Miscanthus sinensis ‘Variegatus’ and ‘Zebrinus’ are garden cultivars of Miscanthus sinensis that have become extremely popular ornamentals worldwide, for good reasons. They form tall and broad grassy clumps of elegant ribbon-like leaves that arch outward with a fountain-like habit. Tall reed-like flowering stems carry the beautiful plumes of flowers, followed by lovely fluffy seeds to provide an airy distraction in the garden. Depending on where these perennials are grown, they can be evergreen, but are generally dormant in winter, especially in severely cold regions, but they will sprout again in spring with great vigour. 

The name Miscanthus was given to this genus of perennial grasses by the 19th century Swedish botanist Nils Johan Andersson. It comes from the Greek words 'miskos' which means "stem" or "stalk" and 'anthos', meaning "flowers" in reference to the seed heads having stalked spikelets.

Miscanthus sinensis Picture courtesy Matt Lavin from flickrMiscanthus sinensis, the ancestor or our garden cultivars, is commonly called “Chinese Silver Grass”, “Maiden Grass”, “Zebra Grass”, or “Eulalia” and is a member of the grass family, Poaceae. It is native to China, Japan, South Korea, and Taiwan where it thrives as an herbaceous perennial, growing anything from 80cm to 2m tall, forming dense, grassy clumps of foliage from an underground rhizome.

Each leaf is sparsely pubescent on both sides with sharp and slightly serrated (rough) margins. Blades are green to variegated, with whitish collars. The pale-pink to reddish flowers appear in terminal panicles, 10 to 35cm long, held on stalks that can reach 3m. It not only spreads via rhizomes, but also by windborne seeds produced in autumn. In winter the plant becomes dormant and new growth emerges by mid-spring, replacing the previous year’s dried leaves.

Miscanthus sinensis in its original species form became immensely popular in western gardens about a century ago because of the powerful structure and year-round interest it added to landscapes, and today there are over 100 known cultivars, including those used for biofuel and paper pulp. Sadly Miscanthus sinensis has become an invasive plant in many countries, and in the USA it is listed as invasive in 25 states, the District of Columbia, and Ontario.

Garden cultivars of Miscanthus like ‘Variegatus and ‘Zebrinus’, are considered to be sterile and therefore safe to plant in gardens. They are also the easiest varieties to find in garden centres in South Africa.

Silver Maiden Grass (Miscanthus sinensis ‘Variegatus’) is a popular antique variety that has been used in gardens since the 1900’s. It forms a beautiful clump over 1m tall and about 2m wide and its arching ribbon-shaped leaves have rich cream-colored stripes running along the length of the deep green foliage, giving this plant a white appearance from a distance.

This grass requires a very long, hot growing season to be able to produce flowers. When it does, the tassel-like plumes rise above the foliage in early autumn and open with strong red tints, and as the seeds mature, they become fluffy, and persist well into winter, providing good winter interest, and a great accent to the foliage which fades to a tan colour after the first winter frosts.

In warmer climates this plant can become quite weedy. 

Miscanthus sinensis ‘Zebrinus’ must be counted as one of the most spectacular and captivating garden plants with its long arching leaves and appealing stripes across their width,  giving them the look of dappled foliage in the sunlight. Once mature, the dense grassy foliage can reach spectacular heights up to 1.5m or more, with an equal spread, to produce a wonderful screen or specimen plant. The plant is deciduous, and the brand new spring leaves are a deep green, only showing more and more golden striping as the leaf matures. Its lovely fluffy autumn seeds contrast wonderfully with the late autumn foliage.

Depending on where you live, zebra grass can be an invasive plant, like many other alien plants that spread by means of underground rhizomes. It is considered an invasive species in parts of the U.S.A.  in National Parks in North Carolina, Tennessee, Washington D.C., and Virginia.

Miscanthus sinensis var. condensatus ‘Cabaret’ is a tall, clump-forming grass over 1m tall and about 2m wide, but it can reach nearly 2.5m high once mature. The dark green leaves are up to 32mm wide and have a broad central creamy-white stripe. In autumn the reed-like flowering stems produce coppery-pink flower-heads that turn cream and silver as they mature.

To test the theory that garden cultivars are sterile and not a threat, scientists at the Chicago Botanic Garden conducted invasive-species trials, which ran for four years from 2006 through 2010. Thirty four Miscanthus varieties were grown, each in their own separate trial beds, and many aspects of their growth was monitored, including their vigour, bloom period, and flower production. In a short time the scientists observed an increasing number of seedlings carpeting the trial plots and adjacent landscapes each spring, despite them being quarantined.

Inflorescences from each of the 34 plants were also X-rayed to see if embryos were present in the seeds, and to assess the quality and the quantity of viable seed. The results were surprising, and the number of viable seeds per plant varied widely, from as few as 497 in the variety called ‘Dixieland’ to a staggering 349,327 in ‘Kleine Silberspinne’.

The study revealed that seed production and viability varied significantly among cultivars. Only ‘Hinjo’ and ‘Silberpfeil’, ‘Cabaret’ (M. sinensis var. condensatus ‘Cabaret’), and giant miscanthus (M. × giganteus) produced no viable seed.

In South Africa the two most common maiden grasses grown ornamentally, ‘Variegatus’ and ‘Zebrinus’, were included in the tests and here are the results of the viability of each cultivar’s seed. ‘Little Zebra’ produced 2,704 viable seeds per plant, and ‘Variegatus’ 211 seeds per plant.

Scientists concluded that many cultivars touted as “sterile” were, in fact, not sterile. And because many of the less-fertile cultivars were late flowering varieties, this may indicate that they did not have a long enough growing season to complete seed production, so they advise gardeners to be cautious.  These trials demonstrate the importance of evaluating all cultivars for their invasive potential.

Miscanthus sinensis 'Variegatus' Picture courtesy Leonora (Ellie) Enking from flickrIn the Garden:

‘Variegatus’ and ‘Zebrinus’ are not listed as invasive in South Africa, but I urge gardeners to monitor these plants in their own gardens for invasiveness, and to remove them if they do show signs of bearing fertile seeds which the birds will spread far and wide. This is especially important if you live within, or in close proximity to green belts.

Miscanthus brings movement into the landscape, and their dramatic foliage and plumes makes them great accent plants and a pretty backdrop for a mixed border. They demand attention if planted in groups and are used as fillers for a tropical looking garden.

 ‘Variegatus’, ‘Zebrinus’ and ‘Cabaret’ are wonderful close to water features where their lovely wavy plumes take centre stage, or in grassland or meadow gardens; together with other ornamental grasses. They are also often used to bind the soil on banks, and their clumping habit lends itself to the creation of small informal screens or hedges. Their lovely form is striking enough, even when they are planted alone in a container.

The foliage of Miscanthus ‘Zebrinus’ and ‘Cabaret’ last long in a vase and is grown commercially for the cut flower trade.

South Africa boasts several beautiful indigenous grass species that are used by landscapers, so if you are concerned, please do some research online to find indigenous nurseries in your area. They will give you the right advice and alternatives suitable for your region. Some may not be quite as showy as the exotic species, but the peace of mind they bring with the knowledge that you are supporting our local wildlife and especially our indigenous birds, who not only rely on grasses as a food source, but also for nesting material, far outweighs the fact that they may not be considered as pretty, and the joy of attracting birds to the garden is the true reward of planting indigenous grasses.

Cultivation/Propagation:

Ideal conditions for miscanthus are moderately fertile, and moist but well-drained soil, in full sun. They will tolerate semi-shade but in too much shade they will lose their bright colours.

Although drought tolerant, in hot and dry summer regions they will need moderate watering to keep them looking at their best in the garden, and in the winter rainfall regions the plants will need to be protected from being excessively wet in winter. The plants do well in coastal gardens, but will not tolerate direct maritime exposure.

They are hardy to cold and frost and in cold regions they become completely dormant in winter, enabling them to tolerate very low temperatures. ‘Variegatus’ is known to tolerate temperatures as low as -12°C.

When planting these grasses, give them sufficient space to develop and remember that they take 5 years to reach maturity. Prepare the beds by adding lots of compost, especially in very poor soils, and fertilise with compost or good organic plant food annually in spring.

If you like the look of the dry feathery flowers for winter scenes, leave them until spring rather than cutting them out. The dead stalks also act as a bit of mulch to protect the root system from winter's chilling temperatures. If you prefer to cut the stalks early in winter, leave about 15cm sticking up, and only trimming them away in late winter or early spring. A much simpler approach is to wait until late winter or early spring and then shear the stalks right down to ground level.

Problems, Pests & Diseases:

No serious pests are normally seen on the plants but they may succumb to leaf damage from chewing insects, aphids and spider mites

In warm and humid regions Anthracnose may become a problem, and preventative spraying against fungal diseases may be necessary. Anthracnose is a term used to loosely describe a group of related fungal diseases that typically cause dark lesions on leaves. In severe cases it may also cause sunken lesions and cankers on twigs and stems.

Rust diseases occasionally infest the foliage but it often goes away on its own in drier weather.

Warning:

Miscanthus 'Zebrinus' has no toxic effects reported for people, dogs, cats, horses or livestock.