AusBonsai

Dear Bonsai experts
I’m planting my first Casuarina equisetifolia (Austrailian pine) from seed and hope you can give me some care tips. It’s going to stay indoor for practical reasons.

Can you especially say something about: when and how to prune?

A big thanks in advance.

Like other casuarinas prune when it needs it.
Initially you can let them grow long to get the trunks to thicken. Casuarinas usually bud on old, bare wood when they are pruned so you don't need to worry about how large or long they grow. You can cut back any time.
When you start to form branches you need to prune more often. I have been shearing the new green stems whenever they grow more than about 4-5 cm. New shoots will grow from the nodes and the branches quickly get thicker and bushier.
It does not seem to matter what time of year you prune but obviously they will bud and grow back quicker while they are actively growing during the warmer months.

I hope yours will survive inside. I suppose it would be too cold in winter for them to survive outside. You will need to maintain good conditions and be very careful with water, temp and humidity.

Hi Shibui
I send you many thanks for your detailed response. The Australian pine will be my very first bonsai – perhaps a silly starter-choice but the choice has been made, so I must get the best out of it.
Every help is treasured!

So pruning the Casuarinas is “only” for shaping/limiting the tree? On other species I’ve read that pruning is also done for instance to limit the leave size.
Do you cut the stems at a specific place or just the 4-5 cm from the branch? Some pines must be cut where there is a gap between the new and the old needles (so I’ve googled).

Can you do something to limit needle size and increase the “miniature-look” of the tree? Some species can be defoliated.

Lastly regarding water, temp and humitidy: I’ve read that you should keep the soil moist. I plan to place it by a sunny window in our bedroom (aprox. 22 degrees Celsius) and make sure to ventilate the room regularly. Does that sound okay?

I have never tried to grow casuarina inside. We only grow these outside in natural conditions so I am not sure how they will grow for you.

Casuarina is not really like any other trees. The leaves are tiny. You can only see them with a magnifying glass. The green part is actually the stem of the tree. Pruning will gradually make the stems shorter and build up some good branches but the first thing is to grow a trunk.
Normally we let the tree grow wild for a few years until the trunk is thick and has a good shape. Then we start to select some good branches then grow some twigs and leaves on those branches. it will take quite a few years.

Casuarina is not like a pine. casuarina 'needles' are actually the stem of the tree. They are divided up into joints where the tiny leaves are. To limit the length of those stems you can cut anywhere or you can pull the stem apart. The stem will break at a joint. Just keep trimming or pulling whenever the stems get too long.
Language may be an issue. I said when the stems grow about 4-5 cm long you can trim them back to make shorter - cut back to say 2cm to make the tree look neat. Trim shoots whenever they get long and look untidy. This is the way to increase the miniature look of casuarina.
This thread has some pictures and explanation of how these trees really grow - viewtopic.php?f=56&t=24470&hilit=+casuarina+stem

Thank you SO VERY much!!!
You have been a huge help. I’m looking forward to get started.

PS. I live in Denmark. That’s why I plan to grow inside.

PS. I live in Denmark. That’s why I plan to grow inside.

I noticed your location on your profile hence the comment about cold winters.
Not all trees like being inside a house. Light levels are never the same as outside, humidity can be very low in winter when heating is on, etc so some species cannot cope. I hope you can manage these casuarinas inside.

Indoor plants tend to be rainforest type plants that are adapted to low light and variable humidity. When someone wants indoor bonsai I usually recommend ficus because it is very tough and is known to grow indoors without any problem. Ficus are frost tender so we bring them indoors for the winter to protect them from cold over here when the temp gets down close to freezing.
US bonsai growers have done more with indoor bonsai and may have more advice about what species are good and what conditions to provide that will give more success.

Removed... Posted in wrong thread... Sorry

The tree in the centre is not casuarina. Looks like some sort of legume and I think one of the other species you grew was a legume species? Maybe the one on the right, almost out of the shot is casuarina but still a long way to go before it gets big enough to do something with.
Well done on getting them this far in your climate.
It is starting to get colder here at last so assume it is now warm in your part of the world?

My 6 month old inddoor Casuarina equisetifolia (from seed) is beginning to look reddish and quite poor. Does anyone have an idea of what's going on? Is it okay, and is there something I can do? It happened after I moved it to a larger pot (and pruned some roots)

Casuarina normally handle root pruning well, especially when it is done during the warmer months. Looks like the red is mostly older parts. Could be due to a number of reasons:
Nutrient deficiency. Has it been fed and with what?
Root problems - root rot due to wet mix or some other pathogen in the potting mix.
Lack of light.
Some species just do not like to be inside for extended periods. Maybe this is one of those and is struggling with conditions inside.

Older parts do die naturally as they are replaced with fresh new growth but I would expect older parts to last longer than 6 months.

Without a better look at the plant and some discussion about conditions I can't really give any suggestions, Just

In my opinion shibui is spot on. Your tree doesn’t look good.
If you address the issues Neil has advised you of, it should come good.

Those were the exact problems I’d be checking for too if it was mine.
I’ve never tried to grow casuarina inside, I can’t imagine it would be easy.

If that tree is only 6 months old and growing inside you are doing quite well with it. I agree with the above statements. I would like to know too, how does the top look? It may be shedding older stems as it adjusts to the repot or natural attrition of the older stems in favour of growth higher up. Especially if grown in low light.

Thank you very much everyone.
I feed the tree with slow release NPK 5:5:5 but it's a month since now.
The top isn't really growing. It's just getting red from the buttom and slowly up.
It gets a lot of light.
I think I will try to replace the soil and see if the potential rotting will stop...

Thank you all!!!!

So I changed all the soil and gave it som fert and it recovered!!
Here is a brand new Picture... It's already about 50 cm tall and needs to be cut down soon (regarding lack of Space).

How would you start pruning?

Well done on keeping this alive, especially indoors. I think that is quite an achievement.
Casuarina are quite good at growing back after pruning. You should be able to cut the trunk anywhere above some green growing parts and it will continue to grow. You can also just cut the ends lightly and it will start growing again somewhere just below the cuts.