Move over Rudbeckia fulgida! If you want abundant flowers, with a taller habit, well you've got to get some Rudbeckia triloba.
There is a love/hate relationship with this plant, but I am not sure why. It's done nothing but perform for me.
Rudbeckia triloba is a native plant to North America. Seen in a lot of fields or even roadsides in Central/Eastern United States. For me it's a welcomed performer in the perennial border - specifically in the tough areas where you need height and long blooming periods.
In this photo below, R. triloba is grown in the back. Nearly a foot taller than its relative: R. fulgida.
Rudbeckia triloba has smaller flowers than other Rudbeckias. I have a real fondness for their delicate petals. They are wonderful to dry - great for craft making.
Be aware: it is an herbaceous biennial, acting somewhat like a perennial. I've had limited success in keeping the same plant growing for about a year or two, then having to be reliant on seedlings for the following year. I've seen it reach about 5 feet in height, but here: it's around 3 1/2 feet tall.
Alos known as "Brown Eyed Susan", its flowers can nearly bloom for 3 months!
In my experience, it has better drought tolerance than R. fulgida, R. hirta and a little less tolerant than R. laciniata. Very few pests are attracted to R. triloba. Just some spider mites when it gets really hot in the summer and some leaf minor.
Here are the differences:
Rudbeckia triloba is a fabulous pollinator plant. Providing pollen and seeds for nature. Not to mention winter interest with their brown centres.
If you are growing R. triloba in a lot of shade, it stretches thus requiring some sort of support. An odd twig or peony ring would suffice.
Here is a sample of a small R. triloba seedling: easy to transplant in early spring to relocate. Similar looking to the fulgida baby plants, but less pubescent (less hairy).
A good helping of leaf mould or compost around the root level in spring-time, and it'll perform beautifully.
If you have concerns of it spreading uncontrollably, then remove the spent flowers (if left will naturalize the garden).
Note, when handling: wear long sleeve shirts when the plant is gaining height. I find I get an itchy arm (similar to Juniper itch) if I weed around the base. Thankfully, it grows quickly and once it reaches 2 feet in height, the growth will choke out any room for germinating weeds!