Slender mountain mint (Pycnanthemum tenuifolium 'Cat Springs')

Overview

Pycnanthemum tenuifolium ‘Cat Springs’, known commonly as Slender mountain mint, is a valuable addition for gardeners seeking tough, aromatic, and pollinator-friendly perennials. This cultivar stands out with its extremely narrow, almost needle-like leaves and profuse clusters of pure white flowers that last from mid to late summer. As a vigorous, rhizomatous perennial, Pycnanthemum tenuifolium ‘Cat Springs’ establishes quickly, providing reliable vertical structure in the landscape.

This versatile plant thrives in a range of conditions, from full sun to partial shade, and tolerates dry or average soils once established. Its low maintenance needs make it excellent for larger landscape applications where reduced upkeep is desired. Furthermore, when the foliage of the Slender mountain mint is crushed, it releases a strong, spicy peppermint aroma, characteristic of the mint family.

The large flower heads of this cultivar are highly attractive to beneficial insects, making Pycnanthemum tenuifolium ‘Cat Springs’ an ecological powerhouse in mixed plantings or meadows. Its ability to handle challenging soils, noted by its Texas origin namesake, confirms its hardiness throughout USDA Zones 4 through 8.

Fast Facts

• Plant Family: Lamiaceae
• Plant Type: Herbaceous perennial
• Hardiness Zones: USDA Zones 4-8
• Size at Maturity:
  • Height: 2-3 ft
  • Spread: 2-3 ft
• Bloom Time: July to September
• Bloom Description: White
• Sun Exposure: Full sun to part shade
• Water Needs: Dry to medium
• Maintenance Level: Low

How to Grow

Plant Pycnanthemum tenuifolium ‘Cat Springs’ in the early spring or fall for best establishment. Locate it where it receives at least partial sun, though full sun will encourage denser flowering. This plant is easily grown in average, dry to medium, well-drained soil. Good drainage is essential to prevent issues, even though this Slender mountain mint variety is quite adaptable.

Maintenance for this mountain mint is delightfully low. Water regularly until the plant is fully established, after which it tolerates dry conditions well, aligning with its low water needs. Fertilization is rarely necessary; over-fertilization can lead to floppier growth. Pruning is generally minimal, though you can trim back stems after the main bloom period to encourage a tidier appearance or control spread.

Be aware that Pycnanthemum tenuifolium ‘Cat Springs’ is a vigorous grower via rhizomes. If you wish to keep its spread contained, plant it where its roots can be occasionally managed, or utilize root barriers. This plant naturally fits into drier environments like roadsides or open fields, reflecting its wild heritage.

Landscape Uses

The suggested uses for Pycnanthemum tenuifolium ‘Cat Springs’ highlight its adaptability, including naturalizing areas and rain gardens. Its upright habit makes it an excellent choice for the back of a perennial border where it can provide late-season white contrast among darker foliage. In naturalized settings or meadows, its rhizomatous nature allows it to spread gently, creating drifts of fine-textured foliage and white blooms.

Consider using this versatile perennial as an interesting plant for the herb garden, appreciating the aromatic foliage. It also performs admirably in rock gardens or drier slopes resistant to erosion. Furthermore, its ability to tolerate dry soils means it can be effectively placed near ponds or streams where soil moisture fluctuates seasonally, or used in open wet thickets.

Because of its flower display and narrow leaves, Pycnanthemum tenuifolium ‘Cat Springs’ serves well as a vertical accent or as a structural plant in less formal designs. Pair it with plants that enjoy similar sun/water regimes but offer contrasting textures, such as Sedum or ornamental grasses.

Standout Features

Flower Qualities

• Showy
• Good Cut

Noteworthy Characteristics

Pycnanthemum tenuifolium, commonly called slender mountain mint, is a rhizomatous, herbaceous perennial typically found growing in dry, open, rocky woods, dry prairies and fields, along roadsides, along streams and in open wet thickets across much of the eastern United States. An erect, many-branched, herbaceous perennial that grows 2-3’ tall and features extremely narrow, almost needle-like leaves and profuse terminal clusters of small, white flowers which bloom in mid to late summer. The specific cultivar, ‘Cat Springs’, offers large clusters of pure white flowers that attract beneficial insects and narrow green leaves that smell like spicy peppermint.

Tolerances

• Drought
• Erosion
• Clay Soil
• Dry Soil
• Shallow-Rocky Soil

Potential Problems

This plant generally suffers from no serious insect or disease problems, making it a resilient choice for the low-maintenance garden. Due to its mint lineage and sturdy nature, pests rarely cause significant cosmetic or structural damage. Proper cultural care, especially ensuring good air circulation and avoiding overly wet conditions, further minimizes any minor risks.

Frequently Asked Questions

What hardiness zones is Slender mountain mint suitable for?

Pycnanthemum tenuifolium ‘Cat Springs’ is well-suited for cultivation across USDA Hardiness Zones 4 through 8.

How large does Slender mountain mint grow?

This herbaceous perennial typically reaches a height between 2 and 3 feet, with a corresponding spread of 2 to 3 feet.

When does Pycnanthemum tenuifolium ‘Cat Springs’ bloom?

The bloom time for this variety is from July through September, featuring profuse clusters of small white flowers.

What sun exposure does Pycnanthemum tenuifolium ‘Cat Springs’ need?

Slender mountain mint performs best when situated in full sun to part shade locations.

Conclusion

The resilience, attractive white summer flowers, and aromatic foliage make Pycnanthemum tenuifolium ‘Cat Springs’ a highly functional and beautiful perennial. Its low maintenance requirements and tolerance for difficult soils ensure success for gardeners across a wide climate range. Before planting, confirm your location falls within Zones 4-8 and ensure the soil offers reasonable drainage for this robust Slender mountain mint.

Companion Planting

Select companions that appreciate similar sun exposure and can tolerate the dry-to-medium moisture profile once established. Plants that thrive in prairies or dry meadows pair perfectly with Pycnanthemum tenuifolium ‘Cat Springs’. Consider using contrasting textures such as the fine foliage of switchgrass (Panicum virgatum) or the bold architectural shapes of coneflowers (Echinacea). For mid-season color alongside the white blooms of the Slender mountain mint, Asters that bloom late or Coreopsis work well aesthetically and culturally.

Wildlife Benefits

The primary landscape benefit beyond its hardiness is the exceptional draw Pycnanthemum tenuifolium ‘Cat Springs’ has for pollinators. The dense terminal clusters of flowers provide abundant nectar sources throughout the hot late summer season when other blooms may be fading. Bees, butterflies, and predatory wasps are frequent visitors to these blooms. Its status as a Missouri native plant also supports local insect populations, making it an excellent choice for ecologically focused garden designs.