Recently repotted JBP has browning needles

[Bonsai Nut]

I think the only thing you can do at this point is to wait and see what happens.

This is the best advice. Pines have an annual rhythm where you do work in certain windows of time based on season and where you live. You have to be very careful not to overwork them. If you repot, particularly if you trim roots, you should not do any work to the top of the tree until it has recovered from being repotted, and that normally means to wait a season before you pull needles or prune or cut candles.

Fortunately Japanese black pines are very strong trees. It may recover. But don't do anything else to it this year.

 

[Wulfskaar]

I like to check the What did you do today? thread often. You can see what people are doing at any point in the year. It's interesting to follow and it can be a helpful guide.

 

[The Barber]

Did you bare root it? That could also cause issues.

 

[Bonsaidoodle]

Recently (3/24/25) I removed my 2 1/2 year old black pine from its pot to trim roots. I replanted in same pot with fresh soil. About 2-3 days after repotting, I pulled a good amount of needles and trimmed remaining ones. Some of the top needles on the most mature growth started to brown and now tips of needles I trimmed are beginning to brown as well.

Just wanted to get some thoughts and suggestions from you all. Am I doing anything wrong?
Any advice or comments are greatly appreciated
Thanks!

(4/8/25) 15 days after repot

There has been ton of rain lately. I put a block under one side, keeping it elevated and tilting the pot to ensure good drainage. Haven’t noticed any further browning

Continuing to be optimistic

 

[Bonsaidoodle]

This is the best advice. Pines have an annual rhythm where you do work in certain windows of time based on season and where you live. You have to be very careful not to overwork them. If you repot, particularly if you trim roots, you should not do any work to the top of the tree until it has recovered from being repotted, and that normally means to wait a season before you pull needles or prune or cut candles.

Fortunately Japanese black pines are very strong trees. It may recover. But don't do anything else to it this year.

If JBP has no more visible signs of decline, what should I do during growing season? Do I fertilize or just leave it alone to grow naturally?

 

[bwaynef]

I'd wait until you see signs of improvement, rather than a lack of continued decline, to start fertilizing. Begin slowly and give the tree time to respond. Let the tree lead this dance. If its color improves, or you see more vigor, or budding, give it a bit more fertilizer and watch it.

 

[Desert O'Piñon]

I put a block under one side, keeping it elevated and tilting the pot to ensure good drainage.

Since I really don't know anything about pines (yet), I won't comment on pine care. But I do know that conifers in general really dislike wet/damp roots. I would dare say that most (not all) bonsai pots have drainage holes in the center, so it's possible that tilting it may actually cause the pot to hold more water, not less. Also, if you have a covered area, you might consider keeping it there during rainy spells. After repotting any tree, it's a good idea to limit intense sun exposure and gradually reintroduce it to more sun until it's in full sun, full time. Connecticut is polar opposite of the desert, so it's not quite as urgent there, with your cooler weather and higher humidity.

Welcome to the forum! Your thread has already taught me a few things.

 

[WIlliam_Butler_Yeets]

If JBP has no more visible signs of decline, what should I do during growing season? Do I fertilize or just leave it alone to grow naturally?

Yes, I'd say leave it alone, start fertilizing once it shows signs of regaining strength, if you have other trees, pay attention to them, or if you don't, maybe get a few more. The surest way to kill a tree seems to be smothering it with attention, you always notice something that needs to be done or this that or the other. You can avoid that by having a few more so when you want to mess with a tree you aren't doing the same one or two all the time.

 

[bwaynef]

After repotting any tree, it's a good idea to limit intense sun exposure and gradually reintroduce it to more sun until it's in full sun, full time.

Do with it what you will, but Boon teaches to put the tree back into conditions it was in prior to repotting. If it was in full sun prior to repotting, put it back into full-sun. The additional heat will be beneficial in the regeneration of roots. That's likely caveated with the understanding that the repot happens at the right time of year.

 

[Desert O'Piñon]

Do with it what you will, but Boon teaches to put the tree back into conditions it was in prior to repotting

Thank you, good to know. It's veterans like you that newbies like me need, so we can be corrected before we make the mistake(s).
@Bonsaidoodle , listen to @bwaynef, he knows far more than I do.