Satsuki

[shohin kid]

That's such a strange coincidence, I had the exact same experience: a very old satsuki that I brought from Vancouver, it was in 100% Kanuma. It died after 1 year, here in California.

I grow all my satsuki in 75% coarse peat moss and 25% pumice.

Walter Pall uses 60% substrate and 40% peat in his azalea mix, according to his blog.
Your problem may have been that you used 100% substrate, like kanuma, and once it broke down, probaby due to your climate, it sufficated the roots.

One article I have also read in a satsuki magizene is that kanuma has a bad name in europe and north america because people buy and/or import azaleas in very old kanuma that need a repot and once the tree is repoted into a new kanuma mix that it grows very good. The article says that this gives kanuma a bad reputation.

 

[Glider]

Shohin Kid: I think you've nailed it with the old kanuma point. I've been following this thread because I use 100% kanuma for my satsuki with absolutely no problems. From my own experience, I would say it's actually a bit more resistant to breakdown by watering/drying or freezing/thawing than akadama and it seems to me that it is most usually broken down by the action of the roots, swelling and matting and crushing the granules over the years. I think, if anything, it's fine, hair like roots matting and compacting that causes drainage problems (like hair in a shower plug hole) rather than kanuma being a poor substrate.

I had to perform an emergency repot on a large satsuki for a friend of mine three years ago (it was in the kanuma it was imported with and was showing signs of failing after 1 year, the same as Attila's) and the fresh kanuma I used for that is still absolutely fine. It still drains perfectly (water flows out of the drainage holes as fast as you can pour it in at the top) and still has its texture (friable and granular), and the tree is thriving now too. So, I was curious about the negative perceptions some people have about kanuma and I think you're right; a lot of the problems (and people's negative perceptions of kanuma) come from the soggy crap that nursery satsuki are potted in.

I've never bought a satsuki that wasn't in severe need of repotting. Come to think of it, I've never even seen a freshly imported young (or even mature) satsuki in a nursery that was in good kanuma. Every single one I have bought had a rootball that looked like a soddden, dirty-yellow brick. Each took an hour or so of work to get rid of the old stuff, free up the roots and repot into fresh kanuma, since when they've been growing like weeds (after sulkiing for a year).

I think the commercial nurseries import so many that it just isn't cost effective to repot them (except perhaps the specimen trees). They recieve them in ancient, worn-out kanuma that's years past its sell-by date and it's easier and cheaper just to keep them alive until they're sold.

I do think that when people go to by an imported satsuki, they should be aware that repotting it is very likely going to be at the very top of their 'urgent to do' list.

 

[Attila Soos]

Yes, old Kanuma is a killer. It turns into a yellow block of mud. That's why I switched to peat-moss (the very coarse one, not the garbage that they sell at the garden center). It has the same advantages and none of the shortcomings. Here in California it's ideal, not sure about the cooler climates.

 

[Glider]

That makes sense. I know some people use chopped sphagnum for the same reason (in warmer climates than here). Mixed in with the kanuma, it also seems to provide a mechanical buffer for the kanuma, inhibiting its compaction, which makes the infrequent repottings of mature trees easier.

In the UK climate, I don't need any more water retention than the kanuma alone provides, but I do use chopped sphagnum as a top dressing (about 3/4 inch deep). Over the course of a year, the buldup of moss, old organic fertiliser and other detritus begins to slow down drainage. Replacing the mat of sphagnum in spring takes five minutes and returns drainage to normal. The sphagnum also acts like a filter, keeping crap from filtering down and clogging the root area, which also helps prevent the kanuma from becoming a solid block.

 

[mcpesq817]

That makes sense. I know some people use chopped sphagnum for the same reason (in warmer climates than here). Mixed in with the kanuma, it also seems to provide a mechanical buffer for the kanuma, inhibiting its compaction, which makes the infrequent repottings of mature trees easier.

In the UK climate, I don't need any more water retention than the kanuma alone provides, but I do use chopped sphagnum as a top dressing (about 3/4 inch deep). Over the course of a year, the buldup of moss, old organic fertiliser and other detritus begins to slow down drainage. Replacing the mat of sphagnum in spring takes five minutes and returns drainage to normal. The sphagnum also acts like a filter, keeping crap from filtering down and clogging the root area, which also helps prevent the kanuma from becoming a solid block.

Dave Kreutz gave a lecture at this past May's show at the National Arboretum, and mentioned that he uses yamagoki (sp?) moss as a top dressing on his azaleas.

 

[shohin kid]

Dave Kreutz gave a lecture at this past May's show at the National Arboretum, and mentioned that he uses yamagoki (sp?) moss as a top dressing on his azaleas.

He does, Dave is in my bonsai club and I have been to his nursery. Most of his trees have them as a top dressing.

 

[Si Nguyen]

I agree with the OLD kanuma being a problem. There are different grades of hardness to consider too. But in the USA where there is very little use of it, the kanuma here would sit unsold for a long time. I bought a few bags from time to time, and they are always old and crumbly. With proper sifting, I could get maybe a 10-20% of it to use correctly, the rest is good for only making muck. But I am fairly sure that kanuma do decompose faster in my area due to poor water quality and heat too. I use only a part of it in my mix in order to keep it slightly acidic, which is good for buffering out my bad alkaline hard water.
Putting a mat of moss on is a good idea too. But most trees grow moss so fast, because of the acidity and daily waterings. My trees are covered in green moss in one season naturally anyway.
The one thing I did which I think is most helpful is to age my tap water for a day or two before watering my azaleas. This is good for maples too. This is to evaporate the chloride out of it before watering the plants. I highly recommend this, at least to the people in my area.

Si