Category Archives: repotting

re-potting Callistemon ‘waterswept’

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December is summer in Australia so here at Shibui Bonsai it is time to re-pot some of my native bonsai and potensai.

I started the day with my Callistemon ‘ waterswept’ bonsai. This one was slip potted into the current pot a few years ago but has not had a proper re-pot for quite a few years. It has finished flowering so it was time to stop procrastinating and get on with it.

before

 

Here is the tree before. The design is based on trees that grow in the bed of the nearby Ovens river with roots clambering over the rocks in midstream and all the growth battered downstream by frequent floods.

 

 

 

 

spent flowers

 

This one only produced a few flowers at the top of the tree this year. All the flowers have finished so it is a good time to re-pot.

rootball

after re-potting

After root pruning it was re-potted back into the same pot.
Potting mix is my standard mix with standard osmocote added.
I forgot to take a picture of the rootball after root pruning but the pile of old mix and roots I cut off will give you an idea how much the root ball has been reduced.

after pruning

After potting the tree back into its pot it has been given a final trim to remove the old flowers and any excess branches.
To get flowers next summer I must now leave the new shoots to grow and mature because Callistemon flower only on the shoots that grew the previous season.
Finally the tree is given a good soak in water then put back on its stand which is in full sun most of the day.

 

banksia proteoid roots

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Summer is also time for repotting many of our Australian native plants. I was repotting some banksias and came across this interesting phenomenon.

We hear so much about Australian Native plants being allergic to phosphorus and needing very careful fertilising. the truth, however, is that only a very few Aussie natives are sensitive to phosphorus and there are also a few plants from other parts of te world that are phosphate intolerant as well. I give most of my Australian natives the same fertiliser that I use on the exotics and they grow very well on it.

The exception is Banksias and here is the reason

proteoid roots on banksia

That white patch that looks like fungus is actually a patch of specialised roots called proteoid roots that have evolved in some of the proteacea plants to help them extract phosphorus from the nutrient poor soils they tend to live in.

a closer look

 

 

Looking a bit closer you can actually see the hundreds of tiny white root tips that are all collecting every available scrap of phosphate from the soil.
And that is the problem. When we apply phosphate rich fertiliser these tiny, super efficient phosphate absorbers continue to grab all the available phosphate. That results in a phosphate overdose and  a very quick death for your banksia so be quite wary of what sort of fertiliser you give to your banksias.
Banksias do not NEED proteoid roots and when they are in an environment that has adequate phosphate in the soil they do not develop these special roots. If we slowly incease the amount of phosphorus in the soil the tree will gradually shed any proteoid roots and can then tolerate normal amounts of phosphate fertiliser but as soon as the nutrient levels drop off again the plant will again grow more proteoid roots and will be sensitive again.
When repotting banksia bonsai most of the proteiod clusters are cut off but that will not hurt the tree any more than normal root pruning hurts any other species.
I do not want to give the idea that banksias can grow without any fertiliser. When grown in a pot nutrients are quickly leached out of the potting mix by regular watering so even banksias need regular fertiliser but its best to play it safe and use a low P formulation.
Many of our banksia species make excellent bonsai. They will shoot on old wood when pruned, They tolerate root pruning very well (in the warmer months) and continue to thicken even in the cramped confines of a bonsai pot so try some banksias for bonsai, just be careful what you feed them.

Is it too late to repot my…..?

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This question is regularly asked by beginners in bonsai. The answer given is usually along the lines of ‘repotting deciduous species must be done as the buds swell and before the leaves open.’

For many years I have stuck with this repotting rule but recently have started to question its validity. Sure it works but is it entirely accurate? Some new information has indicated that this rule may be far more prescriptive than necessary. Continue reading →

Repotting Aussie natives

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I love bonsai and I’m also passionate about Australian Native Plants so it was natural for me to try to grow Aussie natives as bonsai. Originally I tried to use the Japanese timing and techniques and had many abrupt failures so gave up on natives as bonsai for many years. More recently, information from committed growers has led me back to growing natives as bonsai. Word was spreading that many of our natives dislike having roots pruned in the traditional winter/ spring period but thrive when repotted during the summer. Several years ago I set out to confirm this with a series of trials. Continue reading →