Jan 4 2016

Improving the success rate of Yamadori

I have been using this technique now for over ten years and I have finally decided to share what I have learned. The technique is known as ‘sweating’ and is used extensively in arboretorial circles. I use for the following species: Cratageus, Prunus, and most of the Rosaceae family, do not use on evergreen species.

I collect trees with as much root as possible, but I have put roots on trees that have not had any.

Follow this procedure and your success rate in establishing your freshly collected yamadori will improve immeasurably.

  1. Collect as much root as possible
  2. Clear as much mountain soil but do not wash the roots
  3. Use the soil mix as shown below
  4. Clean cut the major roots as close to the trunk without spoiling the nebari
  5. Place the tree in the smallest container possible
  6. Ensure that the tree is well packed in the container
  7. Wire the tree securely in the pot
  8. Make sure that the cut branches are clean and NOT SEALED
  9. Saturate the soil
  10. Pile fresh sphagnum moss on the surface of the container
  11. Wrap the whole tree in a VERY large black plastic bag
  12. Place in a sunny position as the tree MUST GET HOT
  13. Humidity in the bag must be high at all times, mist spray daily
  14. After two or three weeks new buds will appear particularly around the cuts
  15. Ensure that they do not touch the sides of the bag.
  16. When the new shoots reach 5cm or 2” remove from the bag and protect from cold and wind, mist spray daily and keep out of direct sunlight.
  17. Keep watch for the new shoots hardening off, then you can feed with a very diluted solution; do not work the tree for the first 12 months.

Good luck, please do not copy these photos or the text, and share the link freely.

75 comments on “Improving the success rate of Yamadori”

  2. Hey that sounds really promising and I will try it.
    One question, how important is brightness? The fact that it shall be black bags is somehow strange for me

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  3. Hi Tony, I’m Vincenzo and I’m writing to you from Italy, thank you for sharing this very interesting technique … I wanted to ask you in what period can a beech and a hawthorn be harvested? should the transparent bag be placed after the black bag? after how long can fertilizer be applied?

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  4. Hi Tony,
    Shay from Israel (:
    Long time no see…
    I wanted to ask, is there a known biological reason for this behavior of the tree in dark hot and humid environment?
    Hope to see you soon!
    Thanks 😊
    Shay

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  5. Thanks for sharing this technique. I am a bit confused about how hot is “too hot” inside the black bag? Is 23 – 25 degrees Celsius too hot for trees inside the bags?

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  10. Hi Tony,

    My before message:

    ” I have lots of question. Sorry i’m french, i speak bad english.
    I want to do a yamadori of Ulmus campestris
    – Can I do the yamadori for the month of March or april with black plastic bag? If yes, then I put the black bag in full sun outside, half shade, shade or in a cellar?
    – Can i use this technical on ulmus?
    – The ulmus that I want to take is in a stone wall, Can this technique work for an elm without rootlets?
    Thank you man.”

    I used your technical for two Ulmus this year and it’s 100% successfull.

    But your technique has failed for a big oak and a maple of montpellier =( . When the new shoots reached 5cm, i remove from the bag and protect from cold and wind, mist spray daily and keep out of direct sunlight. But 2 mouth later the leaves of oak and maple have dried… When i scraped the bark, there wasn’t green, i remove trees from the pot and no roots have pushed…

    Why do you think my tests are unsuccessfull ?

    Should I put my trees in a transparent bag or a greenhouse after the black bag?

    Thanks Tony 🙂

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  12. Hi Tony,

    Thanx for writing about this great technique, I am using it second year now and it is working prefectly, I manage to put roots on a rootless yamadori hawthorn with trunk girth of about 15cm. Helped on many more trees too I believe and I put every yamadori in a bag since then. I am praising it everywhere I go with a reference to you and this article.
    Only negative thing I noticed so far is mold buildig up on some trees, but it looks like it doesn´t come back after I brush it off with a toothbrush.
    One question – at the moment I have a garden yamadori japanese maple collected a month ago, trunk diameter about 18cm – it is producing quite strong odour in the bag – is is ok to use this technique for it too? I am also worried about maple´s liability to catch various fungal diseases….which coul be aided by this wet environment…do my worries make sense?

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      • Thanx for the responses Tony.
        We have got few cold days in the last 2 weeks so thats why probably there was mold , bags didn´t get warm enough.
        Today it ´s just 3°C again so I expect it to build up again.
        As long as it don´t hurt the trees I don´t mind brushing it off.
        Anyways, it´s like christmas for me everytime I open the bags and see buds appearíng all over the trunks on more and more trees now after a month in bags, even on a big ones with some 20cm diameter trunks that my local bonsaists would be preparing tree years for collection 🙂 Very handy technique.
        All the best from your slovakian follower 🙂

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  14. Hi Tony,
    I have lots of question. Sorry i’m french, i speak bad english.
    I want to do a yamadori of Ulmus campestris

    – Can I do the yamadori for the month of March or april with black plastic bag? If yes, then I put the black bag in full sun outside, half shade, shade or in a cellar?

    – Can i use this technical on ulmus?

    – The ulmus that I want to take is in a stone wall, Can this technique work for an elm without rootlets?

    Thank you man.

    Lucas

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  15. hello Tony,
    I’ve collected a Hawthorn and treated the way you advised: in a big black plastic bag, spraying daily. I’ve placed it in the livingroom, in front of the heater. Now, a month after digging, the tree has new shoots, lenght between 1 and 8 cm.
    So now i think its time for point 16: When the new shoots reach 5cm or 2” remove from the bag and protect from cold and wind, mist spray daily and keep out of direct sunlight…. proctection from cold, does that mean: keep it frostfree, but place outside? Or what is the best i can do now? I think this is a tricky moment…
    Many thanks!

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  16. Great tips! My trick is vitamin B-1. It reduces transplant shock which is generally about 2 weeks, but can be even less with B-1. I’ve seen new growth in a little over a week. We don’t typically have to worry about humidity domes where I live in Oregon.

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  17. Hi, great work Tony, I have a collected semi cascade Blackthorn, have a few questions… does the bag need to be air tight or should there be holes pricked in the bag?
    I’m considering bagging the bottom half of my tree to gain some sacrifice branches and nebari…
    Justin

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  18. Hi Tony
    i dig up an old sea-buckthorn with deadwood and a hollow tree in february, and placed it in a container as you decribed here above. The three had hardly no roots. I places the tree inside the house with good light, in a big plastic box i made for the three. Every day i spray the tree, so the enviroment is always damp. within two weeks buds began to sprout. Now the the shoots are around 5 cm. Last week i remove the box, but the three was not happy with it: The leaves began to dry out. So now the plastic box is over it again. I give the tree superthrive for several times.
    What is the best i can do now? Hope that you can give me some tips to give the tree alive and kickin

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    • It’s all about heat and humidity… If the shoots are strong put the whole tree in a clear plastic bag. Make sure the new shoots do not touch the sides of the bag… Make a wire frame and put the bag over that… Seal the bottom… Spray regularly

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  19. Hi Tony,
    Can I use this method of sweating on an old Azalea I collected from the garden of a house Demolition?
    Also…is it a good idea to remove all the field soil and replace it with a pumice and sea soil mix or to leave some of the field soil close to the trunk and remove the rest in the second transplanting?

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  20. Thanks for publishing this method. A few of questions.
    1. Can the trees be placed inside the house with central heating instead of outside in the sun?
    2. Why is misting necessary? Surely if there’s water in the pot already and the bag is kept warm enough then it will keep very humid all by itself by evaporation. No water can leave the sealed bag.
    3. Do you add mycorrhizal fungi / Q4 when potting or do you just rely on there being some left in the small amount of soil left on the roots?

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  24. Pingback: Improving the success rate of Yamadori | Bonsai & Yamadori from Tony Tickle | Wolf's Birding and Bonsai Blog

  29. Tony, I find this quite incredible and fascinating. Have you done an experiment to see a comparison of using a clear bag with partial sun vs. black bag and full sun? Is the time of year of significance?
    I find the technique fascinating.

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  33. I tried this almost exact process last year based on rumors it was being done in Europe( probably you). I had similar success with a large old Ostrya (hop-Hornbeam). My soil mix was 1/2″ Perlite and pumice with 15% chopped sphagnum. It is exciting process to use with our hard budding horn-beams and hawthorns.

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