Mexican Feather Grass (Nassella tenuissima) is a popular, low-maintenance ornamental grass known for its fine texture and graceful movement. This perennial forms a cascading fountain of slender, hair-like leaves, adding airy elegance to gardens. Its soft, wispy foliage and feathery plumes create visual interest, swaying gently with the slightest breeze.
Planting and Site Selection
Mexican Feather Grass thrives in full sun exposure, which encourages vibrant growth and intensifies its silvery-green or lime-green hues. While adaptable to various soil conditions, it requires well-draining soil to prevent root rot. For heavy clay, amend the soil with sand and organic matter, such as compost, to improve drainage and provide essential nutrients. Plant specimens 20 to 24 inches apart to allow for their mature size and ensure good air circulation. When planting, place the crown level with the surrounding soil in a hole slightly larger than its root ball, then backfill and water thoroughly to help establish the roots.
Ongoing Care and Maintenance
Once established, Mexican Feather Grass is notably drought-tolerant, requiring minimal watering. Occasional deep watering during prolonged dry spells, especially in hot climates, can be beneficial, but it is sensitive to overwatering, which can lead to root issues. Allow the top few inches of soil to dry out between waterings.
Fertilization is generally not necessary, as the grass thrives in poor to moderately fertile soils. If the soil is extremely nutrient-poor, a light application of a balanced, slow-release fertilizer or compost in early spring can support growth, but over-fertilizing can cause floppy growth. This grass is relatively resistant to pests and diseases.
Pruning and Winter Preparation
Pruning Mexican Feather Grass is best done in late winter or early spring, before new growth emerges. This timing is crucial because it is a cool-season grass; cutting it back later can mix old brown growth with new green shoots. Cut the plant back to a few inches above the soil. This removes spent flower stalks and old foliage, promoting a compact shape and fresh spring growth.
Mexican Feather Grass is winter hardy in USDA zones 7 through 10, tolerating temperatures down to about 0 degrees Fahrenheit. In milder climates, it often remains attractive through winter. In colder zones (e.g., 2-6), it is typically treated as an annual.
Managing Common Issues and Spread
Mexican Feather Grass can sometimes exhibit browning or flopping, which may indicate insufficient water during hot spells or, more commonly, overwatering and poor drainage. Ensuring the soil drains well helps prevent these issues. Over-fertilization, particularly with nitrogen-rich products, can also cause the grass to fall flat.
This grass has a prolific self-seeding habit, which can lead to vigorous spread and potential weediness in some regions. In areas like California, it is listed as an invasive species. To manage its spread, deadhead spent flower stalks before seeds mature to reduce unwanted seedlings. Thinning volunteer seedlings when small or careful landscape placement can help control its naturalizing tendency.