AusBonsai

Hello! This is only the second time I am using this to ask bonsai questions. Hopefully I am asking in the right section!

I bought some maple seeds from the Easter show this year and after keeping them in hibernation for 10-12 weeks I planted them in some pots. Much to my happiness a few of them have been growing spectacularly. One in particular is getting very large!

I see lots of tutorials showing how to prune baby bonsai, but nothing on maintaining them when they have yet to form a trunk of sorts. One of these maple sprouts is growing very tall, and I am curious how to should take care of it. Should I be cutting it (if so where?) Should I not be shaping it so early? Should I just let it keep growing until it’s shoot hardens into a trunk?

Any tips would be lovely, as I am very green when it comes to bonsai. (Sorry if this bonsai looks like a monster to the professionals!! I have been trying out different shapes with all the shoots that have been growing).

Firstly, it looks to be growing very well so that is a plus. I see you have put a bit of wire on it and that is fine but keep an eye on it to ensure it doesn't mark the trunk. For maples in the growing season I would usually leave wire on no more that three months but all situations are little different. Every time you water is a good time to check the wire.
Other than that, if it were mine I would let it grow without cutting until autumn (when the leaves have just dropped) and then consider my options again.
Good luck with it.

Congrats on getting your seedlings to this stage. From your mention of the Easter show I guess you are somewhere around Sydney. Conditions vary quite a lot right round Australia so to get better advice you should add a location to your profile which will show up each time you post and remind other members of your climate zone.

There are lots of different ways to approach developing a bonsai. It can depend on what size/shape/standard of bonsai you are aiming to grow. It can also depend on how many years you are willing to put into the development phase.

If you will be satisfied with a skinny trunk 'Mallsai' like most of the nurseries sell you can develop the tree in a small pot like you have now and just trim the long shoots whenever they get too long. New shoots will grow below the chop and each time you prune you'll get more and more shoots to produce a bushy canopy. You can prune any time of year without hurting the Japanese maple.

Growing a tree in a small pot does limit the amount of growth and therefore trunk thickening. It could take 10-20 years to get a trunk 3-5 cm thick in a small pot like this. many of us have learned that it is far quicker to grow pre-bonsai in larger pots or in the garden for a few years. We can develop the same sized trunk in less than half the time.
The vast majority of my Japanese maple bonsai have been developed by grow and chop. There is not really much point wiring the trunks when they are so little because I usually cut most of the original trunk off after a couple of years and regrow from a lower branch which gives me better trunk taper as well as better bends in the trunks.