The perennial sunflowers (genus Helianthus), that is. Most sunflowers grown in gardens are annuals, and they are beauties in a sunny spot. Perennial sunflowers are wildflowers of the prairies, or cultivars much closer to the wildflower species than their annual cousins.
The rap on perennial sunflowers is that they are far too aggressive for a garden setting. That hasn’t been my experience, but of course behavior varies widely depending on species and conditions. When I lived in Wisconsin I saw some truly out-of-control colonies of Helianthus tuberosus (the source of Jerusalem artichokes, by the way) in a couple of backyards.
I’ve had some very mixed experiences with three perennial sunflower species: Downy Sunflower (Helianthus mollis), Woodland Sunflower (Helianthus strumosus), and Western Sunflower (Helianthus occidentalus). H. mollis and H. occidentalus need sun and well-drained soil, H. strumosus will take some shade and tolerates more clay.
I planted Downy Sunflower three years ago in the raised bed that stretches along the driveway and walk to the front door. That first year it did not do well. There was lots of rain that year, and my H. mollis was shaded by plants that grew tall early in the season. The result was that it grew stems in an odd corkscrew pattern and flowered sparsely. I concluded early that this was a failed experiment and yanked the plants out of the bed (or so I thought).
Next year, no sign that I noticed of Downy Sunflower.
Then this year, I witnessed Downy Sunflower II: The Return of the King. There were two plants that popped up in Spring and then just kept growing straight and strong, one to about 6′ and the other to at least 10′. Yes, I did have to stake them to keep them upright. They are blooming now: 3″ yellow daisies with centers that start dark and gradually turn golden.
Perennial sunflowers are one of those plants that will regrow if even a small piece of root is left in the soil. I think H. mollis has benefited from a drier year and a different mix of plants around it. I like it for the multiple flowers, and for the fuzzy grey-green leaves that look almost like Lambs Ears. Plus, as I’ve written before, I like tall plants, and this one seems to whisper: “Remember the tall-grass prairie.”
I’ll have to watch Downy Sunflower’s future behavior before settling its longer term role in my garden.
I have a very different story with Western Sunflower (H. occidentalus). Western Sunflower is supposed to be the most garden-friendly wild sunflower. It grows only to 3′ or so and is much less aggressive. The foliage is mostly basal, and it flowers at the end of long, almost leafless stems.
My experience was that H. occidentalus is docile to the point of being unable to compete with other perennials. I planted several Western Sunflower, and within about three years they had all disappeared.
Finally, I grow Woodland Sunflower in my lightly shaded backyard. It is a tough and reliable plant, providing color in late summer. I never watered it in this year’s horrendous drought. It’s grown shorter and bloomed less profusely, but otherwise doesn’t seem all that bothered.
I’m sure many would say that there’s no point in bothering with perennial sunflowers, the annuals are more colorful and generally easy to grow. They have a point. But I am one of those people who like some wildness in the garden (within limits – not right next to the sidewalk), who grow native wildflowers because there is very little wild space left for them to thrive in, and because they evoke the long-vanished prairie.