Root pruning Trident maples

[shibui]

Root pruning more established trees is much the same.
Here is a trident about 18 years old. Originally field grown but in various grow pots for around 8 years, mostly neglected but some branch structure has been developed.

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I start like before - cut the bottom off the root ball, trim the layer of matted roots around the edges, rake out most of the old mix then trim off excess fine roots so it will fit into a pot.

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Note that regular root pruning has resulted in lots of fine roots close to the trunk and very few thick roots except close to the trunk - nebari.

Select a pot

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Prepare the pot

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The tree still sits too high. The root ball is too deep so I had to cut some more off the base.

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The problem was some callus that had formed where large roots have been removed in the past. Cutting downward roots when they were quite small would probably have prevented this. Note that I can't cut back much further because it has now been cut back to the base of the trunk. Most of the remaining root ball is solid wood.

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then water in and return it to the growing bench.

[matty-j]

Great post!

Thanks for taking the time and effort, it's much appreciated!

Cheers
Matt

[Josh]

Thanks for showing the work on a more mature tree. I have a larger tree I'm about to pull out of the pot for the first time since purchasing so have no idea what the roots are like but want to start getting them sorted and work on nebari so this has been very helpful. Thanks for taking the time to share.

Josh.

[Isitangus]

Hi Neil I have a trident I plant to take multiple layers off come the right time-should I still root prune now? It is in a large nursery pot and has not had a root chop for the last two years.

[shibui]

Angus, Most people would probably say to not cut roots when you want to have it grow strongly - for air layers, etc. In the past I would have agreed because this is conventional wisdom handed down by generations but I am rapidly changing views. For a long time I have noted that my bonsai grow significantly faster in the summer following repotting. Others report the same thing. In the latest Bonsai Focus in an article titled "Let it heal" I note a caption on a picture of pruned roots (bottom of page 61) -

The top section of the tree has hardly any branches or foliage. In order to assist the vigorous growth of branches the roots are also pruned back hard. Planting it in slightly larger particle soil and giving lots of fertiliser and water will expedite the growth process

Looks to me that Japanese bonsai growers also recognise that trees grow faster after root pruning. This should mean that it would actually be beneficial to repot your tree so that it will be growing strongly when you put the layers on this year! We just need to get past this mindset that pruning roots will slow growth and stunts trees

[Isitangus]

Thanks Neil, I'll give it a root prune and then set some layers

[dan.e]

Thanks Neil much appreciated if it has already started growing is it to late?

[shibui]

I'm not sure it can be 'too late' for repotting Dan. Most growers will tell you that repotting maples while they are growing will result in certain death of the plant but I have proved that tridents, at least younger plants, just keep on growing. I have also repotted tridents when buds were just barely open with no problems. I still prefer to root prune my deciduous trees while they are dormant but I would still repot tridents, probably with just a light root prune, if they had leaves half open.

In the end it is up to you. How urgent is the need to repot? How advanced are the trees? How brave do you feel?

[MoGanic]

In the end it is up to you. How urgent is the need to repot? How advanced are the trees? How brave do you feel?

Question 4; what sort of after care can you provide?

-Mo

[Elmar]

Do these species need training to be able to survive this amount of cutting back or are they adapted to dealing with it from the get-go?

Turn, thank you for sharing your video, do you have 2 sets of tools, one for cutting roots and one for leaves & stems?
I'd imagine cutting thru soil would blunt the tools so not making them ideal for use on trimming the upper part if the trees...


Cheers
EZ
Via Tapatalk

[shibui]

Do these species need training to be able to survive this amount of cutting back or are they adapted to dealing with it from the get-go?

Interesting question. I had not considered it before but thinking now i have constantly been saying that radical root cutting from very early promotes lots of finer roots rather than a few bigger ones so I suppose we do 'train' our trees for root pruning however, I have often dug trees that have had little or no previous root pruning and cut roots back very hard. Lots of the tridents that came out of the growing beds had roots 3 cm thick that were cut back to just 3-5 cm long leaving a trunk that was little more than a giant cutting. They almost all survived so i think the answer is probably that many species are just naturally able to survive this sort of treatment.

[milly.abrahams]

Thanks for the time and effort involved in creating this great thread Neil

Regards
Milly

[Laurie J]

Thank you for creating this! I'm planning on getting my first Maple soon, so I know I'll be coming back to this again and again!

[Waltron]

I don't feel so bad after reading this now, I basically flat-bottomed a trident maple in a fit of despair over poor roots about 3 weekends ago. It ain't a youngin' either. Fingers crossed!

[Isitangus]

Yesterday was d-day for my Trident-time it's it's first major toto work in my hands. You know when your cutting, and cutting, and cutting, and you think surely that's too much-then the little voice on the other shoulder says "not enough-remember Neil's pics"! So off went more. It's amazing the amount of roots these bad boys put out. Anyway attached is a before and after pic. Not great pics but enough to get the idea.

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the end result-and ? New front.

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almost there but still lots to go

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before in oversized nursery pot

The next question is how long until until I can do this to me corky bark elm? I know they say late winter-it's pretty late and pretty cold!
I must admit I did this in open view of my other bonsai's as a warning of what may come their way!