Japanese Black Pine Care Guide

The Japanese Black Pine, Pinus Thunbergii, is a very popular species for bonsai and can make a very powerful tree. Most times when you ask a non-bonsai person to think about a bonsai, it will be this species they imagine. 

They are relatively easy trees to care for and keep alive, although working on them can be a little stressful, for both the tree and bonsai grower, but over all they are not to bad.

I have been growing one from seed and you can see its development in my Japanese Black Pine Bonsai Progression.

What Is The Natural Habitat of A Japanese Black Pine?

Japanese Black Pines are native to Japan and South Korea and they grow in the coastal regions around the two countries. This type of coastal climate can be a lot milder than inland, so they do not get much frost exposure naturally. These trees will be intertwined with deciduous trees forests that also like this type of climate.

However, they can also grow inland and be found growing on higher land, up to heights of about 3300 feet. (1000m)

They will naturally grow to about 40m tall and can be recognised by their dark scaly bark that gives them their name.

What Soil Do Japanese Black Pine Bonsai Need?

Japanese black pine bonsai require a free draining soil mix. They do not like to be continually wet, but can handle getting a little dry at times.

However, I would not push your tree to its limits, use a soil that can keep the moisture levels pretty constant and make sure you are on top of your watering. I use my standard mix of Molar clay/Compost/ perlite and my tree has been happy with this.

It is going to be advisable to have some organic matter in your mix so that your soil can be a healthy environment to allow mycorrhiza to grow in the pot. This is a beneficial fungus that will coexist with the roots and actually make them healthier.

Basically the fungus helps the roots absorb nutrients more efficiently and in exchange the tree gives the fungus some food, and they both live happily together (or they have a symbiotic relationship, if you want to get technical)

If your soil is healthy mycorrhiza will find its way there. It will usually be in the organic matter already, and just needs to develop and grow as such. I wouldn’t worry about it too much, just let nature do its thing. You can “inoculate” your soil with products, but I don’t think this is necessary.

(For more info on soil read – A General Guide To Bonsai Soil)

How Do you Water A Japanese Black Pine Bonsai?

Japanese black pine bonsai are pretty robust trees and can handle a little drought in nature. However, I would not recommend you do this to them, as you can kill the root tips if they dry out, which will affect overall health and growth.

You should aim to keep the tree moist, but being able to do this will all depend on you climate and your soil.

If you have poor soil, that holds too much water, you are likely to get over watering issues. If this happens the needles will start turning yellow. (Needles can also turn yellow in the winter, or if there is a lack of fertiliser. However, most people are usually in control of this, so most times it is probably over watering in bad soil that is causing yellowing)

If you are using a good free draining soil it should be easy to keep the moisture levels right and then you just need to water your tree before it dries out and it should be more than happy.

(For more info you can read –How To Water A Bonsai)

How Much Sun Light Does A Japanese Black Pine Bonsai Need?

Japanese Black Pine bonsai should be outside in direct sunlight. They love the sun and should be given as much as possible.

If it is particularly warm and sunny, make sure you tree does not dry out, as they can use up more water when they are getting more sun light.

How Hardy Are Japanese Black Pine Bonsai?

Although Japanese Black Pines do live in slightly warmer climates than most other pines they are still hardy. They should be fine outside in most climates. They are Hardy to USDA Zone 6, which is a cold hardiness range between -17.8 to -23.2°C. (0 to -10°F).

Of course this is their ability in the ground, in a pot it may not be as hardy, but they should still be able to handle freezing temperatures without issue. For most us, we can leave them unprotected all winter, but I know some of you have terribly cold winters. If this is the case then you should protect the tree in an unheated greenhouse or shed.

They will need a cold period of winter, so make sure they are getting this.

(For more info you can read – Working Out How To Over Winter Bonsai Trees)

How Often Do You Feed A Japanese Black Pine Bonsai?

Fertilising a Japanese black pine bonsai will of course depend on what stage of development your tree is at.

If it is young and in development then you can pump it full of high nitrogen fertiliser. You want to get everything as big as possible at this stage. It is fine to get big needles and long branches at this point as it will all be thickening the trunk.

Once your tree is in refinement you will want to use a gentler fertiliser, usually below a nitrogen level of 10 to keep the growth more under control.

There is also a lot of discussion around when you should be fertilising. A general rule used by most professionals is to hold off in spring. Let the tree flush out and let the candles grow. Then when this starts to harden off, the needle size isn’t really going to change, so you can pump it full of fertiliser for the rest of the growing season and this should keep it healthy, but not make it grow too large.

A lot of people also fertilise into autumn and then generally stop at winter, this late application should give the tree the energy it needs to grow through the following spring.

(For more info you can read – Do You Need To Use “Bonsai” Fertiliser?)

How Do You Prune A Japanese Black Pine?

How and when you prune a Japanese black pine bonsai will depend on what stage of development your tree is at, which will try and explain here:

Needle Plucking

Firstly, all Japanese black pine bonsai trees will need needle plucked, at all stages of their development, as this will help to balance the vigour.

Pines are very simple. The more needles in an area, the stronger than area will grow. This means weaker or smaller areas may die off if you do not balance the energy by removing some needles from stronger areas.

This can be done from autumn through to early spring. (If your tree is in refinement you can do this when you are decandling)

You do this by removing needles from stronger areas so they match the amount of needles in a weaker area.

You need to find your weakest significant branch and roughly guess how many needs it has, and then pluck the stronger branches so they have about the same number of needles as this weaker branch.

You should also try and keep needles where you want back buds to form, so don’t just remove all the needles lower down on the branch, try and remove them at equal intervals along the branch length.

You should also try and remove any needles on the top of the branch or the bottom, this should leave more lateral, side ways facing needles, which is exactly where you want new shoots to form, rather than ones that are going to shoot right up,or point down.

Pruning Japanese Black Pines In Development

When you are developing a Japanese black pink you should be letting the tree grow wild and long.

However, buds will develop in a whorl pattern all the way around the diameter of the trunk.

This is like a T-branch, but instead of two branches coming from the same area, it can be eight. This can be a nightmare for inverse taper.

Although we want to get as much growth as possible, you need to be sensible and try and avoid inverse taper. You need to watch out for whorls of buds and branches and start thinning them out if they are getting a little out of control. If you see any signs of swelling in a cluster of branches you need to remove some from this area.

It is best to do any hard pruning when it is not flowing sap, which is usually towards the end of summer going into early autumn.

Pruning Japanese Black Pines In Refinement

Once you are refining a Japanese black pine you will need to start decandling followed by branch selection later in the year. There are a few different approaches, which I will go through here.

Decandling

In the summer you need to remove the new candles. You just cut them completely off at the base (so you are removing all of the new spring growth)

You need to remove the candles once they have fully elongated from, but before they open and the needles are showing. You need to time this right, if you wait too long you will miss the opportunity.  

A few weeks later you will see that where you have removed a candle, you will get new buds forming at the base of where the candle once was.

You also need to remember that cutting back to no needles is bad. If you just cut back to bare wood, or even to some small buds, this area will die. When you remove the candle, there should still be plenty of needles from last year just below where you have made your cut.

There are few approaches to how you actually go about decandling and it all comes down to trying to balance the new growth. Basically, once you cut the candles, they will start to grow back. The earlier you do this in the growing season, the longer the new buds will have to grow and become long …The later you wait, the less time they will have to grow back as they have less time until the end of the growing season … So really the longer you wait, the smaller the new growth will be as it has shorter amount of time to grow before autumn, so you can see how this may be useful in bonsai …although you also need to balance the fact that you only have a small window to do this who process, as i already mentioned, you need to remove them after they have fully growth, and before they have opened up, exposing the needles.

There are 3 different approaches you can take around decandling, so lets look at these in more detail:

-Staggering The Decandling Across your Collection

The first approach is just a general approach for when you have a lot of trees and you want to space the work out across these. You will see large nurseries doing this, staggering what trees they work on first.

With this approach you should start decandling your larger trees first, then go on to the medium size and finally they leave the small shohin trees until last.

staggering it like this means that the large trees will start growing back first and get the longest growing season, where as the small trees get the least amount of time to grow back, basically keeping them small.

I would say that for most of you reading this, you don’t have enough trees to worry about this problem. Although, I guess you could space out when you work on your trees even if you only have a few.

-Staggering Decandling On Individual Trees

The second approach is to stagger the removal of candles on individual trees.

With this approach you look at an individual tree and you then stagger when you remove the branches across this tree.

Basically you start by only removing all the small and weak candles. This will let them start to activate and grow. Then 10 days later you come back and then remove all the medium size candles from the tree, and then 10 later you come back and remove all the strong candles.

The idea is that now the weak buds have had almost 3 week weeks to start growing, so by the time the strong areas start growing again, they will all be about equal size. This should then balance the tree out and all the new needles should be about the same size.

This is obviously a little hard to keep track of if you have a lot of trees but this is used a lot by people growing black pines.

-No Staggering

lastly, the third approach, which is also common in a lot of Japanese nurseries, is to not bother staggering anything.

Some nurseries got a bit sick of trying to track what has been done to different tree sizes and what has been done on what individual trees, since they have so many, so they decided to not stagger any cutting. They just remove all the candles at once.

They come in and remove all of the candles at the same time and just let whatever buds grow, to grow.

I would say this is probably done in nurseries where they are just trying to grow a lot of starter stock and not to worried about refinement. I would imagine you will have a lot less trees and could easily track what you have done, or not so you may prefer one of the other approaches, but this is still an option if you want to do it this way.

My Approach

My Japanese Black Pine bonsai is still very young and I have not had to prune it much yet.

Basically I removed all the candles at once during its first pruning. This was simply because they where roughly all the same size. When my trees gets older I will probably find some areas are weaker than others and I will remove the weaker candles first, then come back after a week or 10 days and remove the stronger ones.

I only have one pine, so I can’t really work on my larger trees before my smaller ones …because I only have one!

There is no right or wrong way, Japanese nurseries do it differently, so you can too. You need to decide what approach is right for your trees and go with the method that makes most sense to you.

Branch Selection

Once you decandle, the buds are going to start developing where you cut. As I’ve said before, pines grow in whorls. Which means you will not just get 2 buds, you might get 3, or you might 5 or more all in the one spot

At the end of the summer you need to come back in and see what is going on. You need to check every branch where you cut a candle and see what new shoots have formed. You then need to remove any extra ones. You only want 2 shoots at any one spot, so if you have more, you need to pick the best 2. keeping any more than this is going to cause reverse taper and ugly knuckles, so thin out the new shoots so there is only 2 in one place.

You are best to pick two that grow out to the side. Ones that grow up and down should be avoided. However, you can still keep these, but you will need to wire them into a better alignment.

If you can pick lateral shoots, it will stop you having to wire as much.  

Repotting A Japanese Black Pine Bonsai

You should repot Japanese black pine bonsai in early spring, once the risk of frost has passed.

You will see the new candle buds starting to swell, which means it is the perfect time to repot.

A pine gets its energy from its roots, so you cannot be as aggressive with them compared to a deciduous tree.                                                       

You should only remove about 30-50% of the root mass. However, this depends all depends on how healthy it is as well as what stage of its development it is at, basically you should always err on side of caution with the roots. Often less is the better option.

If you are moving from the development stage into the refinement stage you will probably go a little harder on the roots, especially if it is the first time you are going into a bonsai pot from a nursery pot. In this instance you may cut off more roots than usual (around 50%)  This is pretty dramatic and of course risky, but at some point you need to reduce the root ball down to fit into a smaller pot.

When your tree is refined you are going to fewer roots off. Really you should just remove the bottom matt of roots to give it enough space in the pot.

You should also not remove all the soil and you should certainly not wash the roots. This is going to get rid of the healthy mycorrhiza, which you really do not want to lose.

You should aim to repot around every 5 years once your tree is in a refined state. As the roots are the real energy engine of the tree you want to avoid messing with them as much as you can, this is why you should really wait as long as possible in between repots. However your soil, pot size and climate are all going to play a factor in how often you need to repot.

(You may find reading – A Guide On When To Repot A Bonsai helpful)

Once you repot, aftercare is really important. You need to give the tree shade for 2 or 3 weeks and avoid wind as well. Too much sun and wind can cause too much transpiration and as it has damaged roots it will struggle to get water up into the tree until until it fully recovers.  So you need to avoid water loss by keeping it sheltered until it heals.                              

Wiring A Japanese Black Pine Bonsai

You will need to wire your Japanese black pine bonsai tree as it will be very difficult to get a good shape form it naturally or through pruning alone.

You can design your Japanese Black Pine any way you want as they work well in pretty much all traditional styles. However, you need to remember that pines will look most natural when the branches are wired down and outward, as this is how the mature trees grow naturally.

(For more info read – Why Do We Wire Bonsai?)

What Is The Leaf Pattern Of A Japanese Black Pine Bonsai?

A Japanese black pine has needles. They are clumped in pairs, so are called a two needle pine.

They are also evergreen, so they will stay the same all year round.

What Pests Does A Japanese Black Pine Bonsai Suffer From?

The black pines are usually quite disease and pest free. They can still be attacked by spider mites and scale, but if your tree is outside and healthy, it shouldn’t really have many problems.

Can You Propagate A Japanese Black Pine Bonsai?

You can only grow more Japanese black pines from seeds. they will not propagate through cuttings or air layers.

The only way to start an established tree is buy some nursery material, or dig up a tree from the wild.

What Is The Growth Rate Of A Japanese Black Pine Bonsai?

Given the right conditions a Japanese black pine can grow quite quickly. However, in the bonsai world these trees will grow quite slowly, they can take a long time to develop but they are certainly worth the wait.

They do usually take a lot longer to develop compared to a deciduous tree, but the end results are worth the effort.

Should You Get A Japanese Black Pine Bonsai?

Japanese Black Pines are great trees, but probably not ideal for a total bonsai beginner. You need to be careful with the roots, as well as understand the slightly complicated pruning procedures, which can be a little too much for a beginner.

However, if you are patient and dedicated, a beginner could slowly grow one from a seed and then work on other easier deciduous trees in between.

So far I have really enjoyed mine so I would suggest you add one to your collection too.  You can read more about Are Japanese Black Pines A Good Trees For Bonsai?