I can't figure out why my plants are not producing seeds like they used to.
Certified GKH Gardening Expert
This can happen for a few reasons. It is likely that there is not enough potassium, and phosphorus in the soil. Giving fertilizers high in these two can help them produce again.
Here is a link on their care: https://www.gardeningknowhow.com/ornamental/flowers/four-oclocks/four-oclock-plants.htm