Silvergrass (Miscanthus) is a genus of perennial, woody, and clump-forming grasses that are hardy, long-lived, and low-maintenance. Many cultivars are popular for growing in landscapes ornamentally.
Depending on which cultivar you opt for, they can vary significantly in height and spread. They work well in the back of borders, as a focal point in your landscape, a privacy screen, or to complement brightly colored bedding plants. The mounds of arching grass resemble a fountain, and plumes of impressive feathery flowers are often seen in the late summer.
The seed heads continue to offer winter interest before the foliage turns into shades of brown in the fall and then dies back in the winter. The foliage is a lush green or sometimes has an attractive variegated pattern. The flowers are often a shade of purple-pink or silver, and this is where the common name comes from.
Plant your Miscanthus cultivar in spring, and with the right conditions, you should be rewarded with new, rapidly growing bamboo-like shoots annually for years to come. These grasses bring graceful movement and structure to various garden landscapes. However, before planting, be aware that their abundant seed heads are notoriously invasive (unless you opt for a less fertile cultivar) and can displace native grass species.
|Botanical Name||Miscanthus spp.|
|Plant Type||Deciduous Grass|
|Mature Size||2 to 12 ft. tall|
|Sun Exposure||Full Sun, Partial Shade|
|Bloom Time||Late Summer, Fall|
|Flower Color||Silver, Pink|
Miscanthus species have a spreading, rhizomatous root system. This needs adequate space and time to develop. For this reason, it's best to plant in early spring (March or April) when soils are moist and the root system has plenty of time to establish. This helps the grass to cope better with drought and frost conditions. With their cascading habit, they don't need staking and grow well in a variety of conditions.
A big advantage of miscanthus species is that they don't suffer from many diseases and are largely pest-free outside their native areas in Asia.
The most popular ornamental miscanthus species, Chinese silvergrass (Miscanthus sinesis), is reported as invasive in states including Connecticut, Washington D.C., Georgia, Illinois, Indiana, Kentucky, Maryland, North Carolina, New Jersey, Pennsylvania, South Carolina, Tennessee, and Virginia.
If you want to appreciate the beautiful, silvery plumes, a full sun position is best. They can tolerate light shade, but you might not see such an impressive flowering display.
The exceptions are miscanthus species with variegated foliage. Too much hot, direct sunlight can scorch the leaves.
Most Miscanthus species grow in a wide variety of soil conditions and pH levels; they just need to be well-drained. While they thrive in relatively rich, loamy, and moist soils, they're often the go-to ornamental grass types for heavy soils as they cope surprisingly well in them.
Miscanthus species are typically pretty drought-tolerant plants, so you won't need to water them often, if at all. In fact, overly wet soils are a problem and can cause plants to die over the winter. Generally, those species with narrow leaves are a little more drought-tolerant.
When there is an extended period without rainfall, a deep watering occasionally is best. It should just be enough to dampen the area around the rootball and not leave it soggy.
Temperature and Humidity
Silvergrass can withstand a wide variety of temperatures, but the plant produces its most impressive flowering display when summers are hot. Excessively cold soil temperatures can damage the plant's rhizomes, and it's a particular problem while establishing.
Just how much cold your miscanthus can handle will depend on the species and cultivar you select. Studies indicate temperatures below 26 degrees Fahrenheit kill off the hybrid species Miscanthus × giganteus (giant miscanthus) that's commonly grown agriculturally.
A big advantage of Miscanthus is that it rarely needs additional feeding, especially when mature. The extensive rhizomes store enough nutrients to see it through the growing season. In the first couple of years, while the grass is establishing, applying a spring layer of compost made from organic matter should be sufficient.
Types of Miscanthus
There are around 20 different Miscanthus species, but the most popular to be grown ornamentally is Chinese silvergrass (M. sinensis) and its many associated cultivars. Although it's known to be invasive, some cultivars don't self-seed readily. A few popular miscanthus options worth considering include:
- Zebra grass (Miscanthus sinensis 'Zebrinus'): Known for its stunning variegated foliage, height, and attractive plumes.
- Miscanthus sinensis 'Bandwith': This infertile cultivar is a compact variegated variety with attractive green and gold bands on the foliage.
- Porcupine grass (Miscanthus sinensis 'Strictus'): If you're looking for a tall, variegated ornamental grass to use as a focal point in your garden or at the back of your perennial border, this could be a good choice. It reaches up to eight feet in height and has an upright growth habit.
To tidy up clumps and promote healthy new growth, it's a good idea to cut back any dead leaves. This can be done in late winter but is best done in early spring when new growth starts appearing at the base of the clumps.
If you want to curtail your plant's invasive qualities, remove the seedheads in the early fall.
A common method of propagation is to divide the rhizomes. It's best to wait until the plants are fully established (at least two to three years old), and do it during the dormant period, ideally in the early spring.
Be aware that old growth can be tricky to divide, and you might need to use two forks to divide it through the crown. Employing the help of an additional family member or friend makes things easier.
How to Grow Miscanthus From Seed
Miscanthus can also be grown from seed. Germination is relatively fast, usually occurring within two weeks. They like relatively cool temperatures for germination—no warmer than 75 degrees Fahrenheit.
If you're opting to sow them directly into the ground in early spring, only do this in regions where the soil is cool but not frosty. If sowing indoors, you can transplant seedlings once there is a minimum of at least two sets of leaves.
Common Problems With Miscanthus
Miscanthus species are generally pretty hardy and low-maintenance, but certain issues can crop up depending on growing conditions and care.
If you experience a cool summer with little sun, you might not get the abundance of flowers you hoped for. This can also be a problem if you aren't selective about where you position your miscanthus. For example, don't plant it under a shade tree.
Brown Patches on Leaves
Excessive direct sun can result in scorch or rust along the leaf edges on Miscanthus. Cut out any rusty leaves you see straight away. To prevent this, select a partial shade spot with filtered light, but only for variegated varieties.
While Miscanthus is pretty drought-tolerant, an excessive period without water can result in the foliage rolling in on itself, and it will eventually die back from the tip. Occasional deep watering during extended dry spells helps to prevent this, but be careful not to water-log the root ball.
How long can Miscanthus live?
It isn't unusual for silvergrass to live for 15 to 20 years with the right care and conditions.
How fast does Miscanthus grow?
Fast-growing Miscanthus species usually reach their maximum height and spread within their first few years. Depending on the species and cultivar, their ultimate height varies from around two to 12 feet tall.
What are the alternatives to Miscanthus?
If you're looking for an alternative, easy-to-grow ornamental grass that's not known for having invasive qualities and is native to North America, you could try growing switchgrass (Panicum virgatum).
Chinese silvergrass (Miscanthus sinensis). Invasive Plant Atlas.
How Cold Weather Impacts Miscanthus. Iowa State University Extension.
Miscanthus sinensis. Missouri Botanical Garden.
Al Hassan, M., Investigating applied drought in Miscanthus sinensis; sensitivity, response mechanisms, and subsequent recovery. GCB Bioenergy, 14(7), 756-775. https://doi.org/10.1111/gcbb.12941