PlantFiles: Swamp Sunflower, Narrow-Leaved Sunflower
Helianthus angustifolius

I started with 4 plants given to me by a neighbor 4 years ago and I now have hundreds of stalks of the swamp sunflower. I love them when they're blooming and the bees and birds are stopping by, but man, are they invasive! I do absolutely nothing by the way of caring for them: no extra watering, fertalizing them, nothing except cutting them down in the winter and trying to get rid of the ones that have spread into the yard. And that doesn't work very well. They get the full morning sun, are in open yard, and have lived through drought and super rains. Until I got this month's Southern Living I had no idea even of the name. Found this site and have read all comments, etc. I'd like to know if anyone has them under the eaves of the house where they'd get practically not water. I'm a lazy gardener and like things that bloom, smell, and take minumium care. Any suggestions, anyone?

This is a nice late season bloomer that brings color to the fall. My Mother has a single plant that is taller than the eves of her house and is in full bloom this year (2009) in the middle of October. It is facing the south sun and came up voluntarily a couple of years ago. I am posting a picture of it.
Thanks, Barbara

I know this plant only as a blaze of early autumn color along I-75 in Sarasota County, Florida. It is so spectacular. Today, I finally pulled off the road and photographed it. If anything, it's prettier up close than from the middle lane. It's quite rangy in the wild but I have seen nursery catalogs that offer a dwarf cultivar [apparently developed in New Zealand] with very dense, compact growth behavior, but also with the same relatively short 2-month blooming season.

From the posted Zip Codes I appear to be the farthest North reporting on this plant.
I've had it for at least 6 years so it's hardy to at least -15F.
While may be a bog plant it is also very happy here w/ just regular soil, partial sun and natural watering.
I top-dress w/ manure every Spring and forget about it.

Ours gets about 6-7' tall w/ a spread of about 2 1/2'.
It starts blooming in Late Aug/early Sept and is at it's peak right about the first day of Fall.

I planted this against the foundation of the house. Most of the year this plant is a rosette of leaves. In mid- summer it sends up a bloom spike, which can be pruned back until about the end of August or early September to reduce its height. I have not ever trimmed mine. The canes of this plant have grown to about 10-12 feet high in my yard and are blown over fairly easily in the wind. One advantage of this is that the plant produces more blooms along the stems. The yellow blooms are quite showy when planted in mass. The blooms will draw some bees and butterflies, but the bigger draw is the birds who perch on the stems and feed on the relatively large seeds as they ripen. Yellow-throated vireos got a lot of my seeds this year (2002).

This plant is a member of the huge plant family, the Asteraceae (formerly called Compositae). Included in this group are all of the plants that are referred to as "Daisies", and "Sunflowers", among others. This plant can be grown in moist soil and in shallow, slow moving water that is no more than a few inches deep. It will also adapt well to dry roadside areas.

It does get tall with plenty of water but is limited in height in dry areas. One way to control its height and to increase the bloom is to pinch it back as it grows. Stop pruning it when it begins to produce flower buds. In the South it begins to bloom in September or October and continues into December. When it is done blooming, cut it back fairly short. Clumps of plants grow back in the following season. Propagation is by rootstock division.

SOILS: Fairly adaptable. Grows most vigorously in moist soils, but does fine in average garden soils. Drier soils will help keep the plant smaller and more contained.

HEIGHT: From 4 to 8 feet, depending on soils.