Question about Karuna for Satsuki

penumbra

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So I have become very intrigued by the Satsuki azaleas i have seen on this site and after many years of using them in landscapes, I am now buying a number of them for bonsai and for stock plants. In every attempt to do it right I just bought a bag of medium 5-10 mm Karuna. I was so surprised by how soft this material is (easily crushes to powder between fingers) that I went into the archives to research it. Apparently it is a whole different animal than anything else I have used but I am prepared to go forward with it.
There is no question that this medium size karuna will find use for my one gallon plants and larger, but I have just purchased several satsuki in 4 inch pots and I wonder if this size is too coarse. Other options are small size, 1.5 - 5 mm, and a Shohin size, 2-3 mm. Also, I am considering adding chopped New Zealand Sphagnum moss. Any other supplements?
Looking for you opinions.
Thank you.
 

Brian Van Fleet

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I use straight kanuma for azaleas. Sometimes I’ll add a little lava rock, often Ill top-dress with sphagnum moss.
Kanuma is soft, so it doesn’t need to be worked in aggressively, but it will hold together in a pot for quite a while.
 

penumbra

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There is no question that this medium size karuna will find use for my one gallon plants and larger, but I have just purchased several satsuki in 4 inch pots and I wonder if this size is too coarse. Other options are small size, 1.5 - 5 mm, and a Shohin size, 2-3 mm.
Thank you for your response. What about this?^^^
 

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Thank you for your response. What about this?^^^

Sorry, yea 5-10 mm kanuma is probably going to be a bit large for little trees.
Id go for the 2-3 mm size myself (in fact I think that is what I have iirc)
 

penumbra

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Sorry, yea 5-10 mm kanuma is probably going to be a bit large for little trees.
Id go for the 2-3 mm size myself (in fact I think that is what I have iirc)
Thank you so much. I was leaning in that direction but at $50 a bag I wanted to be sure.
 

Deep Sea Diver

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Most of my azaleas are in the smaller category….

After using Spaghnum with kanuma and straight kanuma I shifted to use about 90% 3-5 mm kanuma and 10% similar sized pumice for most of the pot with a thin layer of medium size kanuma on the bottom.

Personally I find this mix makes the media more friable with no noticeable drying effect to those I have acquired that are still in straight kanuma. I’ll know more when I doing some repotting of those trees with this this new mix.

Cheers
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penumbra

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After considering this information and sharing information with others regarding karuna, nay or yay, I just planted 12 azaleas, 2 each of 6 varieties of satsuki as an experiment. Six are in 100% karuna and six are in an organic mix of pro mix (Peat and perlite) and pine bark. Tomorrow I will number them and measure them and wait and see. This is not a bonsai mix and the goal is to grow them out for cuttings and as future bonsai down the road. Some will be planted in the garden in a few years.
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penumbra

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Oh I don't feel bad. I never had reason to look into it until a couple weeks ago when I went satsuki crazy.
 

bunjin

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I did a growth test a few years back using eight Satsuki cuttings from one cultivar using four different soil mixes( 2 in each). The test lasted 4 years and I repotted them once in the middle of the test. I am undecided on publishing a results blog due to the fact that the sample size was really not large enough, the photos did not show the details with enough resolution, and most of all, I did not control the lighting and irrigation to any kind of scientific standard. lt did tell me what I already knew, namely that pure Kanuma does not work with my water. Also peat and perlite works okay with frequent repots. Hopefully your work will reveal some useful information for your particular situation. For me just eight specimens got to be a chore and to do a proper sample size would be a huge task for a hobbyist. - G
 

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Some good stuff here folks. I applaud your efforts to develop trails of various media side by side and am interested in the results.

Some thoughts…

There is one thing I would like to point out in a kanuma vs peat/perlite trial. Thus that kanuma contains pretty much no nutrients or microbes. It’s basically a layer of evolved volcanic rock that is baked during processing.

The trial would begin with the peat and perlite mix having a really big head start over the kanuma as a media.

That’s because

- the peat and perlite rhizosphere will already be inhabited with a large amount of microbes from the peat and evolve very quickly vs the kanuma. This is important because the mycorrhizal and bacterial interface is what helps an azalea to intake nutrients.

- there already are nutrients readily available in the peat/perlite to fuel the rhizosphere.

- the kanuma azaleas having their roots cleaned of old soil.

My observation is that, for me, it has taken about 3- 4 months from cleaning an azalea’s roots of the standard nursery mix of peat and perlite and repotting in kanuma before the plants begin to thrive…. That observation is from 30 repots of 24 different cultivars we did in February 2021 Of these 3 didn’t respond at all and two are just plugging along. The rest are now exhibiting vigorous growth, flowering and pushing new extensions.

That’s where the 3-4 months came from. That length of time may be partially due to some root damage during cleaning and regrowth.

cheers
DSD sends
 

penumbra

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My plan is to innoculate all the plants with a bio active fertilizer.
 
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It won’t help,you’d be better off not spending your money of these products and letting the natural mycorrhizae do the job.

Let me step aside and point out this WSU Extension bulletin on Mycorrhizae. Page 4 left side.

I hope this helps.

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How effectively do local mycorrhizae populate pots, especially if they're not kept on the ground? The WSU paper mentioned is talking about ground-growing specifically.

I got a Japanese Black Pine in July last year that I kept on the ground and when I repotted this year I didn't see any visible mycorrhizae, so I'm curious.
 

Deep Sea Diver

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Myco will inhabit pots fine as long as they aren’t nuked as described in the article. Many folks have reported pine myco in bonsai pots. Callahan had satsuki root samples sent to a lab and and the results were positive. However he noted pots could be an unfriendly environment depending on the horticultural practices being used.

btw, Azalea myco hyphae aren’t easily visible, unlike those species in bark and in pine pots which are easily visible.…. at least in kanuma.

Thats brings up a good question though and worth persuing further. I’ll check in the pots of a couple of the test whips I’m growing out in peat and perlite when I get a chance to see if the hyphae are visible in this media. Usually all I see is a tangle of fine azalea roots.

cheers
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