Why do large four o’clock plants keep falling forward

Question

Why do my large four o’clock plants keep falling forward to the ground? How do I help them stand up straight? The four o clocks have some heavy stalks and some thinner ones. They look all tangled up. They have bright pink flowers and large leaves. The stalks look as though they are too heavy to hold upright. I fed them, added garden soil and mulch. They are in a sunny spot and have returned many years. This year and last year they fell forward after standing up for several years.

Answer 1

To keep them from flopping over you can give them a good pruning by mid June.
Here is a link about their care requirements.

https://www.gardeningknowhow.com/ornamental/flowers/four-oclocks/four-oclock-plants.htm