When to re pot JBP?

[BonsaiButler]

Just picked up these two black pines that appear to be quite root bound, just wondering when/how Japanese black pine is repotted. I want to put them into pond baskets with pumice. How should I go about doing this?

 

[justBonsai]

You probably should wait until next spring when the candles begin extending. Its a bit late and risky to do repotting right now. Someone else could probably give you more detailed advice. I did a mid summer repotting on a white pine once and the tree definitely suffered a bit. In repotting properly the successive spring, the tree didn't skip a beat.

 

[aml1014]

I'll be reporting one of my teachers jbp next week, and I'm in the high desert. Makes me pretty nervous but she doesn't seem to think it'll mind (she's only been doing bonsai for 45 years lol)

I repot mine in early spring, just to be safe.

Aaron

 

[Giga]

You could always "fuzz up the rootball" and plant in a colander full of a pumice mix

 

[Paradox]

Looking at those pictures. It is way too late to repot now.

You repot JBP in early spring when the buds begun to swell and before they transform into candles.

 

[Dav4]

There are those who re-pot JBP mid summer...I'm not one of them.

 

[coh]

If those are completely root-bound, I might go ahead and slip pot them into a slightly larger pot right now (just tease out the edges of the root mass slightly and use a similar potting mix), then do a full repot (probably half bare-root technique) in the spring. But, if they seem healthy and are draining well, the safest thing would be to just leave them until next spring.

 

[LanceMac10]

leave 'em 'till next spring.
explain "appear" in a little more depth. Did you tip 'em out to take a look?

 

[namnhi]

I don't think they have any issue with waiting until next spring...

 

[jeanluc83]

I would wait until next spring. Root bound is not necessarily a major concern. It only becomes a concern when drainage is reduced. Even then you just need to be more careful about your watering. It would be more dangerous to repot out of season than just let them be for another year.

 

[0soyoung]

This is a subject for which our gone but not forgotten JKL used to say

I suppose you can repot just about anytime, if you know what you are doing.

 

[BonsaiButler]

Thanks for all the help everyone.

@LanceMac10
I tried to pull them up to have a peek at the root ball, couldn't get either one to budge.
I'm gonna have to cut them out of their pots next spring.

 

[Potawatomi13]

Thanks for all the help everyone.

@LanceMac10
I tried to pull them up to have a peek at the root ball, couldn't get either one to budge.
I'm gonna have to cut them out of their pots next spring.

Have one came from similar kind of pot completely root bound and had to cut off pot. Did this last year and was no shaking out roots or removing soil. Solid mass of roots. So cut off bottom 50% tried to get top surface down to roots and failed, put in much wider shallower pot with good mix. Has grown well except one branch was little slow at first. Expect will just have to wait for dead roots to rot away in time and develop good root mass as time goes on. Really amazing tree survived brutal potting and such bad roots. Strongly suspect doing this any time but early spring would be bad idea.
Where is your home?

 

[BonsaiButler]

Thats why im nervous about what im gonna find when i try to repot.
I live in roseburg oregon.

 

[0soyoung]

Assuming you didn't decandle, you can repot just about anytime from August to November. Repot means cutting off about the bottom third of the pot plug of roots and dirt and then washing out no more than one half of what remains. If you choose to do this in Aug/Sep you likely can wash out the other half next spring - judge by the apparent vitality next spring (if weak, wait until Aug/Sep again). You will need to be very careful about making sure the old part stays properly moist (water can roll right off it and thru the new substrate on the other half).

 

[Adair M]

Assuming you didn't decandle, you can repot just about anytime from August to November. Repot means cutting off about the bottom third of the pot plug of roots and dirt and then washing out no more than one half of what remains. If you choose to do this in Aug/Sep you likely can wash out the other half next spring - judge by the apparent vitality next spring (if weak, wait until Aug/Sep again). You will need to be very careful about making sure the old part stays properly moist (water can roll right off it and thru the new substrate on the other half).

Oso, you live in the Pacific Northwest as does the OP.

Maybe fall repotting works well for your region. I only repot pines in late winter/early spring.

Except Mugo. I don't have any. Vance says to repot Mugo in the summer.

 

[Leo in N E Illinois]

JBP - your local climate is critical in deciding when to do anything. Second - JKL - Jim Lewis was right, if you know what you are doing, you can repot anytime. - thanks Osoyoung. Osoyoung is in your same general climate region, listen to his advice, but he is a couple hundred miles north of you, so you will still have to think about the climate differences between where he is at and your place. You are west of the Cascades, inland from the Pacific. Once of the mildest climates in North America. You could probably get away with repotting at times when the rest of us would be certain that disturbing the roots would be "instant death".

I started dabbling with bonsai some 45 years ago. I did not "get serious" about bonsai until about 15 years ago when I started taking classes with various teachers, self taught before then. I have always had at least a few trees in pots for the last 45 years. I bought my first JBP back in 1981. I have probably killed over 100 of them since then. The longest I kept one alive was 18 years. Right now I have one that I have had at least 7 maybe 10 years. Currently I have 7 younger JBP plus the one that is a little older. I am at the north limit of where JBP are hardy, I must protect them in winter or I will loose them, maybe not every winter, but within 5 years one winter will kill them. Because I protect them in winter, I found repotting in late summer, when temperature begin dropping below 65 F at night is a relatively safe time to repot. About equally successful as spring repotting. My spring repotting has been less than 100% successful. I lost several JBP due to being repotted too early in Spring. Late summer repotting, I also have lost JBP due to being repotted in late summer. My success rate is finally up to about 85%, not 100% for either time of year.. I live within 2 miles of Lake Michigan, with little in the way of "city" between me and the lake. I get a fairly strong "Lake Effect" in spring. Growers just 3 miles west of me, away from the Lake, have a very different experience with JBP. I am in a unique micro climate and it has taken me years to adjust to it. Actually, for Chicago natives, if you are west of Green Bay Road, or Ridge, on the "north side", you are out of the main "Lake Effect". There is a natural ridge, that marks the lake basin, that these roads follow. In the basin, air cooled by the lake dominates (or warmed by the lake in autumn & winter).

Spring repotting - repot before the tree has started to wake up is fatal. My spring tends to be cool, too cool to wake up JBP very quickly. To successfully repot in spring the buds need to have at least doubled in size, and have started to elongate into candles. Any sooner than that time, and if we get a cold week, the tree will stall out, buds will die and tree will collapse. Look at your weather, don't repot until you can reliably predict that you will get at least 5 or more days a week with highs above 60 F hopefully with a few days warmer into the 70's. JBP is a "lowland" pine, loves heat, and is torpid, nearly dormant anytime temps are below 45F. They need warmth to wake up, don't repot before you are sure it will stay warml This year we had a warm April, with many 70 F and even an 80 F. then followed by a full 30 days of May where the highs never got above 60 F. We stayed above freezing, barely, possibly with a few patches of frost, but it never warmed up. Many of my JBP still have very young candles today. They really didn't start to move until the last week, beginning of June. Since we can get our first frost the beginning of October, our last date for decandling is about June 15. Many of my JBP won't get decandled this year, it is just too cold, they got growing too late.

The above is just to point out how you absolutely have to look at your local micro-climate, and adjust your calendar of JBP care techniques. Don't follow my suggestions for timing, but do follow your observations of what your trees do and when they do it in your climate. Take notes when candles begin to elongate. Note when you get your first and last frosts. Make your own calendar of JBP care. It will not be the same as anyone else's. Osoyoung is likely to have a calendar that is more similar to yours than anyone else on the forum, but there will be differences.

Summer repotting, you really need to be late enough that the intense 95+ F weather is done for the year. Also if you get an episode of warm but very low humidity weather in early autumn, you must move the tree to the shade and keep it well watered. You need to stay on top of your aftercare.

Taking off too many roots can be fatal,. If you have a large plug of old, hard to wet soil you need to water by immersing the pot in a bucket or large pan of water. Leave it soak for 10 to 20 minutes, but don't forget about it. Leaving it longer than a couple hours can create its own problems. (invites rots of various types). Easier to do with shohin, difficult if you have large trees. Large trees you might have to water several times in the hour or so that you spend with the rest of the collection. Water it, come back 5 minutes later and water it again, do it at least 3 times. That will help to wet a plug of old media.

In a marginal climate - only one major disturbance per year, the tree needs to recover after each major operation. Wiring, carving, repotting, all are major disturbances. Do too much without allowing recovery time will slowly kill the trees. You nee to be very conscious of the health of your tree, and only do the "next thing" if the tree is showing vigorous growth.

Last, there is no such thing as a "gentle slip potting". No mater how careful you think you are, you disturb the tree, and "slip potting" should count as a major operation on the tree.

 

[petegreg]

Fantastic coverage of the topic. Thanx.

@Vance Wood , this is maybe the only one I miss dealing with mugos. How many (major) insults? Are they so excusing?

 

[girv]

JBP - your local climate is critical in deciding when to do anything. Second - JKL - Jim Lewis was right, if you know what you are doing, you can repot anytime. - thanks Osoyoung. Osoyoung is in your same general climate region, listen to his advice, but he is a couple hundred miles north of you, so you will still have to think about the climate differences between where he is at and your place. You are west of the Cascades, inland from the Pacific. Once of the mildest climates in North America. You could probably get away with repotting at times when the rest of us would be certain that disturbing the roots would be "instant death".

I started dabbling with bonsai some 45 years ago. I did not "get serious" about bonsai until about 15 years ago when I started taking classes with various teachers, self taught before then. I have always had at least a few trees in pots for the last 45 years. I bought my first JBP back in 1981. I have probably killed over 100 of them since then. The longest I kept one alive was 18 years. Right now I have one that I have had at least 7 maybe 10 years. Currently I have 7 younger JBP plus the one that is a little older. I am at the north limit of where JBP are hardy, I must protect them in winter or I will loose them, maybe not every winter, but within 5 years one winter will kill them. Because I protect them in winter, I found repotting in late summer, when temperature begin dropping below 65 F at night is a relatively safe time to repot. About equally successful as spring repotting. My spring repotting has been less than 100% successful. I lost several JBP due to being repotted too early in Spring. Late summer repotting, I also have lost JBP due to being repotted in late summer. My success rate is finally up to about 85%, not 100% for either time of year.. I live within 2 miles of Lake Michigan, with little in the way of "city" between me and the lake. I get a fairly strong "Lake Effect" in spring. Growers just 3 miles west of me, away from the Lake, have a very different experience with JBP. I am in a unique micro climate and it has taken me years to adjust to it. Actually, for Chicago natives, if you are west of Green Bay Road, or Ridge, on the "north side", you are out of the main "Lake Effect". There is a natural ridge, that marks the lake basin, that these roads follow. In the basin, air cooled by the lake dominates (or warmed by the lake in autumn & winter).

Spring repotting - repot before the tree has started to wake up is fatal. My spring tends to be cool, too cool to wake up JBP very quickly. To successfully repot in spring the buds need to have at least doubled in size, and have started to elongate into candles. Any sooner than that time, and if we get a cold week, the tree will stall out, buds will die and tree will collapse. Look at your weather, don't repot until you can reliably predict that you will get at least 5 or more days a week with highs above 60 F hopefully with a few days warmer into the 70's. JBP is a "lowland" pine, loves heat, and is torpid, nearly dormant anytime temps are below 45F. They need warmth to wake up, don't repot before you are sure it will stay warml This year we had a warm April, with many 70 F and even an 80 F. then followed by a full 30 days of May where the highs never got above 60 F. We stayed above freezing, barely, possibly with a few patches of frost, but it never warmed up. Many of my JBP still have very young candles today. They really didn't start to move until the last week, beginning of June. Since we can get our first frost the beginning of October, our last date for decandling is about June 15. Many of my JBP won't get decandled this year, it is just too cold, they got growing too late.

The above is just to point out how you absolutely have to look at your local micro-climate, and adjust your calendar of JBP care techniques. Don't follow my suggestions for timing, but do follow your observations of what your trees do and when they do it in your climate. Take notes when candles begin to elongate. Note when you get your first and last frosts. Make your own calendar of JBP care. It will not be the same as anyone else's. Osoyoung is likely to have a calendar that is more similar to yours than anyone else on the forum, but there will be differences.

Summer repotting, you really need to be late enough that the intense 95+ F weather is done for the year. Also if you get an episode of warm but very low humidity weather in early autumn, you must move the tree to the shade and keep it well watered. You need to stay on top of your aftercare.

Taking off too many roots can be fatal,. If you have a large plug of old, hard to wet soil you need to water by immersing the pot in a bucket or large pan of water. Leave it soak for 10 to 20 minutes, but don't forget about it. Leaving it longer than a couple hours can create its own problems. (invites rots of various types). Easier to do with shohin, difficult if you have large trees. Large trees you might have to water several times in the hour or so that you spend with the rest of the collection. Water it, come back 5 minutes later and water it again, do it at least 3 times. That will help to wet a plug of old media.

In a marginal climate - only one major disturbance per year, the tree needs to recover after each major operation. Wiring, carving, repotting, all are major disturbances. Do too much without allowing recovery time will slowly kill the trees. You nee to be very conscious of the health of your tree, and only do the "next thing" if the tree is showing vigorous growth.

Last, there is no such thing as a "gentle slip potting". No mater how careful you think you are, you disturb the tree, and "slip potting" should count as a major operation on the tree.

Hey Leo or anyone else who can provide guidance here - Saw this post and just realized I repotted my JBP today and way too early. It is averaging 35-55 degrees over the next two weeks (Massachusetts) and I had to remove significant amount of roots as it my tree was completely pot bound. Sounds like the damage may already be done, but anything I can do to improve my chances till the weather warms up here? Keeping it protected in my basement or garage where it is slightly warmer? I had it in my bulkhead all winter and just took out last week.

 

[Dav4]

Hey Leo or anyone else who can provide guidance here - Saw this post and just realized I repotted my JBP today and way too early. It is averaging 35-55 degrees over the next two weeks (Massachusetts) and I had to remove significant amount of roots as it my tree was completely pot bound. Sounds like the damage may already be done, but anything I can do to improve my chances till the weather warms up here? Keeping it protected in my basement or garage where it is slightly warmer? I had it in my bulkhead all winter and just took out last week.

Full sun during the day, protect from freezes at night, keep the soil moist but not sodden- hopefully the tree is solidly wired in the pot so all the moving around won't hinder new root growth. I practiced bonsai for a decade in N. Attleborough for a decade. My first decent JBP was accidentally left out on the stand a day or two after it's first re-pot where I removed 70+ percent of it's roots. The temps fell to 26F, the soil was frozen solid the next morning, and I thought it was toast, but it didn't skip a beat. Here's a thread I have on it here... https://www.bonsainut.com/threads/japanese-black-pine-slant-style.6842/