Usually they'll naturally branch (all mine do), but in this case it apparently decided to turn into a skyscraper. :-)

Nicking off the top should stop the growth skyward and tends to encourage branching. We're near the middling-end of the season, so I'd wait until next spring when dormancy breaks as growth is already slowing as days shorten (yours may or may not be depending on where you are, and if you're very far south where they're a long-season plant, you may be able to nick it now).

Make sure to wear gloves and, even so, wash your hands afterward. They're in the dogbane family and intensely toxic in larger amounts, and irritating in small ones.

Appreciate the help .. stay safe!

Susan

A plant that's only a year or two old, might be genetically programmed to grow mainstems first and then, push out some side branches. It's all genetics.

Before you trim the top to induce back budding....take a Google-look at "tower Adenium", both pictures and You-tube videos. You just might want to rethink topping your Adenium.

Another alternative......grow your tall Adenium to the height that suits your fancy and then, graft a new top onto the original tall stem, branches and all. Just cut the top off the original stem, and graft stem sections onto the original stem. Grafting by using super-glue, works. There are videos that explain how this super-glue grafting method is done.

You literally, can create the Adenium that you want, growing the flowers that you want, by super-gluing.

Explore the possibilities. BTW, you can even use super-glue to graft side branches onto your lanky Adenium, to fill it out.

Good luck.

Genetics. I have one that grew one tall stem and I left it. This year, it put out about seven lower branches all on its own ... I did nothing. I love the way it looks.

Cut back long, slender shoots to about similar length as different stems, utilizing a couple of sharp, clean pruners. Prune any branches that rub or cross different branches. Make the cuts simply over a leaf hub, or where the stem gets together with another stem. Along these lines, there is no unattractive stub.