By Thomas J.

Repotting the Japanese Black Pine is actually no different than any other tree repot in the sense that it is something that is needed and that the right timing and soil are used to get the tree to respond to its pot acclimation in a healthy and positive way throughout the year. It has recently been noted by those who have been working with Japanese Black Pine for a good many years, that it helps very much to repot on a yearly basis with these trees or at least every other year rather than going by the old school method of waiting sometimes up to five years for older trees.

In my recent purchase of a few Japanese Black Pine that had probably not been repotted in a few years, the soil had hardened to almost brick like consistency and the tree, even though it still looked good, was weakened considerably in that it wasn't back budding the way it should.

Japanese Black Pine should always be kept as strong as possible because they have to go through a lot of stress during the decandeling and needle pulling at one of the most stressful times of the year, mid summer. The repot will encourage new finer feeder roots and together with the new fast draining soil, will give it a boost just before the new candles begin to open in the spring.

Repotting here in the U.S. and especially here in Texas is right around mid December to early Feburary and usually no later. Other northern states might be able to wait a bit later. As with any repot, keep an eye on overnight temps and see to it that you take every precaution to keep the repotted tree from freezing temps as this will most likely hurt the new fine root system that will just be developing.

You'll notice the root rake that was used and how much was needed to take off of the old compacted soil.

You don't have to be afraid to scrape off dilligently if the root ball is really compact because it needs to come off one way or the other. You may need to scrape a small layer off the top also. Now when I say dilligently, I don't mean to start tearing roots without any concern, but being too gentle might not get you where you need to be either. If you have been doing repotting of trees for a number of years you'll already have the feel for it. If you haven't, just use a little caution and common sense toward this aspect of bonsai culture and you'll be alright.

It's a good idea also to have your pot ready to go with anchoring wires and your prepared soil nearby.

A good soil mixture for JBP is:

1 part akadama
1 part lava
1 part pumice

Be sure to filter out the fine particles from each with your soil sieves.

Remember the first tree above with the compact soil, well here it is about six or seven weeks later with its new candles all a glow. By the summer decandeling she was ready and waiting.

And how about the other one where I had to take quite a bit of root off in order for her to breathe in that narrow semi cascade container. Here she is with her candles all grown out and begging to be decandeled. Notice how healthy she looks all due to a good repot and a good soil change.

Here's a recent picture of the same tree after its fall work.

A word of caution if your Japanese Black Pine is an older specimen with rough flaking bark such as the Mikawa cultivar as seen here.

Do not grasp the tree at the base where you will stand a good chance of tearing off the delicate bark, but rather hold the tree farther up the trunk by the branches. This will insure that your trunk at the base will continue to look old and aged without any tear out.

Well I hope this small article will be of some benefit to those who may be doing their first Japanese Black Pine repot this year. By the time you read this article it will almost be time to repot for some, or at least time to get those new pots and soil mix ready for the necessary task that lies ahead.