Hi.

I am also trying to grow my own bonsai (a red Japanese maple)

I have not been growing it all that long but I have put it in some bonsai compost and I feed it with the special bonsai feed.

Although it is early days, it is looking really well and healthy, I only feed it about once a month as I am growing it outside.

Personally, I would recommend this method.

Hope this helps.

Kind regards

Shelley