For many bonsai enthusiasts, Japanese Black Pine and Japanese Red Pine are among the most rewarding species to grow. Their vigorous growth, ability to back bud, and rugged bark make them outstanding bonsai subjects—but they also require a different approach from single-flush pines such as Scots Pine or Japanese White Pine.

A recent talk at the June club meeting by Neil Hutchings explored the principles behind growing and refining these trees. Here are the key takeaways.

Understanding Double-Flush Pines

Japanese Black Pine (Pinus thunbergii) and Japanese Red Pine (Pinus densiflora) are both double-flush pines, meaning they naturally produce a second flush of growth during the growing season.

This adaptation evolved in Japan’s coastal regions, where typhoons frequently strip trees of their foliage. The ability to produce a second flush allows the trees to recover quickly after storm damage.

By contrast:

• Japanese Black Pine is the most vigorous.
• Japanese Red Pine has medium vigour.
• Japanese White Pine is slower growing and is a single-flush species.

Feed early to build strength

Unlike single-flush pines, Black and Red Pines should be fed heavily from late winter, as soon as the buds begin to swell.

At this time of the year the goal is simple: build as much energy as possible before summer.

Although this encourages long candles and needles initially, those shoots will later be removed. The resulting second flush naturally produces shorter, finer growth, making the early feeding worthwhile.

Summer shoot cutting

The key summer technique is often called candle cutting, although “shoot cutting” is arguably a more accurate description.

For Japanese Black Pine, this is typically carried out around Late June to early July. Japanese Red Pine is usually worked one to two weeks earlier. Every current season’s shoot is removed, leaving a small stub behind.

An alternative method in the past was to cut the weaker shoots first, medium strength 2 weeks later and the strongest shoots 2 weeks after that. Because the longer stub takes longer to die back, the strongest areas bud later, helping to balance vigour throughout the tree. This tends to be used less these days though.

Resist the urge to thin too soon

After shoot cutting, multiple new buds appear—often between two and ten from each cut point. It is also important to stop feeding at this time for 4-6 weeks to encourage a short needle length on the new buds.

One of the biggest mistakes is selecting the final buds immediately. Instead, allow every new bud to grow throughout summer. Removing excess buds too early concentrates all the tree’s energy into the remaining shoots, producing long needles and defeating the purpose of summer pruning.

Bud selection is better left until autumn, when needle length has set .Once the needles have hardened off their length will not change.

Balancing vigour with needle density

A pine distributes energy according to the amount of foliage present. This means needle removal becomes one of the most effective tools for balancing strength throughout the tree.

Reducing needles in the apex encourages the lower branches to remain vigorous, preventing the common problem of weak lower growth.

Many growers simplify this process by maintaining roughly the same number of needles on each branch, allowing the tree to distribute energy more evenly.

Developing strong trunks

Create movement in the trunk begins while the tree is still young. Wire should be applied while the trunk is thin and flexible, introducing bends that will soften naturally as the trunk thickens. Alternating the direction of spirals rather than using one continuous twist creates a far more natural appearance.

Sacrifice branches and leaders

One of the quickest ways to thicken a trunk is by allowing a sacrifice leader to grow unchecked. However, this requires careful management. Leaving the sacrifice for too long can reduce taper, while removing it too abruptly can shock the tree.

A gradual reduction—either by cutting back in stages or partially severing the leader before final removal—helps reduce the risk of dieback.

It’s also important to reduce watering after removing a large sacrifice leader, as the tree’s water demand drops dramatically.

Pot size matters more than you think

One surprising lesson concerns container size. Contrary to popular belief, moving a young tree straight into a large pot does not necessarily speed growth. Progressively potting up through slightly larger containers often produces much faster development because the roots colonise the soil more efficiently and the growing medium dries at an appropriate rate. Healthy roots equal stronger growth.

Repotting

For vigorous Black and Red Pines, avoid combining heavy root work with summer shoot cutting in the same season. Allow the tree to recover fully from one major operation before asking it to perform another. Many growers now find early autumn repotting provides reliable results in the UK’s increasingly unpredictable spring weather.

Cones aren’t always a problem

Conventional wisdom often suggests removing cones to conserve energy. In practice, healthy pines generally tolerate cones well. In fact, branches carrying cones may actually thicken more quickly because of the additional weight they support. Unless the tree is weak, cones are rarely a cause for concern.

Every garden is different

Perhaps the most valuable lesson from the talk was that bonsai techniques are rarely absolute. Advice found in books or online reflects the climate, feeding regime, humidity and growing conditions of the person giving it.

Experimentation remains essential. Observe how your own trees respond, refine your techniques over time, and allow your growing environment to guide your decisions.

Final thoughts

Japanese Black and Red Pines reward patience more than almost any other bonsai species.

Success comes from understanding how these trees naturally grow: build strength early, prune at the right time, balance vigour carefully, and develop structure gradually.

With consistent seasonal work, even young material can develop impressive trunks, refined branching, and the rugged character that makes these iconic pines such enduring favourites in the bonsai world.

Many thanks to Neil for the informative talk.