines. The scale bar at left shows roughly a twelve-inch height, which is what a healthy seedling typically achieves by mid-summer of the second growing season.

The 2-year-old shown in Fig 1-2 is wired and bent to make Figure 1-2a. Pot the wired and bent tree into a larger container, preferably a colander or pond basket that will air-prune the roots. Heavy fertilization, watering, and good sun are required for good growth. By early summer of the third year the tree will have a trunk extension that is another 10-15″ in height. The smaller branches that are lower down will elongate as well but to a lesser degree. In June, or around the time you typically decandle Black Pines in your climate, remove the top 10-15% of the new growth; remove the whorl and node and force the tree to create needle buds below it as shown in Figure 1-3. Wire the third year growth to add movement. On very strong trees the needle buds will form new extensions while on weaker trees buds will set but no new extensions will form after the terminal bud is cut.

If the tree has been left well into the third year of growth without wiring the trunk it may be more difficult to style the tree. The trunk on a vigorously growing three-year-old will have enough wood in it to resist easily adding smaller movement. Use larger wire and try to make multiple bends to make the trunk more interesting. Some movement is better than none!

Figure 2. The fourth year of growth. In the spring all the new growth will elongate. The buds and short growth formed after cutting back in the third year will cause more diffused growth. Decandle much of the new growth, leaving one branch as a sacrifice branch to continue growing, marked above with an A and arrow. End of year 4 shown on the right: After decandling, the summer growth on the branches will be shorter while the sacrifice branch will set a strong bud for the following spring. You can decandle the lower branches or not depending on how vigorously they are growing.

In this example, the fourth year is spent both starting the sacrifice branch again and controlling the growth of the other branches. Determine the cut point of the sacrifice branch with some certainty. The cut should be to the side or back and the cut should be positioned so that it can be made vertically or at a steep angle, but not horizontally. Depending on growing conditions the 4th year growth may be very vigorous or more slow after removal of the terminal bud in the third year. If it is very vigorous and even throughout the tree, then decandle most of the branches, leaving only one that you plan to use for the sacrifice branch. If the growth is weak, or one branch is already naturally taking the lead, then skip decandling in favor of creating longer branches.

Keep in mind at all times that this process is primarily creating a trunk and the placement of the key primary branching. Considerations present during the refinement stage are not of primary concern during this growing stage. During the growing stage make decisions that will maximize the wood growth in the trunk while keeping the branching small but healthy and viable for use later, after the sacrifice is removed. The standard pine care cycle is only a reference during the growing stage. The techniques can be used similar to an established tree; but they should not all be used as this would prevent the tree from increasing in girth.

Figure 3. Year 5 and beyond. Once the sacrifice branch is established, control the growth of the other branching to keep it small while allowing the sacrifice to grow as strongly as possible.

During the 5th year the sacrifice branch should again be allowed to grow unchecked. The other branching can be pruned back as needed to control vigor or be allowed to grow to create the primary branching and apex. Pruning and decandling will give different results and should be used to best advantage. While decandling will reliably set 2-5 new buds at the site, summer pruning behind the node can lead to more compact growth where needed.

In the second and third year, the lower and middle trunk sections were wired to create the height and establish the sacrifice branch in my hypothetical composition. At the end of the 5th year it’s a good time to revisit the design and wire any branching that you will keep. Remove any branches that are not needed for your design. Wire the remaining branches to move the strong growing tips to a horizontal position. Remove only the needles that are on the resulting bottom of the branch, leaving needles on the top and sides of the branches. When the branches are later decandled, or even sometimes spontaneously, new buds will form from between some of the remaining needle pairs.

A black pine branch in late summer. The decandling site at right is producing three strong buds. Equally importantly, the needle I retained on the top of the branch from two years ago, at left, is also producing a bud. This type of bud is frequently more useful than the buds that result just from the decandling sites.

Needle reduction is a refinement technique that should be used sparingly during the growing phase. Thin needles where needed to increase light penetration, but err on the side of too many needles since the young tree will have fewer branches than an older tree.

After the fifth year continue growing the sacrifice branch out. The side shoots of the sacrifice branch can be removed to avoid shading the lower branches where needed. Decandling of the lower branches should be performed only sparingly. Pruning back the lower branches during winter to a side bud will weaken the branches less relative to the sacrifice branch than decandling during the summer.

Where the sacrifice branch is too vigorous and the hormone from it is causing the lower branches to get weak, remove the central leader and 1-2 years worth of the top of the branch. Leave a strong side leader in place to take over as the new sacrifice if additional trunk girth is still desired.

When the time comes to finally remove the sacrifice branch, which may be as soon as years 8-10 for medium size trees, cut back in stages to allow the tree to adjust to the changes. Removing the sacrifice all at once can cause the remaining branching to become too vigorous, or excessive sap flow can cause the needles to be long, weak and yellowy. Remove about 50 percent of the sacrifice at the first pruning. Then during the following summer decandle the sacrifice branch tips along with the other branches and remove another portion. Depending on the size of the sacrifice, take 2-3 years to completely remove it.

We sell Japanese Black Pine seeds in packets of 40 here!

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