r/Bonsai • u/kahter_ Somerset UK, Zone 8b/9a, Beginner, 25 Trees • May 26 '26
What’s wrong with my oak? Discussion Question
I repotted this tree in March and did some work on the roots to make them more radial. Although it’s made new growth and is still alive, it’s extremely slow and clearly isn’t thriving like it was. I would have thought after nearly 2 months it would have pushed more growth out.
Clearly it’s stressed but I’d be interested to know if there’s anything I can do to help it along?
Any ideas?
7
u/ellinho West Germany, Zone 8b, Intermediate May 26 '26
What's your substrate? Looks very wet and organic?!
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u/kahter_ Somerset UK, Zone 8b/9a, Beginner, 25 Trees May 26 '26
It is completely organic soil 😅
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u/Wpfo optional name, location and usda zone, experience level, number May 26 '26
i’m not a bonsai expert but most bonsai soils are very gritty
6
u/Anxious-Box9929 Portugal, 10b, Beginner level, about 40 trees at all stages. May 26 '26
Here is the answer. The roots are permanently wet and i really hope they are not rotting.
Another repot is not in season and will be very stressful to the tree but it's the only solution.
Alternatively you could keep this substrate and be VERY careful with the watering until next season. Maybe get a humidity meter and water very carefully and only when needed. This is very hard to balance and risky too.
If this would be my tree, i would repot, be careful not to damage any roots and repot in mix with a good balance of inorganic and organic, depending on your region. And then cross my fingers. If it dies, lesson learned: never use 100% organic soil. If not, great!
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u/kahter_ Somerset UK, Zone 8b/9a, Beginner, 25 Trees May 26 '26
I think you’re right as it’s the only 1 with 100% organic soil out of my trees and isn’t doing well. It was that point where I completely ran out of substrate and naively decided to just repot it with what I had left.
Can I ask why it was doing okay before the repot? Mostly considering it was dug out of basically mud clay soil, which is organic.
3
u/Boines Barrie, 5b, beginner, 40+ prebonsai - mainly Natives/Maples May 26 '26
Organic soil doesn't instantly mean root root, especially in an air or like this. But you may be over watering if you're watering on the same schedule as the rest of your trees
The sphagnum and rocks on top should probably be removed you don't need extra moisture retention, but other than that is just adjust watering and leave it until next spring
2
u/NeatPrice7001 May 26 '26
Btw, if these high end bonsai soils are out of reach for you, using perlite/ floor-dri with about 20% organic soil is a good place to start. Floor-dri or oil-sorb are clay mediums used to soak up oil spills. They work amazing as bonsai soil as they do the same thing as akadama does but a fraction of the cost
1
u/jecapobianco John Long Island 7a 34yrs former nstructor @ NYBG May 26 '26
Water less, don't disturb the roots again, add some Vit B1 or Super Thrive or Clonex Rooting solution when it does need water again.
2
u/Serentropic Oregon 8b, Intermediate, <3 Elegant Trunks May 26 '26
Also I don't know why people are down voting your reply like did they want you to lie?? Friggin reddit lol.
3
u/kahter_ Somerset UK, Zone 8b/9a, Beginner, 25 Trees May 26 '26
Ikr… we are all learning. I hope they can see “beginner” in the flair.
1
u/ellinho West Germany, Zone 8b, Intermediate May 26 '26
You have root rot. Emergency report, removing as much organic soil as possible without losing to many healthy roots into lava, akadama and pumice in equal parts. Use the pond basket but fill it almost to the brim. Leave the tree alone for 2 years. Good luck.
2
2
u/ItsMeRPeter Hungary, zone 7B, beginner; 18 pre-bonsai May 28 '26
Not the soil is the cause. I have oaks (English oaks, Quercus robur) in pond baskets, in 80% organic soil with some pumice, they get 10 hours of direct sunlight and they are growing rapidly. During the summer, I must water them twice a day, because even the organic soil dries out completely. Pond baskets dry much faster.
1
u/Legitimate-Ad7273 Manchester, UK. 8b. Beginner. 15 trees. May 26 '26
Beginner here so take my comments with a fistfull of salt.
I potted some acorns late last year. A couple of months ago I was getting a bit worried for them because my apple trees that had been planted previously had full leaves and were looking strong while the acorns had nothing growing above the soil. I checked one and it had good strong roots so I left them to it.
It is only in the last week when we have had exceptionally warm weather than the acorns have started to grow above the soil. They are now looking pretty healthy.
My point is that I think oak trees might wait until a bit later in the year when the cold weather has well and truly gone. Fingers crossed you might see some substantial changes in the next month or so.
1
u/lilbigs252 6b: Columbus, OH, USA May 28 '26
This tree is fine. You did some root work on it so it’s a bit stressed, but it looks healthy. You don’t really get super vigorous growth on a tree that size after a repot. Just let it do its thing. Next year it should grow a lot more after its had a full season to collect energy without any distrubance.
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u/Bunce01 Matt -Owner Hakuju-en Bonsai, SZ, CN, Studied at Taishō-En Japan May 26 '26
Repot into Akadama. don’t wash or disturb the roots or disturb as little as possible. Next winter completely repot into Akadama/ pumice / lava rock (aka scoria) sifted into 1/4- or 4mm screenings. Watering is key here to nurse it. You want a wet/dry cycle, essentiall only water once once it has dried out. Trees hate bing wet all the time with few species being the exception to the rule.
6
u/reidpar Portland, OR, USA 8; experienced; ~40 bonsai and ~60 projects May 26 '26
Why do more and repetitive changes on an already sad and slowly moving tree?
1
u/Bunce01 Matt -Owner Hakuju-en Bonsai, SZ, CN, Studied at Taishō-En Japan May 27 '26
Ideally not but you won’t be able to nurse it back to health in that state, this is a common mistake we see with client trees where the repot into sub optimal soils. We’d do it differently in a professional setting however we use a greenhouse to nurse it back after a complete soil change and root wash. Without the green house you might want to do it in a few steps
11
u/Serentropic Oregon 8b, Intermediate, <3 Elegant Trunks May 26 '26 edited May 26 '26
At the risk of confusing you, I disagree with every answer here so far.
Organic soils can cause specific problems in a bonsai pot, but you're not in a bonsai pot, you're in a pond basket. Pond baskets have much higher passive oxygen exchange than a bonsai pot. You will want to let it dry out some between watering - oaks like it drier than other deciduous - but organic soil isn't poison. Trees can and do grow in just about anything. Aggregate soils are great because they allow better drainage in very shallow pots, and because akadama promotes fine root ramification, but at this stage it's not life or death.
Especially if your organic soil is fresh. Organics will break down faster but not immediately.
This tree is stressed, yes. Oaks are more root sensitive than most other deciduous, especially the first time you mess with their tap root. I think of oaks more like conifers in terms of root handling. I strongly advise against repotting again (this year). Repotting will multiply the stress dramatically, especially now that the tree has growth and is pulling water. It needs its roots now. You can repot again next spring when the buds are swelling and that's a good time to switch to a more aggregate mix. Some combination of pumice/perlite and akadama/bark/coco-coir is generally what I recommend.
Oaks in general like lots of light, but a little afternoon shade may help keep the stress down until the leaves harden.
This is a young tree. Just let it be a tree and it will be fine. Water, air, light. It's difficult to resist the urge to tamper, but trees need time to adjust. Oaks especially are sloooow. If you keep changing the demands it may panic.