If I would like to acquire a good indoor tree to work with, is this the wrong time of year? Is it better to plant my own tree or to just buy one?
Note that indoor is a tricky term. All plants are outdoor plants. Just.. Some cannot deal with our climate, and need to be brought indoors for (part of) the year.
Good plants that dor well indoors and could be kept indoors are specimens of ficus.
I am currently growing 5 species of Fig and of one species 2 variaties, only one of which is hardy enough to survive our -20C winters. The rest is outdoors till late sept / early October.
The best species for bonsai I find are the tigerbark ficus (ficus retusa), which I am experimenting with (And was bought on purpose as a mallsai fig from a local bonsai nursery). The other species I am tryin to get to grow is the F. benjamina of which I have the regular and what I think is the ‘Little Lucy’ variety. The latter is much slower growing, with very small leaves.
You can take cuttings for ficus year round. Do not try to grow them from seed. It is nearly impossible to get seed fresh enough to germinate, and even then, failure rates are 99,9% With cuttings you get exactly the same characteristics as the motherplant, and your plant is as big as a seedling would be after over a year.
Another species might be Azaleas. As far as I know, Satsuki azalea can be kept indoors for most of the year too.
No need to wait for next year to purchase and or style a ficus either; As they are tropicals, you can work on them year round. They do have growing phases and rest phases, but these are less critical than by non-tropicals. Also, they are not clearly linked to seasons (But more to your watering and temperature as well as number of ohours of sunlight; So you may get mid-winter growth spurs, if the weather turns sunny; I have had 50cm/20inches extensions in 6 weeks in December when we had sunny weather once with lots of snow => very bright conditions.