Repotting a Callistemon

Shibui

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I'm not sure whether I've put this tree up on B'nut.
It is one of my early attempts at working with our Australian natives as bonsai. The tree is Callistemon sieberii - river bottlebrush which grows along the creeks and rivers in my area. I first noticed them in situ while looking for gold in the nearby Ovens river. On the banks they grow as larger, upright trees but where seed germinates in the cracks in the rocks close to the water the trees get smashed by flood water every year so all branches are elongated pointing downstream. Upstream side of the trunks are scarred from impacts with flood borne debris. Roots flow over the bare rock to find footholds in the cracks.
Not sure whether similar shaped trees grow along rivers in other parts of the world but I was impressed by the signs of resilience and survival in those trees so I set about growing a bonsai that expressed the same attributes. I've dubbed this waterswept style.

Here's the tree before work today:
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Callistemon flower on the tips of last summer shoots like azalea so in order to see flowers I have to allow shoots to grow freely from late summer then prune back hard after flowering. This tree got a bit dry a couple of times through spring so has not flowered this season and now it is time to prune.
One of the good things about this species is that it sprouts easily from old wood. So easy that new shoots appear, even on very old trunks, without pruning.
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Because I want to show sparse and elongated branches most of these shoots are rubbed off
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The shoots that grew last season are pruned right back to one or 2 leaves or even removed completely knowing that new buds will sprout.
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I've found that early summer is also a good time to repot this species. It has been drying out really quick through spring so I suspect it could need some more space in the pot.
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It tolerates root pruning really well so roots are trimmed back quite hard. I forgot to take that photo though.......
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pot prepared - that's drywall plaster tape covering the drainage holes.

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and back into the pot with fresh potting mix. Like all my trees this one gets my standard bonsai mix complete with controlled release fertiliser.
The tree is back on its stand, under light shade cloth this year. I normally put up the shade cloth after Christmas but the sun was getting a bit hot quite early this spring so the shade went up early.
 

Colorado

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Great bark and deadwood.

Very cool tree! Love seeing species that I’ve never even heard of 😎
 

Leo in N E Illinois

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I love seeing Callistemon as bonsai. In my climate they have to be treated as an indoors for winter, outdoors for summer sub-tropical, which makes them a little difficult. Also means they are not available locally because they are not easy subjects. But I love seeing them.

Thanks for the advise on when to repot. And the news that they bud back well on old wood. This does make them desirable for bonsai.
 

Shibui

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An update on this callistemon just to show that root pruning actively growing Aussie natives in spring is not a death sentence. Remember it is early summer down here.

It is now 2 weeks since I pruned both the top and the roots. The tree has been kept in its normal position. This year I have 35% shadecloth up because it has been hotter than usual earlier than usual. We've just had a week of temps around and above 40C and record highs all over south-east Australia.
I've kept the soil quite damp. wetter rather than a bit on the dry side. It's still sitting in a tray so at times it has had 1cm of water just to make sure the roots don't dry out.

There's now new buds popping out along the smaller twigs.
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Buds also appearing further back along the branches.
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and even way back on the main trunk. I'll have to start rubbing those off because I don't want too many shoots on this tree.
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Cadillactaste

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I love seeing Callistemon as bonsai. In my climate they have to be treated as an indoors for winter, outdoors for summer sub-tropical, which makes them a little difficult. Also means they are not available locally because they are not easy subjects. But I love seeing them.

Thanks for the advise on when to repot. And the news that they bud back well on old wood. This does make them desirable for bonsai.
They can be treated as a tropical? Mine steadily declined when brought indoors. Though it was early on in my bonsai journey. I had a potted hibiscus indoors forever. So if confused me.
 

Forsoothe!

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They should decline, or look like it. The biggest problem people have with tropicals is they treat them like all of them came from a rain forest where the foliage stays nice and pretty all year-around. Most come from wet season/dry season places where they survive by shedding leaves just like temperate plants do in winter. In that case, you have to allow them to go dry with getting bone dry (in most cases). Keeping them wet all winter in the house in the north is just like keeping a temperate tree too warm. That may or may not kill a Hornbeam outright, but without sufficient quiet period below ~34°F, they do not spring back the following Spring. I don't know what the quiet period length or depth of dryness is necessary for tropicals from these wet/dry places is, but if you google the climate for a given place on Earth, you can guess. I think all you need to do is get close. Merry Christmas!
 

Shibui

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I can't offer any advice on keeping callistemon protected from extreme cold. Over here we keep them outside all year round and well watered all year round. Callistemon certainly don't shed leaves at any time of year. They are evergreen and only shed older leaves after a couple of years as pines and other evergreens.
This species at least is hardy down to around -10C. Maybe it would overwinter in a cool garage like some do to conifers? With good grow lights and suitable conditions they should also manage indoors. I'm constantly amazed at the species some of you do manage to keep indoors for the winter. Many are trees that I could not manage to keep indoors here but that may just be because I don't need to learn how to.
 

Shibui

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3 weeks later and this callistemon has new shoots extending to around 10cm an shoots growing on older branches and trunk.
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Time to remove all those shoots growing from the older areas as I want to maintain open feeling for this tree. I also removed shoots from areas where more than a couple were growing then trimmed the remainder back to 1 or 3 leaves. This pinching will produce another fresh lot of new shoots.

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After thinning and trimming new shoots.

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New shoots after pinching.
 
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