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.
- Collect as much root as possible
- Clear as much mountain soil but do not wash the roots
- Use the soil mix as shown below
- Clean cut the major roots as close to the trunk without spoiling the nebari
- Place the tree in the smallest container possible
- Ensure that the tree is well packed in the container
- Wire the tree securely in the pot
- Make sure that the cut branches are clean and NOT SEALED
- Saturate the soil
- Pile fresh sphagnum moss on the surface of the container
- Wrap the whole tree in a VERY large black plastic bag
- Place in a sunny position as the tree MUST GET HOT
- Humidity in the bag must be high at all times, mist spray daily
- After two or three weeks new buds will appear particularly around the cuts
- Ensure that they do not touch the sides of the bag.
- 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.
- 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.
Occasionally the banner at the top of this blog shows this cascade Prunus Spinosa in full leaf on a Barbed Wire stand. When it was exhibited at The Noelanders show on 2012 it cause a wee bit of a stir. That photo is as the tree looked two years ago. A year later I transferred the tree into a larger pot to let the roots run free and build more vigour yet the opposite happened, I slowly lost vigour in the bottom branch. Another year in the pot to see if it would pull back, it did not, the top went from strength to strength… So here is the tree repotted, at a slightly different angle and without the bottom branch.
The branches that remain will not be cut back until the tree flowers in the next couple of month; they are a bit random as I left the tree to recover vigour.
I will need a rather special table now as the trunk slightly undercuts the pot!
I sell a lot of native European Yamadori all of the trees are very old and of the best quality, trees that I would have in my own collection. I select trees on the hill that I believe will make great bonsai and leave those that have no or little potential. With every tree except pine I bare root, removing all the mountain soil and replace with my own mix suitable for growing new roots and establishing the tree in a pot. I also endeavour to plant the tree in the smallest container whilst still maintaining the future health of the tree. This makes transplanting to a bonsai pot a lot easier without the usual dangerous root ball reduction that sometimes takes place after establishing.
Usually the planting position in the ‘training’ pot is not the ‘finished’ angle or position that the tree will be styled, when purchasing I advise one ‘what’s happening below the soil level’ so that future ideas and possibilities can be explored with confidence.
When purchasing yamadori it is crucial to let the tree acclimatise to your local conditions, garden, weather, elevation etc. and not start work on the tree the moment you get it home.
These photos are from a Prunus Spinosa (Blackthorn) after two years in the pot. My student had this tree for 12 months prior to bringing the tree to be potted in the bonsai pot. It was full of new fine roots, the student had fed the tree well and did not cut back or ‘style’ the tree in any way. The tree responded well and when potted on into a Bonsai Pot retained a lot of new root. NO wiring of the branches too place only cutting back to two buds. The tree will deliver flowers and an abundance of new growth this season. Patience always pays off when working with yamadori.