Repotting a big maple in August

This is amazing. I trust Walter 100% without question so I am sure that the tree will trive and the results again will speak for themselves. Take a look.


Great tree! It has been one of my favorite deciduous trees for a long time. Just look at it though; it has looked better and is obviously overly vigorous. He is probably doing it to push fresh roots and is, best guess, going to prune it back in the fall/spring… Somebody is going to be watering that tree a lot too. Like Ryan says “it looks like it has reached that point and grown out of its’ design.” I trust Walter Paul too. He has an outstanding eye for getting elegance out of a natural design.

Here’s Walter’s comment on the issue. It is also not an experiment, he’s been doing it for a while and the results are unquestionable.

In Walter’s own words taken off facebook without his permission - which I hope he grants me implicitly:
"Do not cut off too much roots, do not cut off foliage. After care it needs much less than in spring. This is one of the best things about it. The days get shorter, temperatures get down slowly, it rains more, humidity in the air is higher, much more due overnight. Water thoroughly after repotting - everything, also the foliage must be dripping wet. Then water once every day thoroughly, start feeding immediately, tree should not be in full sun all day, rather half shade, sun in the morning and shade in the afternoon is best. You must use modern substrate - absolutely no soil. You must leave the foliage on. Do not cut anything until October. Water every day all over the tree. Only on very hot days water twice. If you don’t have much to do you can mist the tree several times a day. Frost free winter protection is a must.

Why does this work so well and better than in spring? Because the tree has perfect conditions now to grow roots until the end of October. This is why now! Earlier is better than later to have more time for root growth. This is eight weeks and sufficient.

Roots only grow now if there is plenty of foliage that creates energy for that. If you have not cut any branches the terminal buds will send signals to the roots with hormones called auxin that signal to grow. If that signal is not there the roots will hesitate.

The tree must get frost free over-wintering. In next spring it will start as if nothing happened.

If you repot in spring there is no foliage yet to help the roots to grow, the tree must do this out of stored energy. The energy was stored for foliage growth and not for root growth and the tree will be weakened. The foliage in spring will grow into an environment which gets worse every day, days longer, temperatures higher, humidity lower every day. The foliage will find it hard to grow well. It will quickly be too much to be supported by the existing roots - especially if you have cut off many. You have to cut short very soon after the shoots have stretched in order to avoid too much foliage mass which cannot be supported by the roots. The tree is weakened all the time by these measurement. It has a tough first summer after repotting. After two years the same again and people wonder why their trees are not doing well,m why thy do not get anywhere and stagnate."


I love how Walter does things so differently - great stimulus for discussion. One thing i see in his photos from the blog - yes, he removed ~50% of the root mass and somewhat loosened-up the periphery, but he actually left most of the remaining root mass untouched … he clearly did not bare-root the tree - I think this is probably what allows for survival and use of full fertilizer. My thoughts anyway.

Question: does Acer palmatum have a true Shin that it relies on? Because if so, Walter clearly kept it intact…

I seem to remember the Shin being important for some trees, eg pine, azalea, but not others, eg something from one of the deciduous streams - does anyone remember or know which species have a true Shin and which don’t??

PS this is literally the #1 (of two) tree that got me interested in Bonsai, and Walter specifically has been my ‘hero’ forever; love that guy and still waiting to get a chance to visit PA or Il one of these years.

PPS ‘#2’ of the 2 trees that got me into Bonsai is the ‘hiroshima’ White Pine gifted to the National Arboretum … turns out this was actually the initial stimulus that made me read and research more about bonsai - found the original article!:


I’ll be this december at Nature’s Way with Walter and the gang for the winter study workshop. Come along! Yes, his Maple #1 is my inspiration for all deciduous trees. That maple and his other maples are some of the very few deciduous bonsai that look like old majestic deciduous trees. I also really like the story behind the Yamaki pine, not so much its style but it wins not only for having survived the bombing but for the fact that is is in training for almost 400 years.

I think that the issue with bare-rooting is the fact that it would have caused injuries throughout the root system when packing the new soil even if it would have been bare-rooted carefully with water or air to minimize injury. In any case for a tree like this the type and amount of work done is what you would do even in spring. I about two weeks I will bare-root and repot a witch-hazel (Hamamelis virginiana) expecting that I need to perform minimal root pruning and I will leave the second almost identical witch-hazel I have to do spring repot as an experiment.

yes - the 350-400y of trans-generational training is definitely a huge aspect of that story that shocked my interest

1 Like

Walter technic makes sense but anybody else who has done it can comment plz? I wonder what other experts think, one of my biggest concern is worrying the hole winter.