House Plants: Advice, Pics, Sell and Trade

This is how the avocado looks at the moment. It’s about one and a half years old. All the leaves and half the height has grown this summer.

I don’t want it to become too big next year.
Do I prune? Or root prune? What to remove? Do I do it now when it’s dormant or right before the growing period next year?

Looks like a healthy avocado plant!

The thing is though that these are not made for being indoor plants.
Maybe you have seen older avocado plants at people's homes; presumably they are long-ish things that lean on walls or that need to be supported in some way.

Avocado will keep growing vertically in search for more light.
The only thing that will stop this is a lot of light (UV to be precise).
I tried getting them to grow more like a bush (I pruned them and gave them as much sun as possible) and this works to some extend, but not really, not in central Europe.

tl;dr - it's silly to grow avocados indoors.
prune it, to stop the vertical growing a bit, if you're lucky it will split in two, - and you can give it a bigger pot now (bury the lower part of the stem when doing this) so it will focus on building roots more instead of leggy growing during the winter.