Pampas Grass (Cortaderia selloana)

The American Pampas Grass belongs to ornamental grasses that look great in your garden, flower pot, or as a xerophyte. It can fashion many gardens and balconies, thanks to its many colors and different growth heights. Caring for the Cortaderia Selloana is quite easy and it caters for an excellent use as an outside plant, but you have to nevertheless consider a few cultivation details, so that this multi annual grass grows without any faults

I. Appearance and Characteristics 

Cortaderia selloana is a species of flowering plant in the Poaceae family. It is referred to by the common name pampas grass, and is native to southern South America, including the Pampas region after which it is named.

Cortaderia is derived from the Argentine Spanish name ‘cortadera’, meaning ‘cutter’, in reference to its razor sharp leaf margins.

Selloana is named for Friedrich Sellow (1789–1831), a German botanist and naturalist from Potsdam who worked as a plant collector in Brazil. He studied the flora of South America, especially that of Brazil. The specific epithet selloana was given by Josef August and Julius Hermann Schultes in 1827.

It is invasive in much of North America, which is why it’s best for many growing pampas grass to do so in pots and raised beds.

This ornamental grass is a perennial evergreen year-round in every temperate zone. In those regions with cold winters, it loses its evergreen status. The green leaves of pampas grass are razor-sharp, and can easily slice – so watch out! In spring, lovely seed heads in the form of feathery plumes emerge from the grass clump. As the wind scatters seeds, they germinate, rooting deep into the earth.

Pampas grass is dioecious, and it’s difficult to tell which plants are male or female until the plumes emerge. Female flowers are much wider and flayed at the sides. Female pampas grass catches pollen from the more compact male flowers via wind and insects. Those who want to grow new plants should purchase separate plants that include both male and female flowers.

However, gardening both sexes of plants is not recommended in the temperate zone in North America because pampas grass is classed as an invasive species, and it’s listed as 1 of the 16 Invasive Species Sold at Garden Centers in one of our posts. The clumps form so densely in areas where it remains evergreen that native plants have trouble gaining or retaining an ecological foothold due to lack of space. When people plant pampas grass in a zone or space that doesn’t have cold winters, they risk the spread of thick stands up to 20 miles away.

Pampas grass is dioecious, and it’s difficult to tell which plants are male or female until the plumes emerge. Female flowers are much wider and flayed at the sides. Female pampas grass catches pollen from the more compact male flowers via wind and insects. Those who want to grow new plants should purchase separate plants that include both male and female flowers.

However, gardening both sexes of plants is not recommended in the temperate zone in North America because pampas grass is classed as an invasive species, and it’s listed as 1 of the 16 Invasive Species Sold at Garden Centers in one of our posts. The clumps form so densely in areas where it remains evergreen that native plants have trouble gaining or retaining an ecological foothold due to lack of space. When people plant pampas grass in a zone or space that doesn’t have cold winters, they risk the spread of thick stands up to 20 miles away.

II. How to Grow and Care

Sunlight

Pampas grass does best when planted in full sun, or at least six hours of direct sunlight a day. It will tolerate light shade for part of the day. Pampas grass will not thrive and flower in full shade and will be susceptible to fungal diseases.

Temperature and Humidity

Rugged pampas grass can take high temperatures and humidity and will survive winters (and summers) in USDA plant hardiness zones 7-10. This plant does not reliably survive winters in zone 6 and will need to be brought indoors during the cold season. Pampas grass is typically evergreen in the South, but can die back in a harsh winter.

Watering

Water pampas grass well until it is established, and after that, this drought-resistant plant should take care of itself. However, pampas grass needs more moisture when actively growing in order to look its best. Give it a good soak during extreme or prolonged drought.

Soil

Pampas grass is a tough and tolerant plant. This plant isn’t fussy about soil pH, so you can grow it in just about any average, well-drained, acidic, neutral, or alkaline soil. Pampas grass also tolerates salt spray, making it popular for planting along the coast. In very dry and sandy soil, mix in some compost to help retain moisture.

Pampas grass does not do well in soggy soil. Heavy clay soil should be amended to improve drainage. In wetter areas, plant pampas grass on a mound to help water drain away.

Fertilizing

Pampas grass doesn’t generally require fertilizer aside from compost to improve soil (and drainage). If you want to give your plant a strong start in its first year, fertilize in the spring, summer, and fall with an all-purpose, slow-release plant fertilizer.

Pruning

Pampas grass leaves are razor-sharp. Wear eye protection, gloves, and long sleeves and pants when pruning or working near pampas grass, and plant in an area away from where children and dogs play. A hard pruning to the ground in late winter helps keep the plant under control and will help encourage healthy growth for next season. Cut pampas grass to 12 inches or lower in late winter before new foliage appears.

Propagation

Propagating pampas grass is easily done by division. Divide your grass every few years for the best results. Always wear protective gloves and clothing when dividing pampas grass. Take these steps:

• Divide pampas grass in the early spring (as early as March) when you see new growth. Use a sharp shovel to divide through the plant and its dense, tough root system.
• Slowly dig around the separated clump until you can remove the clump from the ground. You may need to wrestle a bit with the clump if it’s large.
• Fill in the hole and transfer the divided plant to its own area. If planted near existing grasses, space 6 to 8 feet apart to allow sufficient room for growth. 

How to Grow from Seed

Pampas grass can easily be grown from seeds but results will be patchy and you will likely grow only male grass instead of the preferred female plumes. Harvest seeds in the late summer or early fall when you see seeds on the fluffy plumes. The seeds are dark brown, black, narrow, long, and pointy. You’ll find more seeds on female plumes than on male plumes. Once you harvest the seeds, follow these steps:

• Cover seeds lightly with well-draining, rich soil.
• Cover the pots with plastic bags or plastic domes. 
• Place the pots in an area with bright, indirect light. 
• Germination should occur in about three weeks. 
• When the seedlings are large enough to handle, repot them into larger pots. 
• When they begin to take on a bushy appearance, plant them outdoors after all threat of frost is gone. 

Potting and Repotting 

More compact varieties of pampas grass can be grown in a container, especially if you plan to bring it indoors over the winter. These plants need a lot of room to grow, which means you’ll want at least a 10-gallon container, or a pot that is at least 15 inches wide. The containers can grow quite heavy and should be located where they can be easily moved for winter. Choose a container with drainage holes and use a good potting mixture to fill in around the plant.

Repot your plant every two to three years to give it adequate space to grow. Remove the clump from the pot, divide it into two or three plants, then replant in fresh potting soil.

Overwintering

To overwinter a container, wait until the end of the growing season in fall. Move your container to a sheltered location that will stay cool but above freezing, like a garage. Reduce watering during the dormant season. You can also overwinter pampas grass in a greenhouse.

Pests and Diseases

Pampas grass has virtually no pest or disease issues. However, it may cause or experience other problems. Here are a few issues you may see or want to avoid, with this grass.

Highly Flammable

This plant is highly flammable, especially when the grass dries out or dies. Avoid planting pampas grass close to buildings, outdoor cooking areas, or open flames where it can become a fire hazard.3 Because of its vigorous self-seeding nature, it may be best to grow a sterile plant to reduce the risk of rampantly spreading pampas grass around your property.

Razor Sharp Blades

The edges of a pampas grass leaf blade can be quite sharp. Handle the blades with protective gloves and clothing when cutting or pruning pampas grass. Consider planting this grass away from high-traffic pathways or where young children play. The plumes, however, are soft to the touch.

Attracts Critters

Like all tall grasses, pampas grass also makes a good hiding spot or habitat for small critters, including snakes, especially if the grass is untrimmed and untamed. If there are no open sources of food or birdseed nearby, there shouldn’t be too much of a problem with anything slithering into your pampas grass.

Dead Center

If the grass is not cut down every year and the dried, dead matter is not cleaned out of the center of the pampas grass stand, the center may begin to rot. The old foliage that was left to decay will cause rot and it will be difficult to fill in or fix the hole in the stand. Rot will also occur if the plant’s tussock (crown) is allowed to grow too large and full without division.

III. Uses and Benefits 

Pampas grass is a great way to bring a different tone to the green-heavy palettes and flower-heavy backdrops of British gardens.

It’s a versatile plant, equally suited to use as a border to frame an area, a screen to fence off an area, an element to add vertical interest to a flower bed or as a stand-alone focal point to draw the eye in a certain direction in a design scheme.

IV. Harvesting and Storage

If you wish to use your pampas grass flowers for floral arrangements, harvest the pannicles as soon as the flowers have fully emerged, but before they mature and begin shedding. They can be used immediately or dried for later use. When using, spray the plumes with hairspray prior to setting them in place. This helps prevent shedding.