Portraying large leaves with a rhubarb-like appearance, Prairie Dock is a statement native that will flaunt it’s blooms through October. This beautiful fall-blooming perennial will give life to an otherwise fading garden during the chilly months of September and October. Once established, Prairie Dock will be a maintenance-free tall accent to add as a backdrop or focal point to a native wildflower garden, prairie or roadside.
Wisconsin Native: Yes
USDA Hardiness Zone: to zone 2
Mature Height: 3-12ft
Mature Spread: 3ft
Growth Rate: Perennial
Growth Form: Upright, tall clumping perennial
Light Requirements: Full Sun
Site Requirements: Moist loamy soil; may tolerate slightly dry conditions
Flower: Bright yellow, 2-2.5″ across originating off a 6″ petiole
Bloom Period: August-October
Foliage: Dark-green basal leaves; 18″ long by 12″ wide
Fall Color: Not significant
Urban Approved: No
Fruit Notes: Lightweight, flat, hairless achenes carried by wind
Waukesha County, WI
Site Silphium terebinthinaceum in a moist location with a deep loamy soil. Prairie Dock is able to withstand drought and slightly dry conditions which makes rocky or tough sites suitable. The 12’ taproot makes it slightly more adaptable to drier climates. If the soil below the surface can stay moist, the taproot will be able to gather up the nutrients and survive the drought-conditions.
Prairie Dock works well as a backdrop in perennial gardens. The large dandelion-like, yellow blooms are prolific well into the fall seasons. Silphium terebinthinaceum does well along roadsides, within grasses and in many other prairie settings. Full sun is required in the planting location, once established this plant will take care of itself and be a staple of the garden, prairie or any suitable location!
Prairie Dock is a wonderful source of nectar for pollinators going into the dormant season. Long-tongued bees, such as honeybees, bumble bees and miner bees rely on Prairie Dock, the flower can also attract other species of wildlife. Hummingbirds and bee flies will be frequent visitors. The larvae of some beetles can burrow into the stem, causing no harm to the plant. Many other Wisconsin native insects will feed on the leaves and flowers, and while this may cause an unsightly appearance, this is beneficial to our native ecosystem; Prairie Dock will sustain through the damages.
Once established, Prairie Dock requires minimal care. The long taproot makes watering less of an issue than other fibrous-rooted species. During periods of drought, watering every couple of days will help keep the plant healthy. It may take Prairie Dock two or three years to flower; this should not be alarming, it’s expected for this plant in early youth.
Prairie Dock is a long-lived plant, the long taproot makes the species strong against pests and conditions. Certain years the plant will endure some insect setbacks; however, this will not affect the longevity of the plant.
The long petiole (sometimes 6” long) may cause the plant to become top-heavy and fall over in strong winds or when the plant is in full bloom.
Brown leaves or patches of brown can be a sign that the plant is enduring a drought or another environmental element (wind, climate, animals, etc.).
The Silphion genus comes from the American resin bearing plant, that has been used as a chewing gum throughout the early centuries. The species name terebinthinaceum is another name for turpentine, which is also in reference to the aromatic stem resins.
Native grasses are a perfect companion to pair with Prairie Dock. Native Big Blue Stem (Andropogon geradii), Little Blue Stem (Schizachyrium scoparium) and Bottlebrush Grass (Elymus hysrtix) will be great accents to show-off alongside Prairie Dock. Other native perennials from the Silphium genus, Ascelpias genus and plants like Meadow Rue (Thalictrum dasycarpum) and Ironweed (Vernonia fasciculata) work as accompanying tall accents.