How can I have a stronger stem for my Flowering Maple plant (see photos)?

More light, less water, maybe. Do you fertilize it at all? The more light a plant gets the stronger it grows. A plant with insufficient light will tend to be taller and less stocky.

@Adirondackwannabe It’s in direct sunlight. Perhaps, one of those fertilizer sticks would help?

I’d hold off on the fertilizer. That will encourage more growth, which will make it weaker. How many hours a day of direct sunlight?

Best I can do :-/
Hope it helps out……
http://www.thegardenhelper.com/abutilon.html

Thanks, you two.

Pruning usually causes plants to branch out.

From About.com
Feeding: Abutilon can be heavy feeders, probably because they do so much blooming. This is especially true when they are grown in containers. Feeding every other week with a dilute, water soluble fertilizer will keep them blooming.

Pruning: Abutilon takes pruning well. Tip prune young plants, to spur new growth and get a fuller shape. If yours starts to become tall and gangly, snipping it back to a leaf joint will encourage it to send out new branches. Abutilon can also be pruned back hard in the spring, if you want to control its size.

@BarnacleBill very helpful. Thanks.