Ornamental grasses are some of the most versatile and low-maintenance plants you can add to your garden, providing stunning color, texture, structure, and movement in the landscape. While grasses bring year-round beauty to any outdoor space, their dazzling flowers and seed heads are especially impactful as Summer transitions into Fall.
Ornamental grasses are one of the easiest plant groups to grow, and many are drought-tolerant and able to thrive with very little water or care once established. They’re also highly resilient, rarely effected by pests and diseases and most ornamental grass varieties are deer-resistant and rabbit-resistant.
Grasses fall into two main categories: herbaceous varieties that go dormant in the frost and die back to the ground in Winter and evergreen varieties that keep their strappy foliage year-round. Herbaceous grasses are wonderful for adding movement and a sense of seasonality and change to gardens, while evergreens bring steadfast color and texture to the landscape.
Each group of grasses has their unique advantages and deserve a place in every garden. Herbaceous grasses are particularly well-suited to modern meadows and Bohemian landscapes, and their seedheads make attractive cut flowers when brought indoors. To achieve a Modern garden aesthetic, repeated use of Herbaceous or Evergreen grasses is a sure-fire way to create a clean, yet intriguing, modern look. For information on how to design a garden with grasses, visit our blog “Designing With Ornamental Grasses“.
Here is our ultimate list of the best herbaceous and evergreen ornamental grasses for Pacific Northwest gardens, including options for a wide range of styles and growing conditions. Read on for expert tips on ornamental grass planting and maintenance to keep your landscape vibrant season after season.
Herbaceous Ornamental Grasses
Herbaceous grasses grow tall and quickly each season with graceful, arching forms that sway in the breeze. This group of grasses is beloved for their showy soft flowers and seed heads that add excitement and interest to the garden in Summer and Fall. In Winter, they go dormant and turn a straw color but remain upright, offering texture, movement, and food for birds until cut back in the new year.
Our 7 Favorite Herbaceous Grasses for PNW Gardens
1. Feather Reed Grass – Calamagrostis
Karl Foerster Feather Reed Grass is beloved for its vigorous, upright growth and sandy-toned seed heads that stand strong and reach above gracefully arching green foliage. Calamagrostis in general is useful in mass plantings and is an ideal fit for both Bohemian and Modern landscapes.
2. Fountain Grass – Pennisetum
Pennisetum is an incredibly charismatic genus of grasses that captivates gardeners with its furry, fuzzy bottlebrush flowers and the way the plants appear to “fountain” up from the ground. Within the Fountain Grasses, you’ll find foliage in tones of green and purple, and flowers that range from white to beige to pink, making them a must-grow in Bohemian and prairie-style gardens.
3. Japanese Forest Grass – Hakonechloa
Japanese Forest Grass is a phenomenal plant for shady gardens and classic Pacific Northwest or Asian-inspired landscapes. While most herbaceous grasses get thin and weak in the shade, the graceful, long blades of Hakonechloa only grow lovelier – especially bright yellow varieties like ‘Aureola’ and ‘All Gold’ that tend to burn in afternoon sun.
4. Maiden Grass – Miscanthus
Maiden Grasses are strong, impressive, and not afraid to take up space in the landscape with their tall upright growth and enchanting tassel-like flowers that give way to fluffy seed heads. Whether you choose incorporate the snazzy stripes of Miscanthus ‘Gold Bar’ or the more romantic look of ‘Morning Light’, these are plants that will grow quickly and easily in almost any garden.
5. Mexican Feather Grass – Nassella
Mexican Feather Grass has lovely, dusty green fine-textured blades that fall in relaxed ways and is a great plant for using in containers or near pathways. Suitable for use in full sun or even dappled shade, over time Nasella will gently reseed, making it a nice fit for Bohemian landscapes.
6. Northern Sea Oats – Chasmanthium
With thick blades and fascinating, charm-like seed heads that resemble flattened oats, Chasmanthium adds personality to containers and landscapes alike. The seed heads are particularly beautiful in cut flower arrangements, making Northern Sea Oats an excellent choice for amateur florists.
7. Switchgrass – Panicum
Switchgrasses are a joy in the garden, thanks to the beautiful variation in foliage colors available throughout the group. Leaves dazzle with red tips to blue and purple blades, and the flower and seed heads delight with their starry tassels that are dotted with little seeds along the ends.
More Herbaceous Grasses to grow in the Pacific Northwest:
- Big Bluestem – Andropogon
- Blue Grama Grass – Bouteloua gracilis
- Millet – Millium effusum
- Muhly Grass – Muhlenbergia
- Little Bluestem – Schizachyrium scoparium
- Japanese Blood Grass – Imperata cylindrica
- Pheasant Grass – Anemanthele
- Tufted Hair Grass – Deschampsia cespitosa
Our 7 Favorite Evergreen Grasses for PNW Gardens
1. Blue Fescue – Festuca glauca
Short tufts of powdery blue green blades have made Festuca glauca a garden standout for years. These evergreen plants are incredibly low-maintenance and reliable, providing an easy-going way to achieve foliage contrast and texture in a wide range of landscape styles.
2. Blue Oat Grass – Helictotrichon
Blue Oat Grass provides a slightly taller, slightly wilder look to landscapes than Blue Oat Grass does, making it a great plant to incorporate into Bohemian landscape styles. Weave Blue Oat Grass into naturalistic plantings and use next to boulders for a pop of evergreen interest.
3. Lilyturf – Liriope
While Liriope is not a true grass, it is an excellent plant for achieving a carpet of deep green, strappy grass-like texture in locations with protection from afternoon sun. The lilac purple flowers that appear in Spring add additional interest to this groundcover-style plant.
4. Mondo Grass – Ophiopogon
Mondo Grasses are a group of highly attractive grass-like plants that can be used in mass plantings or along walkways to achieve a clean, modern look to beds. Black Mondo Grass is a particular garden all-star, thanks to its rich black strappy leaves, while Dwarf Mondo Grass is the ultimate low-maintenance plant for using as a slow-growing groundcover in virtually any setting.
5. Rush – Juncus
Juncus are native to the Pacific Northwest and are thus incredibly well adapted to our wet clay soils and rainy Winters and Springs making them a great choice for bioswales and rain gardens. The arrow-like upright foliage in hues of blue-green makes standard Rushes incredibly attractive, and the curlicue blades of ‘Twister’ and ‘Unicorn’ are a quirky addition to beds or containers.
6. Sedge – Carex
Carex is a mind-boggling diverse genus of sedges, with varieties that tolerate baking sun and virtually no water, and other options that can enjoy shade and wetter soils. The foliage colorations available in Carex also rival any other group of grasses, with warm reds and caramels, cool blues, electric yellows, and many gorgeous, variegated options in between.
7. Sweet Flag – Acorus
Acorus is a go-to plant for wet, shadier locations if gardeners want a low-maintenance evergreen grass-like groundcover with bright yellow coloration. Though it thrives in shade, Sweet Flag will also happily grow in sunnier, drier spots and even containers.
More Evergreen Grasses to grow in the Pacific Northwest:
- Clumping Bamboo – Fargesia
- Fiber Optic Grass – Isonephs cernua
- Horsetail – Equisetum hyemale
- Pampas Grass – Cortaderia
- Pheasant Grass – Anemanthele lessoniana
- Red Hook Sedge – Uncinia rubra
Ornamental Grass Planting & Maintenance Tips
Soil Conditions for Ornamental Grasses
Ornamental grasses are adaptable to different types of soil, but most thrive in well-draining, moderately fertile soil with a slightly acidic to neutral pH (6.0–7.0). Most drought-tolerant varieties tend to be herbaceous and are native to prairies, so they grow best in sandy, well-drained soil. Moisture-loving types are typically evergreen and can handle richer, consistently moist soil. Amending heavy clay with compost or sand improves drainage and supports healthy growth, especially when growing herbaceous grasses.
Watering & Fertilizing Ornamental Grasses
Once established, ornamental grasses are generally drought-tolerant, but deep, occasional watering during dry spells will keep their foliage and roots strong so they continue to look their best. When young, provide regular water during Summer to support root growth and development.
Overfertilizing should be avoided, but a light application of balanced or slow-release fertilizer in Spring can also encourage healthy growth without producing weak, floppy foliage.
Pruning Ornamental Grasses
Herbaceous grasses should be kept standing during the dormant season in Winter to protect the crowns of the plants and provide food and shelter for wildlife. The best time to prune herbaceous grasses is in early February—this should be done by cutting all remaining foliage to the before new growth appears.
Thought they do not require regular pruning, evergreen grasses benefit from an occasional “combing” or light raking to remove dead leaves, which helps them stay fresh and tidy.
Dividing Ornamental Grasses
Ornamental grasses have two growth habits—clumping and running—with most horticultural varieties being clumping. Clumping grasses grow in tufts or mounds, slowly increasing in diameter over time. Every few years, clumps can be divided, ideally in late Fall, to rejuvenate growth and prevent thinning in the center. To divide ornamental grasses, dig the entire plant from the ground and split it into smaller pieces, discarding the portion in the center that is no longer producing new shoots.
NOTE: Our garden centers do not carry most running grasses due to their invasiveness, though some smaller varieties can be useful in dedicated beds or containers.
Not sure of which Ornamental Grass is best for your landscape? Our garden center staff can help recommend a great variety that will suit your aesthetic and meet your needs!