@LiquidSkin - your horticulture skills have improved nicely. The most recent photo of mulberries are much healthier looking than your initial photos. Nice. For the moment, or the winter, I would work on letting these get bigger and bushier.
Then late winter or spring you can do a cut back. A couple more cycles of grow out and cut back, and then it will be time to look for a trunk line to make these little "shrubs" look more tree like, if you want to go the bonsai route. If you just want them as indoor fruit trees, keeping them shrub style will give you more fruit yield.
At some point, Not now, but maybe a year or two from now. If you go "bonsai", they will need bonsai pots, as the bonsai pot serves as the base, analogous to a picture frame, to set the image of a "tree". Bonsai is not a literal miniature tree. Bonsai is an abstract representation of a tree, with the focus being to elicit the an emotional response from the viewer as if they are seeing a scene from nature. The response does not need to be raw emotion, it can be quite subtle. But the purpose of the pot is to set the "place", be it a meadow, mountain, field, or forest or just to lift out of the ordinary realm of the windowsill or bench the tree is being displayed on. So bonsai pots serve a purpose. They are matched to the style of the tree. So first comes shaping the tree, giving it a style. Then, later choosing the pot to compliment the style of the tree.
I saw one of the miniature roses in the photo, glad they are growing. In your reading look up the bonsai related term "Kusamono". This is a category or sub-category of bonsai where roses fit in very nicely. The English translation of Kusamono is often loosely translated as "accent plant", but this does not cover the full range of what Kusamono can be used for. There are many sub-categories of Kusamono. First is "Shita kusa" which is the literal accent plant. Shita-kusa is always displayed with a tree. The height of the Shita-kusa is always shorter than the top of the stand that the tree is displayed on. The shita-kusa is chosen to one or more of the following; time of year, location, or evoke a particular emotion. Most often for location shita-kusa will signal a meadow or a forest, by being an understory species. A miniature rose could indicate an open meadow or cottage setting, where there is sunlight, and it could indicate early summer in flower. In fruit with leaves in autumn color, it could indicate autumn.
The general term "Kusamono" literally means "grassy thing" more or less. In early bonsai traditions Kusamono were always a mixed planting of 3 or more species and at least one of the species was a grass and one blooming herb. Modern bonsai has pretty much discarded the "rules" to just vague suggestions. Larger plantings if paired with trees are often visually separated from the trees, either into foreground or background to create depth and or distance. Or they are displayed on their own.
There is also the category of Kusamono where the accent plant is the focal point of the display. This is called "Sanyasou". Here the planting, in your case the rose would be the focal point. For this category the focal point must be very well grown and have significant evidence of age and maturity. It has to have a "presence". Your roses are a decade away from this point. But they could get there.
There is an artist, Young Choe, who has a great website showing different styles of Kusamono.
www.kusamonochoe.com
