Satsuki Azalea

pwk5017

Hello everyone, i hope everyone is enjoying spring. I hate to clutter this board anymore with a question but i am desparate. I have been involved in bonsai for about 3 years and i have a problem with my satsuki azalea that i purchased from a bonsai nursey last june. The tree is out of dormancy and has a few leaves out, but 3 of these have curled under and turned brown, then fallen off. It was overwintered in my greenhouse and might have come out of dormancy a tad early. I have had it outside this past week and a half due to the nice weather. I am not sure if it is a question of overwatering(i have a feeling im guilty) because i dont know if azaleas should be kept moist or dry. The only other problem i could think of would be the colder night temps, they have dropped around 40 degrees. Unfortunately, i cant post any pics tonight cause i do not have my camera but i will tomorrow. I hope someone can recognize this as an obvious problem.

with thanks,
Patrick

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Glider

Really, a bit more information is needed. What medium is it potted in? How long has it been in its current pot? what are the nighttime temperatures there?

In answer to your question, azaleas should be kept damp (rather than moist). They don't like wet roots, but should absolutely never be allowed to dry out. Their roots are very fine and hair like, and drying will kill them very quickly.

The reason the questions above are important is that azaleas are prone to 'capping'. Due to the very fine nature of their roots, if they are not repotted properly, but just have the rootball reduced, the area of root around the base of the trunk can become very compact and, in effect, waterproof. Thiis compact area of root forms a cap that water will just run off. As a result, the centre of the rootball begins to dry out as the water just drains from the sides.

You can solve this problem in the short-term by watering by immersion (dunking the pot in water up to the base of the trunk). However, if the problem is that the roots have been too wet, this will not help at all.

Satsukis are quite hardy and can easily withstand temperatures of 40 degrees (F). That's above freezing, so it's unlikely to be a problem. Generally, if there is a problem with satsukis, it's more likely to be with the roots than anything else.

Azaleas are a lot tougher than many people give them credit for. Their roots are their Achilles heel though. If you can keep the roots happy, the tree will grow like a weed. It's not too late for repotting either (if your local conditions are anything like mine, in London). I think, if anything, you probably have colder and slightly longer winters in Pennsylvania than in London.

So, if it is a problem with the roots, you could still get away with repotting now. You need to use an open, free draining mix that holds water well. I suggest well sifted kanuma, but I don't know if you can get it there. Avoid peat though. It stays far too wet.

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pwk5017

Yeah i agree with you on the roots thing, they are finicky. Anyways it was potted in a terrible mixture, sand and peat. Talk about holding water forever. I was going to repot it when i went home(currently at school in State College, Pa) after it bloomed and everything, but it is just such a terrible mix it is planted in. I dont have alot of potting stuff with me currently though. I have several pots that would work for it and in terms of potting mix all i have is perlite, some finer pine bark, and small stone(1/8" in diameter). I think something can be whipped up with the pine bark(acidic) and the perlite(drainage), but what do i know? I have little experience with these plants so i am definately ready to listen to everyone and anyone. By the way, thanks alot for the opinion glider.

Glider

You should be able to make something out of those ingredients. Aim for a more open mix than you 'feel' is suitable though.

Because azaleas like their roots consistently damp, many people put them in a closer mix that holds more moisture. This is a common mistake (and one I made too when I first started with azaleas), and is one of the main reasons azaleas got their reputation as being difficult to care for.

In reality, azaleas like a lot of air around their roots. They are, after all, a very shallow rooting plant in nature. As long as that air is kept damp, they'll thrive. So, for bonsai, they like deeper pots than other trees (keeps the roots cooler and provides a buffer against sudden drying), but with a more open mix but that holds water well.

This is why kanuma is unbeatable for azaleas. You can make a very open medium that allows a lot of air by using granule sizes around 10mm, but each granule is porous and holds a huge amount of water so the air never dries out. Azaleas go nuts in those conditions.

For my other trees, I use only akadama (personal choice for convenience), but I'd quite happily use any of the recipes you see on this forum. But for my azaleas (with their unique type of roots), I don't think I'd use anything other than kanuma. Well sifted at 10mm, it provides exactly the conditions azaleas require and so anything else would simply be an attempt to reproduce the qualities of kanuma.

__________________
Experience is knowledge gained immediately after it was needed.

TimD

I always look to the roots when checking out problems with my Azaleas. Could these leaves be last years leaves though?

Theres a little description on this site below. It's not a bonsai site so not everything pertains to growing them as bonsai.

http://www.azaleas.org/faq.html#lea

pwk5017

Yeah it has to be the roots and too much water combined with the heavy peat and sand mixture. Im going to repot it and hopefully i wont find cases of root rot. No last years leaves are all gone these were fresh leaves about a week old. Nice site though it does have some interesting info.

MattO

"Well sifted at 10mm, it provides exactly the conditions azaleas require "


Glider, 10mm is almost 1/2 inch in diameter. Are you telling us that you use grit THAT large for any plant?

bubbafrga

I use 90 % crushed volcanic Rock with 10% pine bark compost.

Mike Rodgers, Bonsai Societies of Florida Artist uses 100% crushed volcanic rock for all of his azaleas.

Glider

Not grit. Kanuma.

Yes, I use 10mm kanuma granules for all my azaleas. Years ago I used to use well sifted kanuma straight from the bag, but most kanuma you buy online is quite small (from 2mm to a max of 10mm). I would use a 2mm mesh to sieve out the dust. However, my azaleas never did well and some eventually died. I only had 5 to begin with and I lost 3 of those. I tried everything else I could think of, but nothing helped. They just would not take off.

Some years ago, I got to know a guy called Ken (he owns Windybank bonsai in Surrey). He's an absolute mine of horticultural info on azaleas. He has a close working relationship with azalea growers in Japan (and is fluent in Japanese) and goes there every year. I talked to him about azaleas and that's when I found out their particular preferences (and also that 'satsuki' is actually pronounced sat'ski ).

With the mix I had been using (2mm to 10mm), the 2mm particles fill all the spaces. It's too close and there's too little air, especially when the roots begin to fill what little space remains.

It's the defining characteristic of azalea roots. They don't grow like the roots of other plants, they form something more like a 3 dimensional hair blanket that can clog their own potting medium and reduce drainage and air flow to nothing. They're literally like hair, and you know how that can clog a plughole.

So now I won't use anything less than 4mm and I only use that (a 4mm to 10mm mix), in the layer directly around the roots. Below that I use only 10mm granules, even in comparatively small pots.

In the long-tom pots (which I use for growing azaleas on), I use larger (15mm) granules in the bottom third of the pot to reduce the perched water table. I use a very fine layer of 2mm as surface dressing only (for appearance and to help buffer it against drying winds).

The proof of the pudding, as they say, is in the eating. Since I changed the size of the mix, all my azaleas are going nuts. I now have 20 (12 satsuki, 3 kurume, 1 hyde, 1 kaempferi, 1 Satschiko, 1 gabrielle hill (North Tisbury), and 1 Kuwano), 17 of which are growing on in long-tom pots and they're all going crazy.

I no longer consider azaleas to be 'difficult' or 'temperamental' plants to grow. They're tough as weeds and just as resilient. You can root prune them to within an inch of their lives (which in a few cases I have had to do, either to correct my previous error, or to get rid of that awful, claggy garden centre mix), and they'll cope, as long as they're put in the right mix afterwards.

The downside is that no online shop I know does kanuma bigger than 10mm and so you end up throwing at least 50% away. Windybank is the only place I know that sells bags of kanuma from 4mm to 20mm size (he imports it specifically, because he knows better), so, I have to take the train to Surrey each year and carry back as much as I can (happily, it's very light so I can carry 6 17L bags ).

The golden rule: Azalea roots need lots of air. Always damp, but air, not water.

__________________
Experience is knowledge gained immediately after it was needed.