The Pine is an evergreen tree with sharp pointed leaves, called needles, which stem from a scaly sheath in bundles of two, three or five. The seeds are contained in a cone that usually ripens the following year. The pine is frequently used for Bonsai because, being evergreen it looks well throughout the year and it also has the added quality of longevity. The most commonly used variety is the Japanese White Pine closely followed by the Japanese Black Pine. Due to the limited availability of these species in the United Kingdom, other native Pines have become more popular. These include the Mountain Pine and the Scots Pine because they have beneficial features for Bonsai, which are short needles and compact growth.
Pines, which are commonly used for Bonsai are:
Botanical name Common name
Pinus Parviflora Japanese White Pine
Pinus Thunbergii Japanese Black Pine
Pinus Sylvestris Scots Pine
Pinus Mugo Mountain Pine
Pinus Densiflora Japanese Red Pine
Pinus Nigra Black Pine
Pinus Cembra Arolla Pine
Five needled Pines
The most commonly used Pine is ‘Pinus Parviflora’ which many enthusiasts do not know how to care for properly and many beautiful trees are ruined although the grower has the best intentions. What we hope to achieve in a Pine Bonsai is a tree with good overall shape, trunk taper and well-defined pads of compact growth with as short a needle as possible. Good overall shape and trunk taper are achieved over the years by properly executed pinching and pruning techniques that are described below. If these techniques are carried out properly, its end result will be a healthy and vigorous tree with compact pads and short needles.
The best way to explain how to pinch and prune a Pine is to go step by step through the growing seasons showing you what to do and when, illustrating each step with a set of diagrams. We will begin in the Autumn.
Autumn is a busy time for Pines as far as Bonsai is concerned. The main tasks are removing old needles, Autumn pruning and bud removal. Before explaining these, it is important that you know the strong and weak parts of the tree, as these techniques are applied to try and achieve a balanced growth pattern. If a Bonsai is let grow freely, strong areas will grow stronger and the weak ones will weaken even more. Generally the upper part that receives more sun and air is the strongest zone. That means that in a short time, the tree would be weak in the interior and lower branches. Therefore it is crucial that we control the growth by weakening the strong areas to give energy to the weak.
The first step in achieving equal strength along a branch is the removal of old needles in the middle of September when the new needles have matured. A Pine will automatically cast its oldest needles in the Autumn in preparation for the new buds growing in the Spring. We help the tree along by removing even more of the needles than the tree would naturally have shed, causing more vigour. These needles are removed by cutting them off with scissors leaving 1/16th of an inch or so of the base. By doing this, you are leaving a dormant bud in the sheath that might grow in the Spring if successful back budding is achieved.
WEAK ZONE MEDIUM ZONE STRONG ZONE
very few removed removed Old needles removed Old and new needles
Leave about 3-4 mm
When removing old needles act according to the zones of vigour: do not remove any needles on a weak branch (wait for them to fall by themselves); remove only old needles on the branches of medium strength and, on the strong ones, in addition to the old ones, remove some of the new needles.
Weak Branch Strong Branch
The right time to remove buds is the middle of October. If all the buds were left untouched, the tree would grow freely, losing its balance of strength. The general practice is to leave only two buds on each shoot. On the strong branches remove the strong buds, and on the weak ones remove the weak buds. If it is desirable to let any branch grow or thicken, do not remove any buds.
Pruning is done in the Autumn to regulate the balance of the tree’s energy, forcing strength into the interior and lower branches. Pruning is only done in strong areas.
The next step in developing a Pine Bonsai is in Spring, when the buds swell to become candles; (forming branches) these candles must be pinched to slow down the strong shoots. Candle pinching is usually done at the end of April when it looks as if the new needles are ready to open. Using your fingers, pinch out either 1/2 or 1/4 of the initial length of candle.
Pinching of Candles
The first step is to pinch back the longest candles (that will logically be in the strongest areas) and a week later the rest (in the weaker areas). As a general rule, on a tree already established, leave only 1/4 of the candle, but on a tree undergoing initial shaping pinch back only a little. Warning! Do not remove the whole candle from a five-needled Pine. Always keep in mind the planned development of the tree, since the point at which the candle is cut off is where the new buds will open the following year.
Two needled Pines
The most commonly used two needle Pine is Pinus Thunbergii, but the most available are Pinus Mugo and Sylvestris. The majority of training techniques for a two-needled Pine are the same for one with five needles, but there are a few small changes that have to be made because the two-needled Pine is more vigorous. The most important one is not to pinch the strongest candle first (as done with a five needled Pine), but to take a little off the weak shoots first and then, about a week later remove 2/3rds of the medium strength shoots, and a week after that remove the whole candle from the strong shoots. (This can be done with two needled Pines) due to its vigour it will then go into a second budding. By the end of July these should be well formed. At this time, remove the unnecessary buds. If done too late, budding will be too strong and the tree will bud weakly the following year. To know which buds to remove, refer to the paragraph on bud removal mentioned previously in this handout.
After you gain more experience with your two-needled Pine you might find the following tips helpful. Remove more of the needles in the Winter than you would on a five needled Pine. i.e. leave only three pairs of needles around each shoot of strong vigour. This procedure maintains and invigorates the weak parts, forcing the strong ones to bud slowly. It is also good to let the candles mature slightly more, before pinching, than you would have let them on the five-needled Pine, but always pinch before the needles open out. Also, depending on the species of tree you can pluck the needles out of the sheath instead of cutting the needles with scissors, this can be done with Pinus Thunbergii.
Watering and Feeding
Watering is an art that you master with experience. You have to adjust for changes in the weather, needs of the tree and because one potting mix may be more porous than another. Pines must not be watered too much or all your pruning and pinching will have been for nothing, as over watering makes the needles grow too long making your tree lose shape and balance. It is best to water thoroughly when you do, but remember that Pines need to be somewhat dry before the next watering.
For the majority of Pines, you feed them from early to late Spring and from the end of the Summer to late Autumn. You do not feed in the Summer because this also increases the needle length.
Repotting and Wiring
A Pine can be repotted in Spring or early Autumn, every 2-3 years for young specimens and every 3-5 years for older ones. A popular potting mix is 50% soil or ‘Akadama‘, 10% peat, and 40% grit or equivalent material. This is only a guide as everybody has his or her own special mix.
Wiring is best done in Autumn – Winter after eliminating any unnecessary branches. Keep a close eye on wire in the Autumn as this is when a Pine thickens the most. It can take many years for a Pine’s branches to set in position, so constant rewiring of branches is necessary.
As you can see, Pines are probably the most complicated of all the trees that are trained as Bonsai. This care guide was made to help both the beginner and the enthusiast, but it by no means covers every detail on the subject. Members should expand their knowledge by reading any relevant literature available to them, and if in doubt, ask!