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Enquiry about over-watering or under-watering a bonsai tree and trying to determine what the watering issues are.

We have received an email from James about his bonsai. It is obviously suffering from watering issues and I have been trying to help him determine the cause of the problem. I thought the following information may be of interest to other readers.

It is not always easy to determine if the bonsai is suffering from over or under watering issues.
In principle over-watering is a slow deterioration where the bonsai is over-watered for many weeks, the roots begin to rot and then become inefficient at taking up water , you then see symptoms which look similar to the bonsai drying out. (ie. Dry and crispy leaves).
Minor over-watering is often characterised but soft black tips of the leaves.
Another indication of over-watering is the trunk of the bonsai can becoming loose in the pot and it may wobble.

The symptoms of lack of water (under-watering) are rapid, the leaves wilt and go dry and crispy and drop off.
The subsequent bonsai care is different.
If you think your bonsai has been under-watered and allowed to become too dry please stand the bonsai in water so that the water covers the entire pot. Leave for 5 , 10minutes and then allow to drain.
This will evenly re-wet the soil. You can then check daily and keep the soil damp (not too wet). A bonsai without leaves requires less water.

If a bonsai has been over-watered it will take many weeks to see any improvement. The roots must re-grow before you see any signs of new shoots. It is important to keep the soil just damp and not wet. Please do not feed a bonsai until it shows signs of recovering.

I hope these tips help.
Sarah – Bonsai Direct

18 replies

  1. Hi,
    I juts bought what I believe to be a (musk maple) premna bonsai, Since it came with some live moss grown on the surface, I decided to remove it, at the same time I watered it. the next day I checked, I found maybe 5 leaves on the surface, they were slightly dried up, and they were slightly yellowish, day after that, more leaves started dropping. I only watered two days after I did. The soil feels slightlay dry, is it it a sign of under watering? I’m quite concern, at the moment it’s placed with indirect sunlight, Please help save my bonsai

    1. This is either a sign or under-watering or re-acclimatising. It is not a bonsai variety we grow so maybe worth seeking help from the nursery that you purchased it.

  2. My ficus microcarpa trunk remain soft under the wet soil my ficus has started dropping green leaves and the stem attached with leaves looks thin just like it has lack of water I had throughly watered until the water comes out of the drainage holes in plastic pot one week ago then I started shower when the soil becomes dry and now there is spring in pakistan.ficus is also growing new leaves but it is shedding old leaves.i keep my plant both indoor and outdoor.i have checked it’s trunk under the soil is soft it is general or the trunk is going to be not under the soil plz reply me I don’t want to lose my ficus.

    1. Dear Anmol,
      This could be seasonal leaf drop if you are entering summer – the old leaves can drop (but not the new leaves).
      If you are worried it maybe worth emailing the nursery where you purchased the bonsai tree with a photo so they can check for you.
      Please keep the soil damp at all times (but not too wet). I hope this helps
      kind regards

  3. Hi I just purchased a maple bonsai a week ago and it has gone from nice green leaves to dark green/brown dry crisp leaves I have been watering it heaps since i notices the change. But now the leaves are starting to fall off and the stem of the leaves wilted also some of the ends of the branches had wintered and gone brown. The soil is wet. And it only get a small about of direct sun light in the morning. Any ideas what’s wrong or if iv over watered it. Before it was bad I had it in part sun part shade. We had a storm at on stage but I took him out of direct wind or rain and that’s when he went funny.

    1. Dear Alana,
      This could be leaf scorch from the wind.
      I do not know where you are in the world but this can cause crispy leaves.
      Please keep the soil damp and not wet.
      I would suggest you send a photo to the bonsai nursery you purchased the bonsai from just to double check.
      Kind regards Sarah

  4. My ficus bonsai is 7 years old….
    A month before I saw some roots are coming upward from the soil and 2-4 yellow leaves…. I thought that was normal…
    But after that 10-20 leaves turned yellow…
    I am very tensed what should I do
    Why this is happening to my plant

    1. Hi Riya,
      If it is the older leaves which are dropping (and not the new growing tips) then it is likely to be seasonal leaf drop.
      Kind regards

  5. Hey, my Bonsai that I recently adopted from my grandmother, which she purchased at walmart, is growing great on one side, but all the leaves have fallen off the other… Is there something I’m missing? I believe I’m overwatering a bit as well since some of my leaves turned yellow beforehand but never really shrivelled… Have any suggestions..?

    1. It maybe that the bonsai needs turning regularly to get even daylight on both sides. It is very difficult to advise as I cannot see the bonsai.
      I am sorry i cannot be of more help
      kind regards Sarah – Bonsai Direct

  6. Hi, I have a Chinese Elm Bonsai, I’ve had it for about a year now, the leaves have started to go yellow and crisp. I thought it might have been from root rot so I took it out the pot, cut off the dead roots and re potted it into the same pot. But it still seems to be yellowing new leaves and dropping them. Could this be due to overwatering?

    1. Hi Jonny,
      Do you feed your bonsai with bonsai feed? Yellowing is often a sign of lack of nutrients or of seasonal change.
      If it is just the old leaves and not the new growing tips it will just be lack of sun at the moment.
      I hope this helps
      best wishes

  7. Hi Sarah,

    I have a 8-year-old rheingold arborvitae bonsai. The seller told me to water it every second day and after 10 days the leaves near the trunk or the leaves near the beginning of a stem are becoming brown/blackish and sometimes crispy. The thing is the the leaves on the top of the tree or on the higher parts are very healthy but as you go down you see they get more unhealthy. Is it because of over-watering? if so what should I do now? Thanks a lot.

    1. Hi Mohammad,
      Without seeing the tree I cannot be sure.
      Blacks tips is usually a sign of overwatering but crispy leaves is usually a sign of under-watering.
      Maybe if you brought it recently ask the seller his opinion.
      Kind regards Sarah

  8. I’ve had my Chinese Elm for about 2 years now and in the past few months it started to drop leaves, grow new ones, drop them, grow new ones, for about 4 months straight. But now.. only a few leaves left. No sign of new leaves for the past 2 months. I water it weekly by putting it under water for 5 minutes, as I was instructed upon buying the bonsai. I also spray the bonsai every week with water. Any idea what could be the problem?
    Kind regards,

    1. Hi Anna,
      Do you feed the bonsai at all? Also when the leaves drop have they gone dry and crispy? I suspect submerging the bonsai once a week at this time of year is not enough.
      We are currently watering daily so I think you have been given the wrong information.
      If you are worried please send some photos.
      Many thanks

  9. I’ve had my bonsai for around 3-4 weeks it’s 7 years old and a Chinese elm , I’ve got it on the kitchen window sill , over the last week some leaves have turned yellow and dropped off and some have curled , but there soft wen you touch them , some also got black on the leaves and tree is just a tiny bit loose but not that much , what do you think the problem is ,

    1. Hi James,
      This is caused by lack of water. Please soak as per my email.
      Many thanks

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