Repotting 3-4 year old Japanese Black Pines

A short article for those looking into the repotting of JBP:
Throughout the year there will be updates with relevant content about repotting, bare-rooting (seedlings), removing compacted soil, root pruning and timing specific technique aimed at helping people who are new to JBP.

You may find the timing of repotting to be a point of contention, so I'm just going to share some experiences and successes that I've had in gauging where a JBP is at in it's growth cycle, and then applying this towards repotting. For the purpose of this article I'm just going to focus on JBP however I'll tell you that I've repotted many trees during months that are considered "early" and "late" this year, and I'll get into that later.

The pines you see here were repotted in the following months: November '16, December '16, January '17, February '17, March '17 and April '17. There are over 50 JBPs on my benches and they are all in different stages of development and seasonal growth, so they required work to be done at different times and for different reasons. If you ask Ryan Neil "when should I repot" he'll ask you "why do we repot?", if you ask him, "when should I apply fertilizer and how much?" he'll ask you, "what are you fertilizing for?"


I was able to take advantage of a relatively mild winter coupled with extraordinary rain fall to get it all done, and I was able to spread the work out over 6 months because I let the trees tell me when it was "ok" to repot.

If you have a large garden with specimens from various sellers and climates it's likely you've noticed that trees within the same genus are not on the same seasonal growth schedule, unless you started a batch from seed - which many still show great variation. Some pines will wake up early, some late. Some will go dormant late, some will not go dormant at all. When you can identify, I should say verify, where a tree is at you can then apply whatever technique is appropriate. This is a fundamental bonsai concept that is widely written about, but mostly I see discussion about seasonality rather than a tree's internal clock. Sure, it's safe to say spring, repot in spring and you'll be fine. But in Santa Cruz we have what I consider to be a challenging growing season because it is so long and there are not obvious climatic changes between the seasons. I find my trees get 'confused' and begin growing out of season, which means they've spent energy when they should be sleeping. When this happens, spring may not be the best time to repot and fall becomes a better option.

Spring in Santa Cruz can start as early as the beginning of February if we were to consider temperatures and not photo-period. This first image set is taken April 1st: A 3 year old tree with no observable root growth or candle elongation. Notice I said "candle" as opposed to "bud", the distinction between a bud and a candle is important. The buds will set during the previous fall and may grow/swell through the winter and spring. Here I'm concerned with candle elongation, specifically the observable green growth above the node and the protrusion of needles through their protective paper-like covering. Repotting during candle elongation must be done with care...as opposed to repotting a tree at this stage, when the buds are just starting to show signs that elongation is eminent. I want to repot before I see elongation. Repotting this tree in April is "late", but not dangerous. It also indicates to me that their may not substantial root growth yet, which is what I want. If I were to pull off the pot and see many delicate, plump white roots I would risk unduly stressing tree if I worked the soil out with a rake or chopstick. I have done so, but with great care.

This a close up of a bud that has not elongated yet, but sap is starting to push up through the branch's vascular system to the buds that will become candles in about 2-3 weeks. Can you see the small resin droplets?

Here are some JBPs ages one, 2, 4, 5, 10+
The 1 & 2 year olds were bare rooted in March '17 so that the roots could be untangled and spread radially; young pines will tolerate bare rooting. The 4 year old pine was moved out of a colander into a pond basket in the 1st week of April. It had been in a 1:1:1 mix of lava pumice and akadama, so the fibrous root system had formed a healthy, dense root cake. The soil at the edge of the cake was worked out with a chop stick from the top, sides and bottom, removing about 1/2" soil from the top and sides. Only the circling and clumping roots on the bottom were loosened and trimmed, leaving the much of the root ball undisturbed. All other exposed root tips were trimmed, leaving about 1/8" of the tips exposed.

Above: a repotted 1 year old that was bare rooted, down ward growing roots trimmed back in favor of lateral roots; 2 year olds in 2" pots, bare rooted and put into colanders.

Below: 4 year old pulled out of 6" colander at end of March '17, repotted as described in previous post. I'm wetting the soil before inoculating root ball with mycorrhizae, this helps the powder stick to the root ball. I only inoculate trees with no visible mycorrhizal culture. In the 4th image you can see the beneficial white fungus.

Continued from above:
Note about the 33rd image in the set below - this is a red pine. the sacrifice branch was pulled up so that it is vertical. You don't want the tree to waste energy readjusting itself to vertical growth, while this may not harm a JBP it may slow down a JRP which aren't as vigorous.

aframe said:

Continued from above:
Note about the 33rd image in the set below - this is a red pine. the sacrifice branch was pulled up so that it is vertical. You don't want the tree to waste energy readjusting itself to vertical growth, while this may not harm a JBP it may slow down a JRP which aren't as vigorous.

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The branch you pulled up is the sacrifice and not the future trunk? I guess I would have assumed the growth out to the right was the sacrifice given you left is growing long and straight. I assumed the part you wired upward and put movement into was the future trunk line. (my thinking was the red is sacrifice and blue is trunk line)

Just wanted to say ---- Thank You.
Good Day
Anthony

sidesummy said:

The branch you pulled up is the sacrifice and not the future trunk? I guess I would have assumed the growth out to the right was the sacrifice given you left is growing long and straight. I assumed the part you wired upward and put movement into was the future trunk line. (my thinking was the red is sacrifice and blue is trunk line)

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Blue is next trunk section, red is the sacrifice; I pulled the sacrifice up with wire after I took this photo

Getting back to when these JBPs were repotted;
Here a couple 2 year olds from the same batch - they look similar but one began growing in February, the other in mid March. The one on the left started earlier, so the candles have elongated more relative to the tree on the right.

Here are the buds on the left and right trees, respectively.
The buds on the left tree have elongated, but more importantly the needles have begun to protrude.
The buds on the right tree have begun to elongate, but the tree isn't pushing out needles quite yet.
Ted Matson describes the following progression in stages of bud growth: buds, candles, the pineapple-phase and the porcupine-phase. He has said pines may be repotted through the pineapple phase, where the candle's texture resembles a pineapple. However I find that is generally too late in my area because the root growth is too active, and repotting at this stage may cause severe stress when half bare rooting or other significant root reduction techniques.

Continued from above:
the tree on the left was repotted in January, the one on the right in February.

Below:
These 2 trees were repotted last fall, 2016 - the one in the terra cotta pot in November, the one in the white pot was done in December. They started elongating and pushing needles a month earlier than the trees repotted in spring 2017. The take away is: positive results from fall repotting.

Here's a 4 yr pine that was repotted out of necessity on March 10th, 2017:
The roots grew through the drainage layer and out the hole in the bottom. This can cause problems later on, especially in a deep pot because the roots have mostly populated the bottom third of the pot. This makes it hard to achieve even moisture content. In the pics below, I'm pointing to dry soil, then a matted root mass, then new tender roots that have grown rapidly into the drainage where there is an abundance of oxygen, moisture and heat ( heat from the clay tile counter top on which it was sitting radiates well after dark)
Trying to keep the top half of this root ball moist would create an environment condusive to root rot at the bottom of the pot. I loosened the root ball with a chopstick and gently put it into a pond basket, working new soil into the root ball and spreading out older, lignified roots. Trying to manipulate the fleshy white roots will only cause them to break; I missed the window to work the roots on this tree so I'll have to do it next spring, as fall may be too early.

aframe said:

They started elongating and pushing needles a month earlier than the trees repotted in spring 2017. The take away is: positive results from fall repotting.

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Such heresy!

aframe said:

Trying to keep the top half of this root ball moist would create an environment condusive to root rot at the bottom of the pot.

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Why wouldn't this be analogous to air-pruning deep roots (i.e. deep root tips die and stimulate branching in the upper parts of them)?

BTW, I'm diggin' this thread.

0soyoung said:

Why wouldn't this be analogous to air-pruning deep roots (i.e. deep root tips die and stimulate branching in the upper parts of them)?

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The roots were clogging the drainage hole, keeping the moisture level greater at the bottom of the root ball and impeeding the drainage. Consequently I could not water often enough to bring adequate levels of oxygen and moisture to the upper part of the pot to encourage strong root growth in the upper half of the root ball.
Glad to hear you like the thread

aframe said:

Trying to keep the top half of this root ball moist would create an environment condusive to root rot at the bottom of the pot.

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Just a side question and assuming the pot drainage holes are not clogged up with roots. How do you guys feel about keeping the moss on the soil surface of a JBP?
I saw the Bonsai Mirai (Spring Fundamentals) video where Ryan placed copped sphagnum moss on the surface after removing the broken down fert layer in the pot however it wasn't a JBP he was doing it to.
I started taking the moss off mine but stopped after I came across some white feeder surface roots growing underneath it.

If you have a great birthday, @aframe have a bunch of beers the next day to celebrate!!!!

Drew- your comment Reminded me of a conversation between some of the members at my local bonsai club. During one of Ryan Neil's visits to our club he stated that he leaves the moss on all year. So some members followed this and in Oregeon this is all fine and dandy but in the hot valley where we live it's no bueno and that moss needs to be taken out.
Btw- Ryan Neil is awesome and during the demo's his technique's are clearly conveyed while engaging everyone to use their brains is pretty fuckin cool (for lack of a better word).

Back to the topic I am wondering if I missed the window of repotting could I still not work the roots if I had to plant a jbp deeper in a new pot that will allow me to plant it deeper. Reason being when I got home after my purchase of this jbp I noticed a little beneath the soil line there is some reverse taper. I think the way the wire was put to make the twisted look kind of causes this reverse taper at the base and just need to plant it deeper. Without messing with the roots I should be ok ? Hopefully

This is a great thread about repotting based on first hand experience. I am in the situation of looking at a likely fall repotting because I didn’t use quality soil on a field grown tree when first dug it out. May I ask the timing of your fall repotting and how much time did you give the trees to recover before the first frost?
Thank you.

Really helpful thread!

@just.wing.it Heres a thread that may help.

Hartinez said:

@just.wing.it Heres a thread that may help.

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Much appreciated, kind sir! Thank you!