Sweet Black-eyed Susan

Rudbeckia subtomentosa

Description & Overview

Sweet Black-eyed Susan delivers pollinator power while adding height and color to any garden. This classic native perennial is common along the Mississippi River and often found in moist open prairies and meadows. It thrives in full sun while other perennials in the garden begin to quell under the late-summer sun.

You may also know this Wisconsin native perennial as Sweet Coneflower.


Core Characteristics

Mature Height: 2-6 feet
Mature Spread: 2-3 Feet
Growth Rate: Fast
Growth Form: Upright Perennial
Light Requirements: Full Sun
Site Requirements: Moderate to wet, sandy or loamy soil
Flower: 1-4 inch wide golden yellow flowers on 8-inch long stalks
Bloom Period: July-October
Foliage: Dark green. Variation in size and shape along the length of the stem. Leaves 3-8 inches. Lower are lobed. Upper lack lobes.
Fall Color: N/A
Fruit Notes: 3/32” Black and elongated. Begin ripening in September.

Suggested Uses:

Sweet Black-eyed Susan is naturally found in rich soil or sandy prairies, as well as in the gravelly seeps and banks that were prominent throughout much of southern Wisconsin. Although they prefer moist soil, established plants are drought tolerant and withstand competition from other species rather well, making Sweet Black-eyed Susan a good option for restoration projects.

Rain Gardens: Love of moist soil makes this Rudbeckia a great choice for a rain garden, especially where height is needed as it can reach up to six feet.
Wildflower Garden: Sweet Black-eyed Susan adds color in late summer. Planting along the back of the garden to help cover unsightly fencing.

Restoration: Use this native perennial in areas that provide the same conditions as its natural habitat. Meadow seeps, wetter prairies, and streambanks would all be ideal sites. Add a showy pop of color alongside a drainage ditch in front of the house! Many Rudbeckia species are salt-tolerant, although there is not very much information on this species in that regard.

Wildlife Value:

The leaves, nectar, and seeds all provide nourishment for many birds and insects. Bees, wasps, and flies are heavy pollinators of Sweet Black-eyed Susan, including but not limited to, Carpenter bees, Cuckoo bees, digger bees, leaf-cutting bees, Halictid bees, dagger bees, Sphecid wasps, Vespid wasps, Syphid flies, and bee flies, who all feed on nectar.

Sweet Black-eyed Susan is the host plant for the larvae of several Lepidoptera species, namely, Gray-blotched Epiblema (Epiblema carolinana), Epiblema tripartitana, Common Pug (Eupithecia miserulata), Silvery Checkerspot (Chlosyne nycteis), and Wavy-lined Emerald (Synchlora aerata). While not the number one choice for monarchs, the long-lasting flowers of Sweet Black-eyed Susan bridge the bloom gap between earlier and later-flowering species, providing some nectar ahead of their long journey south.

Seed-eating birds such as American Goldfinches, Dark-eyed Juncos, and Black-capped Chickadees will nibble away at the nutritious seeds.

Mammalian herbivores tend to avoid R. tomentosa.

In short, this tall, drought-tolerant, happy-in-a-ditch native will give back to a large number of our smallest species.

Maintenance Tips:

Promote additional flowering by deadheading spent blooms.

Plants can be divided in early spring.

Pests/Problems:

Sweet Black-eyed Susan can become leggy, causing it to topple over. This can be avoided with proper siting and maintenance. Full sun and moist soil are preferred, as plants in shade, and wet, fertile soil are more likely to droop.

Proper air circulation will help prevent powdery mildew.

Rudbeckia subtomentosa seems to be less susceptible to Septoria leaf spot, a common problem with many Rudbeckia species.

Leaf Lore:

Name: The genus Rudbeckia is named after the Swedish botanist, Olof Rudbeck. The specific epithet subtomentosa pertains to the short, dense hairs on the underside of the leaves.

Sweet Black-eyed Susan lives for many years. Close relatives, Black-eyed Susan (Rudbeckia hirta) and Brown Black-eyed Susan (Rudbeckia triloba), are biennials – the first year of growth consists only of basal leaves, the following year they flower and end their life cycle.

Companion Plants:

Similar wetter-soils:

  • Sneezeweed (Helenium autumnale)
  • Pennsylvania Sedge (Carex pensylvanica)
  • Ironweed (Vernonia fasciculata)
  • Witherod Viburnum (Viburnum cassinoides)
  • Common Winterberry (Ilex verticillata)
  • Tuliptree (Liriodendron tulipifera)
  • Spiderwort (Tradescantia ohiensis)
  • Carolina Rose (Rosa Carolina)
  • Spotted Joe-Pye Weed (Eutrochium maculatum)

More great pollinator-friendly plants:




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