Pruning Pine Bonsai Trees [Methods and Correct Timing]

It is best to start one of the most popular techniques in pine shaping right in the middle of summer. 

Pruning pines in summer is more beneficial than doing so in winter. To increase light penetration and reduce the size of the pine needles, you can use shears or scissors to prune them in the spring. This is especially useful for black pines with long needles and strong regrowth.

Japanese five-needle pine bonsai

Read further to learn the correct methods to prune pine bonsai and when to prune them throughout the year.

Pruning Pine Bonsai

Pruning for needle removal involves removing all or part of the pine’s newly formed candles. This task can only be done if the tree is strong and has not been re-potted in spring. Also, the needles must be fully formed and mature to be successful. 

Do not prune immature needles.

The period best to prune pine bonsai can vary depending on the climate. It may be from early July through early August. There is also the possibility of new growth becoming too weak or getting off to a bad start. To restore strength to the tree, it is necessary to plan how fertilizer will be applied in the autumn. 

Pruning weaker trees or those with shorter needles should take place in July. Black pines that have large new shoots should go in August. 

Summer pruning is a great way to stimulate a second growth phase (after the spring), and it will reap the benefits of the autumnal increase.

Pruning Methods for Pine Bonsai

Pinus thunbergii
Pinus thunbergii Bonsai

Use fine scissors that have sharp edges when pruning. Cut back long, new branches by cutting them off above a new shoot. 

Pro tip: the tree’s reserves will be exhausted by the second growth period. However, this can only happen if fertilizer is not applied before autumn. 

Before deciding on the shape of your bonsai, study the tree carefully and consider the species’ natural form. To achieve an impression of age and reality, observe the way mature trees of the same
kind grow in their natural setting.

Virginia State University “The Art of Bonsai”

This works well with long needles (Pinus Thunbergii, black pines) and medium-sized needles, such as Scots pine, red pine, and mugo pine. 

For small-needled trees like the Japanese five-needle Pine, it is important not to weaken the tree by doing the same pruning over and over again. 

Image Credit – New Mexico State University

Others will need to consecutively reduce the needle size for at least three years. There is still time to remove the old needles if you haven’t done so by last autumn. 

You should not attempt to remove them by hand. This could lead to the risk of removing the buds at the base of the sheaths that will be needed to form the new branches. 

It is important to know your desired outcome, depending on which tree you are working with. You need first to understand the species and the stages of shaping.

Then, consider the overall shape of the tree. Because styles tend to be more important for certain areas, it is important to determine your intended outcome.

Summer pruning, in any case, is an operation that forces the tree’s ability to grow new needles. Without them, it will die. Some trees are not recommended to be pruned every year. 

It is not advisable to prune weak or sick trees or those with mature ramifications. 

You can also use pinching to balance out the growth of these trees. Pruning to reduce needles is not the only way to create fine ramification. However, it allows the process to be expedited and done in one season. 

After pruning is complete, do not overwater or apply fertilizer before autumn. The new growth will begin at the end of summer so place the tree in a sunny location to encourage the tree to produce buds in the pruned areas and the inner parts of the branches.

The needles will develop naturally after the candle is removed.

The number of candles is thinned by 1/2 to 2/3, and those that remain are shortened.

Harvard’s Bonsai and Penjing Collection Care

The new growth is extended in June and leaves a space between old needles and new ones.

The needles become hardened and almost mature in July. Then, cut in the middle of the space.

Cut back any points that are too long, as well as any new shoots which are too thick or poorly placed. Radially trim the branches’ points and the apex. This is the most active and busiest area of the tree.

You can finish the tidying task by cutting the twigs and quickly plucking the needles. To encourage inner buds, cut back excessively long twigs. It is important to trim and thin out areas exposed to the sun, particularly at the apex. Summer pruning is an act that exhausts the tree’s reserves. It can also be used to control bud growth. This is the best way for you to balance the vigor in different areas of your growth.

Pruning is not about replacing the needles. This is the only way to reduce the needle size. It is a safe technique that can be used on all pines.