Trident maples (Acer buergerianum) are a great maple for bonsai and I have been developing this one for around 6 years after purchasing it back in 2014 from Lodder Bonsai. Originally it had a limited crown with no real ramification but I liked the trunk movement and thought it has great potential to develop. I have enjoyed progressing the crown with the help of Lee Verhorevoort at bonsai club workshops and know it still has more progress to make. I have tried it in various pots and Lee sourced the latest blue scalloped pot from Japan for me.
One of the main things I have found with Trident maples is that they are very fast growers, they produce a good level of growth each year and this needs to be managed in order to develop the ramification. I tend to leaf pluck the larger leaves most days once it has fully flushed taking off the largest leaf each time I walk past. This is a less stressful defoliation process through minimal but regular leaf removal as opposed to a full or partial defoliation. The removal of the larger leaves encourages new leaves to be produced and over time the density or number of leaves increases while the overall size of the leaves are reduced. Once this process starts though it is also important to thin out the crown density to avoid losing the back buds on the branches through lack of light. Prior to that once it starts to flush in spring I also pinch out the elongated tips to let the next set of leaves form which stops any long extension growths developing keeping the crown compact in form.
I think Trident maples look good in all seasons, when they have good ramification their winter image is superb, the array of autumn colours of the leaves is excellent and the spring flush and summer leaves are vibrant so a good bonsai tree for all seasons.