Grafting Hinoki on Thuja (Arborvitae) Part 1

Many people think that the foliage of Thuja is untameable and unsuitable for bonsai. This is not true – a very refined image can be produced with the native Thuja foliage, especially for medium to large bonsai.

However, there is always the possibility of grafting the more fine hinoki foliage on if you are truly dissatisfied with the native Thuja. The two species are, after all, quite similar. While hinoki has better foliage characteristics, thuja has better vigour and wild specimens have incredible deadwood features. When I showed pictures of my collected Thuja to Junichiro Tanaka (owner of Aichi-en in Nagoya), he described them as “Hinoki Juniper”.

But even though I am content with the native foliage, sometimes grafting is necessary. Take this tree as an example.

When it was collected, I planned on building the bonsai from the branch closer to the trunk. The longer section was to be cut off when the tree recovered.

The long, far away section of foliage had no purpose for the bonsai design.

Why didn’t I cut it off when I collected it? Well, I’m not totally convinced by the “balancing the roots with the shoots” idea. It seems like common sense that leaving more foliage will give the tree more strength to produce new roots, as long as you can minimize transpiration with misting.

Well, it looks like I ate my words here. The most important branch died, of course. I think this is because the roots supporting it were damaged when collecting. Cedars have a very “divided” lifelines that are distinctly attached to roots. If I killed the roots that supported that branch, there was not much hope.


The trunk is nice enough that the tree is worth setting aside as a grafting project. I have never grafted cedar, and this will be an exciting project for this year (and maybe a few years to come). Nick Lenz has a “hinoki cedar” that is rather famous in the Eastern North America. It took him something like 4 years to completely replace the thuja foliage with hinoki. I believe he used thread grafts for this (yes I know… sounds insane) and Chamaecyparis obtusa ‘Nana’ (dwarf hinoki).

An older picture of Nick Lenz's "Hinoki Cedar", created by grafting Dwarf Hinoki onto a collected Thuja occidentalis trunk.

I am not planning on using thread grafts, nor am I planning on using Dwarf Hinoki. I will try two types of graft – approach graft and bud graft using Chamaecyparis obtusa ‘Kosteri’. This variety seems somewhat more vigourous that ‘Nana’. The foliage is not as compact, but it is still very fine, dark green, and somewhat less curly than ‘Nana’. Hopefully the greater vigour of Kosteri will accelerate the grafting process. Check back soon for updates.

'Kosteri' Hinoki foliage.

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  1. Pingback: Grafting Hinoki on Thuja (Arborvitae) Part 2 « Lakeshore Bonsai: Bonsai in Toronto, Canada

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