I first saw a climbing Black-Eyed-Susan (genus thunbergia) at The NY Botanical Garden. I had heard it is an easy vine to grow and is best started from seed. In fact, I wasn’t able to find it as a potted plant at any of my local garden centers, so I had no choice but to start it from seed. I decided it must be a sleeper because I couldn’t find the seeds at my garden centers either, and ended up ordering from Park Seeds online.
After starting the seeds indoors in my greenhouse in early spring, I waited until all threat of frost was past and planted 3 seedlings in a container on our deck with an obelisk style trellis for them to grow up. This plant has a twining habit, so it has tendrils that circle around vertical objects and get their support that way. In no time it was twining around the obelisk, with a little guidance from me. By August it was a 4′ high vine with pretty yellow/orange flowers with a black center, hence the name Black-Eyed-Susan.
This spring I wondered if the plant would self sow in the same container it grew in last season (since I mysteriously misplaced the seed packet I purchased last year). I waited and by July I was rewarded to find two new plants growing pretty vigorously and twining up the obelisk. They haven’t bloomed yet but they are growing fast and everything is late this season, so they’ll bloom soon.
Black-Eyed-Susan is a tender perennial and will survive outdoors in Zones 8 and above. Where I live in Zone 6 we treat it as an annual. But rather than bring it indoors this winter I’ll just let it self sow next year. It’s a smaller vine, usually maxing out at 4-6’ tall, so it’s perfect for a container or to grow up the side of a fence. It’s not a vine you would use for a privacy screen unless it is one of several plants growing together for that purpose.
The plant is available in a variety of flower colors, from yellow, to yellow/orange, to red, all with an inky dark center. My friend Ruth Clausen told me that it is now available in white also (thunbergia alata). That would be stunning, and maybe I’ll add that to the mix in my container next year.
My plants wilt if they get too much sun, so I move the container to a spot where it gets sun part of the day and dappled light the rest of the day. I’ve been watering it with manure tea we got from ranchers in Colorado who are preparing to sell it commercially to home gardeners. Our plants seem to be responding to the richness provided by the manure tea. They like rich, well drained soil.