If you are a Midwestern gardener, you may be knee-deep in the many rudbeckias that are blooming right now, a not unpleasant experience. Black-eyed Susans (Rudbeckia hirta) have been blooming for some weeks already, but now brown-eyed Susans (Rudbeckia triloba) and sweet black-eyed Susans (Rudbeckia subtomentosa) are getting into the full swing of things. Not all rudbeckias are created equal, and the latter two species are my favorites. The garden center favorite Rudbeckia ‘Goldsturm’ always seems a bit stiff to me, so as popular as it is, it’s not on my list of favorites. For sheer cuteness, the brown-eyed Susans can’t be beat–they come in tall nosegays of chubby little flowers. Towards the end of the summer, they will get a bit withered and rusty, especially if there has been drought, but they can be yanked out. My all-time favorite rudbeckia is the sweet black-eyed Susan, which is tallish–about 3-1/2 to 4 ft. tall–graceful in habit, and has very clean foliage. Later in the summer the gracefulness might segue into floppiness, but that’s when I swoop in and pick gigantic bouquets of them, and then cut them back. Both of the species self-seed somewhat, and if you want total garden control, they are not for you. Between the two species, if I had to make a choice, I would opt for the sweet black-eyed Susan because of its very clean
foliage. Rudbeckias tend to be subject to molds, mildews, and leaf-spot diseases, but the sweet black-eyed Susan stays clean. For information about these diseases, the University of Illinois Extension Service has a website with info about the various diseases and their (chemical) control. Here’s the address: http://web.extension.illinois.edu. But that’s why I like the sweet black-eyed Susans–no chemical control is needed. Sometimes sweet black-eyed Susans are called sweet coneflowers. This arises from the time when coneflowers and rudbeckias were lumped together in the same genus. But now purple coneflowers have been lasooed into their own genus (Echinacea) and if something is in Rudbeckia it’s not a coneflower. Or something like that. (In the interest of science, and wondering why this plant is called “sweet,” I have just gone out and nibbled on a leaf–it tasted like an old rubber tire. Oh, well.)
Sometimes New England Asters and various goldenrods are recommended as companions to plant with black-eyed Susans. These can be terrible self-seeders, though, and here is a situation where I would go for hybrids, which are more well-behaved. In particular, some of the hybrid goldenrods are just gorgeous.