Not in enough sun?

Most likely, you're pampering them. Stop. You will get less flopping with less fertilization and water.

Ditto above. Grow 'em "lean and mean".

mine are only about 2 to 2.5 feet tall or so.. no water.. no fert.. abject neglect ...

hyper-fertilization is the scourge of homeowner gardening.. IMHO ...

in all but the very worst soils.. most plants need NOTHING FROM YOU ....

ken

I agree that over-fertilization can lead to lanky growth and that Black eyed Susans don't need fertilizer.

However I've grown Rudbeckia hirta 'Indian Summer' and 'Irish eyes' and they've both gotten floppy, even in fairly lean well-drained soil and without fertilizer. This year I decided to try pinching them to make them bushier and see if that prevented flopping. So far so good and some are just starting to bloom. I did the same with some Echinacea 'Summer Sky' which always flops (it's probably not growing in enough sun). We'll see how that does.

So if I quit over fertilizing and over watering will my black eye susan stand back up!

When I had the straight species they flopped ridiculously. I switched over to ‘Golsturm’ which stands quite upright in my garden.