Cup plant is a native prairie perennial with a big presence in the landscape. It grows up to 9 feet tall and is topped with yellow, daisy-like flowers for weeks in summer. Cup plant (Silphium perfoliatum) received its common name from the way its leaves wrap around the stems to form tiny reservoirs—or cups—that hold rainwater. Songbirds are attracted to the water and feast on cup plant seeds. Bumblebees and honeybees use parts of the plant for nesting, and several pollinators visit cup plants for pollen and nectar. 

Where to Plant Cup Plant

Cup plant is at home in a prairie garden or meadow planting with rich, well-drained soil. Plant it alongside other North American prairie plants, such as little bluestem, big bluestem, coneflower, and monarda, to create an ever-changing wildlife oasis.

Space is an important consideration. Count on this long-lived perennial to grow 6 to 9 feet tall and 1 to 3 feet wide. It has a substantial presence in the garden and is best planted at the back of a landscape border, where it provides a bold structure. Cup plant is also an excellent addition to a naturalized or low-maintenance landscape area.

Cup plant spreads quickly by seed. In manicured garden settings, be prepared to pull out unwanted seedling. In prairie gardens and meadows, seedlings are often welcome.

How and When to Plant Cup Plant

Fall is the best time to plant cup plant from seed. Scatter the seeds on a prepared bed and press them lightly into the soil. Cover the entire seed bed with a loose covering of straw, and water the bed. The seeds can also be sown in spring, but they require a two-month period of cold stratification before being sown. Mark the location so you'll be able to easily find the emerging seedlings.

Plant cup plant nursery starts in early spring at the same depth as they grew in the nursery pots. Space plants at least 1 foot apart.

Water new seedlings and transplants regularly during the first growing season to encourage strong root development. Spread a 2-inch-thick layer of mulch over the root zone to prevent soil moisture evaporation and keep weeds at bay. 

Cup Plant Care Tips

Cup plant is a low-maintenance plant that flourishes when its basic needs are met.

Light

Cup plant grows best in full sun—at least 8 hours of direct sunlight a day. Native to North American prairies, cup plant thrives in planting spots with all-day sunlight. It tolerates a few hours of shade and is known to grow at the prairie edge, near woodlands, in its native habitat. 

Soil and Water

Cup plant tolerates both dry soil and clay, but it grows best in well-drained soil that is rich in nutrients. Crumbly, dark brown loam is perfect for growing cup plants, but this tough perennial survives, and even thrives, in many types of soil.  The plant adapts to a wide soil pH range from acidic to alkaline (4.5 to 7.5).

Temperature and Humidity

Heat and humidity don’t bother cup plant. This prairie plant thrives in high humidity and temperatures up to 100°F. It tolerates temperatures as low as 15°F in winter. As an herbaceous perennial, it dies back to ground level in late fall, but the dormant roots send up new shoots after a mild or harsh winter. 

Fertilizer

Cup plant doesn‘t need fertilizer. Boost the nutrients in the plant’s root zone and improve soil structure by spreading a 2-inch-thick layer of compost around the plant annually in spring. The compost will break down and move into the soil profile, adding nutrients and improving texture. 

Pruning

This perennial requires no pruning. If desired, reseeding can be limited by snipping off spent flower blossoms as soon as they fade. Removing the flower blossoms eliminates the potential for the plant to produce seed. 

Pests and Problems

Cup plant has no notable pests, but it reseeds aggressively unless it is deadheaded. Seedlings are usually easy to pull out of the ground when they are young. Established plants have an extensive, fibrous root system and are more challenging to eradicate. Remove unwanted seedlings as soon as possible. 

How to Propagate Cup Plant

The easiest way to multiply cup plant is to transplant seedlings from the original plant. Dig up young seedlings as soon as you notice them, and transplant the seedlings to a desired location. Water the transplants regularly for a few weeks to encourage them to develop robust root systems.

You can also multiply cup plant by collecting seed after it matures in late summer. Store the seeds in a dry, cool location. Plant them in the fall or refrigerate the seeds for two months of cold stratification and sow the seeds in the garden in early spring. Press the seeds a scant ¼ inch into the soil and water gently. Seedlings emerge within a few weeks.

Types of Cup Plant

The species, Silphium perfoliatum is the widely available cup flower; it is native to the central and southern U.S. states. The only known variety is Silphium perfoliatum var. connatum, which has hairy stems. It is relatively rare and found only in the mountains and the Piedmont of Virginia, West Virginia, and North Carolina.

Cup Plant Companion Plants

Mix cup plants with other prairie natives to create a rich tapestry of color and texture that beckons wildlife.

Little Bluestem

Little bluestem (Schizachyrium scoparium) is an easy-care ornamental grass that‘s beautiful in the fall when its blue-green leaves turn from rust to wine red. Birds, insects, and small animals use little bluestem for food and shelter. Clumps grow only 1–2 feet high, but flowering stems reach 5 feet. Zones 3–9

Big Bluestem

Big bluestem (Andropogon gerardii) is a warm-season grass, and most of its growth occurs during the warm summer months. However, this grass displays an attractive fall color and stands tall—up to 8 feet—through winter with its seed heads moving in the wind. Zones 4-9

Coneflowers

Coneflowers are native perennials that produce large blooms from summer to fall. Purple coneflower (Echinacea purpurea) blooms have a brown center with pinkish-purple petals, but other types are available in orange, yellow, and red shades. Most varieties grow to 4 feet tall. Zones 3–9

Joe-Pye Weed

Joe-Pye weed (Eutrochium purpureum) is a native wildflower with deep green foliage and airy purple blooms that add texture to a garden or act as a backdrop for smaller plants. It blooms in late summer and is popular with butterflies and other pollinators. It grows to 8 feet tall and wide. Zones 3-10

Goldenrod

Goldenrod (Solidago spp.) displays its yellow blossoms beginning in late summer and continuing into fall. Some varieties feature large flower clusters at the tops of tall stems; others boast gracefully arching stems holding single rows of blossoms. It grows to 3 feet tall and wide. Zones 4-8