Well you could just cut them in half , or so and that should encourage some branching. Some plants develop branches faster than others.

Mark

Usually, pruning will help to shape a plant so that you have multiple lateral branches to form a balanced plant.
Does this plant sit in a window all summer and in one position?
The branches all tend to grow off to the right in the photo attached.
I would not do any pruning until you see the plant come into active growth (not just the beginning signs of leafing).
With the plant of left in photo (looks to be a grafted form). You could prune it just below the long skinny branch of to the right side to encourage it to push out a few branches to give you nice base structure for later on.
You want to stay well above the scar of graft. The small little branch on the right just above graft scar may grow more, but sometimes they remain small.
Your other plant does not have a noticeable graft scar, so you should be able to prune where you like.
After pruning it is best to seal for preventative measures.
Laura uses a waterproof white wood glue and she has done alot of pruning as has Mary.

It might be worth rotating your pots every couple of days to give light all around. Not sure if it is just the way the pots have been placed, which gives the appearance of them growing toward the light source and this would continue if pruned and left in a similar site.
Rick

Rick,

They're placed right next to the window when it's not freezing near it. I admit, I don't turn them. That's something I'll start doing when they're back on the windowsill. The left one is a grafted plant, while the one on right is not (good eye!).

I'm worried about the large brown "wound" my grafted plant has (picture below). I think it was the result of a pruning before I had it. When it's time to prune, can I cut the brown part off as well? Will the wood glue help the coloring?

Also, I have not yet started fertilizing. I don't really know what, when or how much to feed it. Any advice on that?

Josette

Josette,
The brown circular end of the stem, is the old pruning scar. You have had it for a year now and it does not appear to be soft.
When it is in active growth. I would prune below the long branch at the top
to see if you can get it to produce two new branches to form a good framework.
You want to prune just below where the top branch is attached on a slight angle up toward the old pruning scar.
If using pruners have the blade side down toward the base and the anvil part (fat "U" shaped part) at top.
Best to paint on some glue or pruning sealer to cut surface.

For fertilizer, you want to wait until it has new growth starting and only at half strength. When in full growth, then by recommend ended rate.
I have started using the Dyna Grow Plant Pro 9-3-6 (I found at Hydroponic store). recommended by many of this group.
Rick