Threadleaf coreopsis (Coreopsis verticillata 'Moonbeam')
Coreopsis verticillata 'Moonbeam', or Threadleaf coreopsis, offers airy texture and continuous creamy yellow blooms from June to August in sunny, dry spots.
Complete Plant Information
Overview
Coreopsis verticillata ‘Moonbeam’ is a highly valued herbaceous perennial, celebrated for its delicate, thread-like foliage that provides an airy texture unmatched by many other sun-loving perennials. This cultivar, known commonly as Threadleaf coreopsis, produces a profusion of creamy yellow, daisy-like flowers throughout the summer season. Its resilience and ability to thrive in challenging conditions make Coreopsis verticillata ‘Moonbeam’ an essential plant for low-maintenance garden designs.
This Tickseed selection is noted for its long blooming period, typically running from June to August, offering reliable color when many spring bloomers fade. Unlike some related species, ‘Moonbeam’ is a sterile cultivar, meaning clean-up is less burdened by excessive self-seeding. It maintains a tidy, bushy clump form, reaching about 2 feet tall and wide, providing excellent structure for borders and cottage gardens.
Gardeners prize Threadleaf coreopsis for its exceptional durability. It readily handles heat, humidity, and drought once established, thriving particularly well where soils are poor, sandy, or rocky, provided drainage is excellent. Integrating Coreopsis verticillata ‘Moonbeam’ into your landscape ensures reliable, low-effort summer color.
Fast Facts
- Plant Family: Asteraceae
- Plant Type: Herbaceous perennial
- Hardiness Zones: USDA Zones 3-9
- Size at Maturity:
- Height: 1.5-2 ft
- Spread: 1.5-2 ft
- Bloom Time: June to August
- Bloom Description: Creamy yellow
- Sun Exposure: Full sun
- Water Needs: Dry to medium
- Maintenance Level: Low
How to Grow
For best establishment, plant Threadleaf coreopsis during spring or fall in an area receiving full sun. The greatest success with Coreopsis verticillata ‘Moonbeam’ is achieved when soil drainage is superior; it absolutely requires well-drained conditions and tolerates poor, sandy, or rocky soils better than heavy clay. Amending heavy soil with grit or compost to improve structure is highly recommended before planting.
Watering should be thorough at planting, but once the plant is established, its preference for dry to medium moisture means it holds up extremely well during periods of drought. Fertilizing is generally unnecessary, as rich, moist soils can encourage this perennial to sprawl unattractively. Keep maintenance low by focusing instead on pruning management.
To maximize bloom time for your Coreopsis verticillata ‘Moonbeam’, employ prompt deadheading of spent flower stalks. While tedious for large drifts, this action encourages continuous flowering well into late summer. Alternatively, plants may be sheared back moderately in mid to late summer. This shearing prompts fresh growth and a secondary bloom flush later in the season, while also controlling any developing tendency toward legginess.
Landscape Uses
The airy, fine texture of Threadleaf coreopsis makes it an excellent softener for borders, bridging the gap between more substantial plants. Its tolerance for poor, dry soils means it excels in rock gardens or along sunny, difficult slopes where other perennials struggle. The suggested use of “Naturalize” perfectly describes its behavior; allow drifts of Coreopsis verticillata ‘Moonbeam’ to naturalize within native plant gardens or informal cottage plantings.
For a classic cottage garden look, pair this pale yellow bloomer with richer jewel tones such as deep purple Salvia or blue Catmint (Nepeta). In contemporary xeriscaping, it combines beautifully with spiky plants like Yucca or drought-tolerant ornamental grasses, where the finely divided foliage of the Threadleaf coreopsis offsets their boldness. Its compact size (1.5 to 2 feet) also makes it suitable for the middle or front of a deeply planted border where mid-summer structure is needed.
Standout Features
Flower Qualities
- Showy
Noteworthy Characteristics
Coreopsis verticillata, commonly called threadleaf coreopsis or whorled coreopsis, is a rhizomatous perennial which typically grows in dense, bushy clumps to 1-3’ tall. Features yellow, daisy-like flowers (1-2” diameter) with yellow untoothed rays and yellow center disks. ‘Moonbeam’ is somewhat more compact (to 2’ tall) and features pale yellow, daisy-like flowers (1-2” diameter) with untoothed rays and darker yellow center disks, earning it the 1992 Perennial Plant of the Year award.
Tolerances
- Deer
- Drought
- Dry Soil
- Shallow-Rocky Soil
Potential Problems
Threadleaf coreopsis generally boasts very few serious pest or disease issues, contributing significantly to its low maintenance profile. Slugs and snails might occasionally appear, especially when conditions are damp, requiring standard preventative treatments. The primary cultural issue arises from soil conditions; crown rot is a risk if the plant is situated in moist, poorly drained soils.
A tendency to sprawl or become unkempt can sometimes occur, particularly if the plant is growing in overly fertile or consistently moist garden spots. This sprawl is usually addressed proactively by shearing the plant back slightly in mid-summer, which encourages a denser, reblooming habit. Uncommon fungal issues like powdery mildew may show up late in the season, especially in humid climates.
Frequently Asked Questions
What hardiness zones is Threadleaf coreopsis suitable for?
Coreopsis verticillata ‘Moonbeam’ is reliably hardy across USDA Zones 3 through 9, offering great flexibility for gardeners across many climates.
How large does Coreopsis verticillata ‘Moonbeam’ grow?
This cultivar typically reaches a height between 1.5 and 2 feet, spreading to a similar width of 1.5 to 2 feet at maturity, forming a medium-sized clump.
What sun exposure does Threadleaf coreopsis need?
Coreopsis verticillata ‘Moonbeam’ requires full sun exposure to achieve its best flower production and maintain a compact shape.
When does Threadleaf coreopsis bloom?
The continuous blooming period for Coreopsis verticillata ‘Moonbeam’ is generally from June through August, producing copious amounts of creamy yellow flowers.
Conclusion
The combination of airy, fine texture and robust adaptability to heat and drought makes Coreopsis verticillata ‘Moonbeam’ an indispensable summer element. This Threadleaf coreopsis cultivar provides superior performance with minimal fuss, rewarding the gardener with months of soft color. Before planting, confirm your soil drains well, as excellent drainage is the key to years of healthy cultivation.
Companion Planting
When planning a border featuring Coreopsis verticillata ‘Moonbeam’, select companions that share its preference for full sun and dry-to-medium moisture regimes. Plants that offer contrasting textures, like the bold leaves of Lamb’s Ears (Stachys byzantina) or the vertical spikes of Russian Sage (Perovskia atriplicifolia), create dynamic visual interest against the fine foliage. Since ‘Moonbeam’ blooms heavily, pairing it with shorter, early-season bloomers that can fill in as the Coreopsis matures, or late-season bloomers, ensures continuous garden performance.
Wildlife Benefits
While this cultivar is sterile and less attractive to seed-eating birds than some species, the abundance of daisy-like flowers is a significant draw for pollinators throughout the summer. Bees and butterflies frequently visit the creamy yellow blooms of Threadleaf coreopsis when many other sources are slowing down during mid-summer heat waves. Planting Coreopsis verticillata ‘Moonbeam’ ensures a reliable nectar source is available when garden activity peaks.
