Divide large established plants of Black Eyed Susans every three or four years. As a competitive flower, Black Eyed Susans can take over surrounding plants and flowers if left untamed.
@Petronius , I grow them in what I call my meadow garden. You are right, they will take over everything if I let them. Even the lawn! I am planning on rehabbing that section of the garden this spring, and plan to drastically curb the rudbeckia. BTW, I have two kinds: one is the typical black-eyed Susan, the other is Rudbeckia Triloba. Are you familiar with it?
It is taller than the regular black eyed susan, blooms later, and the flowers are somewhat smaller, petals are rounder. I actually like it better. Here is a poor picture of it blooming alongside a blue lobelia. This was taken on September 5th, the beginning of fall here. Here is is in late August blooming at the back of the garden. It can get 4-5 feet tall. BTW, can you see why this part of the garden is on my agenda to rehab this spring?
@Cayuga Morning, I can see why you want to change the garden. I did look up Rudbeckia Triloba. Rudbeckia Triloba is Brown Eyed Susan. Its native range is Central-eastern United States. It grows in Zones 4 to 8. It blooms July to October.
