It must be weather related if you have plenty of it in some years and little in other years.
Down here, every group of flowers makes multiple seed pods every year, so to keep it blooming, I cut them off while they're still small - the flowers are a favorite for nectar here.
Sherry

Do you start your seeds indoors? I am also from a "colder" climate. Last year was the first year we grew tropical and I started seeds inside mid march. I planted them outdoors in may. maybe, in colder summers, they start too late to reach full growth and grow seed pods? Just a thought...

hello
I keep several tropical MW plant indoors over the winter, they are blooming now, I will make cuttings in a few weeks and have lots of babies by the time they can be planted out.they seem to have a quicker start from cuttings.
hope this helps
michelle
ps I also have a tray of seeds I just planted in the greenhouse