Introduction to Cup Plant
Cup plant (Silphium perfoliatum) is a striking native prairie perennial known for its impressive size and beautiful yellow daisy-like flowers. Reaching up to 9 feet tall, it can become a showstopper in any garden. Its leaves wrap around the stem to form unique “cups” that hold rainwater, attracting songbirds and other wildlife. Bees, including bumblebees and honeybees, also visit this plant for its nectar, and its seeds are a food source for birds. With its ability to thrive in various environments, the cup plant is a must-have for creating a vibrant wildlife habitat.
Where to Plant Cup Plant
Cup plant is ideally suited for prairie gardens or meadow plantings where it can receive plenty of sunlight and ample space to grow. It thrives in rich, well-drained soil, making it perfect for areas alongside other native North American plants like little bluestem, big bluestem, cone flowers, and monarda. This combination creates a dynamic and ever-changing ecosystem.
Given its size, cup plant should be positioned at the back of garden borders. It grows between 6 to 9 feet tall and spreads between 1 to 3 feet wide, making it a bold presence in any landscape. Additionally, it is an excellent option for naturalized or low-maintenance garden areas. Be mindful that it can spread quickly by seed, so occasional management of seedlings might be needed in more structured garden designs.
Planting Cup Plant: When and How
The best time to plant cup plants from seed is in the fall. To do so, scatter the seeds over a prepared bed and gently press them into the soil. Cover the bed lightly with straw and water it well. While spring sowing is also possible, it requires a period of cold stratification (about two months) before sowing the seeds. Mark the area where the seeds are planted to easily identify the emerging seedlings.
For those planting nursery starts, early spring is ideal. Plant them at the same depth as they were in their pots, spacing each plant about 1 foot apart. During the first growing season, be sure to water regularly to help establish a strong root system. A 2-inch layer of mulch around the base of the plant helps maintain soil moisture and control weeds.
Cup Plant Care Tips
Cup plant is relatively low-maintenance and easy to grow once its basic needs are met.
Light Requirements
Cup plant grows best in full sun, requiring at least 8 hours of direct sunlight each day. Native to North American prairies, it thrives in sunny locations but can tolerate some light shade as well. It is often found growing near the edges of woodlands in its natural habitat.
Soil and Water Needs
Cup plant is adaptable to various soil types, including dry, clay, and sandy soils. However, it performs best in well-drained, nutrient-rich soil, such as crumbly dark brown loam. It can tolerate a wide range of soil pH from acidic to slightly alkaline (4.5 to 7.5). Regular watering during the establishment phase is crucial, but cup plant is highly drought-tolerant once established.
Temperature and Humidity Tolerance
This plant thrives in hot, humid conditions and can tolerate high temperatures up to 100°F. It is also resilient to cold temperatures, surviving winter lows of around 15°F. As a herbaceous perennial, it dies back to the ground each fall but reemerges from its roots in spring, even after harsh winters.
Fertilizer Requirements
Cup plant doesn’t require fertilizer. However, to improve soil structure and add nutrients, a 2-inch layer of compost applied annually in spring is beneficial. The compost breaks down and enhances the soil’s nutrient content, helping to promote healthy plant growth.
Pruning and Maintenance
This perennial doesn’t require regular pruning. If desired, you can limit reseeding by deadheading, or removing spent flowers as they fade. This simple step prevents the plant from producing seeds and self-sowing aggressively. Removing spent flowers also maintains the plant’s appearance throughout the growing season.
Pests and Problems
Cup plant is largely pest-free. However, it is known to reseed aggressively if left unchecked. Seedlings can be easily removed when they are young, but mature plants have an extensive root system that can be difficult to eradicate. If you wish to prevent unwanted seedlings, it is important to address them promptly.
How to Propagate Cup Plant
The most straightforward way to propagate cup plant is by transplanting young seedlings. Once you notice seedlings sprouting, carefully dig them up and transplant them to a new location. Water the transplants for a few weeks to encourage strong root development.
Alternatively, you can collect seeds after they have matured in late summer. Store the seeds in a dry, cool location until you’re ready to plant. If planting in the spring, the seeds need a period of cold stratification (about two months). After the stratification period, sow the seeds by pressing them about ¼ inch into the soil and water gently. Seedlings typically emerge within a few weeks.
Types of Cup Plant
The most common variety of cup plant is Silphium perfoliatum, native to the central and southern U.S. states. There is also a rare variety, Silphium perfoliatum var. connatum, found in the Piedmont region of Virginia, West Virginia, and North Carolina. This variety has hairy stems and is less commonly found in cultivation.
Best Companion Plants for Cup Plant
Pairing cup plant with other prairie natives will create a visually stunning, wildlife-friendly garden. Here are a few great companion plants for cup plant:
Little Bluestem
Little bluestem (Schizachyrium scoparium) is a low-maintenance ornamental grass that adds beauty to the garden with its changing colors from rust to wine red in the fall. It provides food and shelter for birds and insects. Growing to a height of 1-2 feet, its flowering stems can reach up to 5 feet tall. It thrives in zones 3-9.
Big Bluestem
Big bluestem (Andropogon gerardii) is another prairie grass that grows up to 8 feet tall. This warm-season grass is known for its attractive fall color and seed heads that move gracefully in the wind. It grows in zones 4-9.
Coneflowers
Coneflowers (Echinacea spp.) are classic prairie perennials that produce large blooms from summer to fall. Purple coneflower (Echinacea purpurea) is the most common variety, but there are also orange, yellow, and red options available. Coneflowers grow to about 4 feet tall and are hardy in zones 3-9.
Joe-Pye Weed
Joe-Pye weed (Eutrochium purpureum) is a tall native wildflower that produces purple blooms and attracts pollinators like butterflies. It can grow up to 8 feet tall and wide and thrives in zones 3-10.
Goldenrod
Goldenrod (Solidago spp.) is known for its yellow flowers that bloom in late summer and fall. This plant grows 3 feet tall and wide and is perfect for zones 4-8.
Conclusion
The cup plant is a robust and versatile addition to any garden. Its ability to thrive in a variety of conditions, combined with its striking size and wildlife-friendly features, makes it an excellent choice for prairie gardens, meadows, and natural landscapes. Whether planting it from seed or nursery starts, cup plant requires minimal care and adds beauty and structure to any garden setting. With its bold presence, it’s sure to become a standout feature in your outdoor space.
