Miscanthus

( mis - KAN - thus )

At-A-Glance Information

Also called Silver Grass, this genus of perennial grasses includes species that make showy additions to landscapes. These grasses need full sun to partial shade and moderate to regular water to perform well in the garden. They form clumps of foliage with flower spikes on tall stalks that look like tassles or plumes. Foliage can be solid or striped, depending on the species and variety grown. These grasses can be used for privacy screening, as dramatic focal points, in mass plantings, or for architectural interest. Their flower plumes are prized in floral design.

Miscanthus Species and Varietals

The genus Miscanthus is a member of the plant family Poaceae, and includes between 12 and 20 species. Plants in this genus are closely related to those in Saccharum (Sugarcane), Sorghum and Imperata (Cogon Grass). The best growing zones for Miscanthus vary depending on the species. For more information, see the descriptions below. To find your zone, click here: Zone Map.

Miscanthus x 'Giganteus' (Giant Silver Grass, Elephant Grass, Giant Miscanthus, Giant Chinese Silver Grass, Giant Eulalia, Mammoth Miscanthus)
This sterile hybrid is an impressive, upright grower to 10-14 feet tall and 8-10 feet wide. It has dark green arching, drooping leaves and grows well in USDA hardiness zones 4a-9b or Sunset growing zones 1-24. Flower plumes appear in late summer and fall, emerging tan and opening silver. This is a great choice for a summer screen or hedge, and can take seaside conditions. Provide with some protection from hot, sunny afternoons. Often mistakenly sold as Miscanthus floridulus.

Miscanthus sinensis (Eulalia, Japanese Silver Grass)
This species of Silver Grass grows well in zones 2-24 and is native to Japan, Korea and China. Blooms appear in late summer or early fall, and are held above foliage in clumps. They are great to use for cut arrangements. This species is considered highly invasive across the eastern and central United States (in 25 states). Cultivars are listed and described below:

'Adagio'
Dwarf form with silver-green foliage and pink plumes.

'Cabaret'
With yellow stripes on leaves.

'Morning Light'
With horizontal yellow stripes.

'Strictus'
With yellow-variegated foliage.

'Variegatus'
Foliage is striped with yellow.

Caring for Miscanthus

Space these grasses between 12 and 18 inches apart for best coverage and airflow as a dense groundcover or screening plant. They can be spaced 3 feet apart from each other and other plants if being used as an accent feature. Plant in an area that receives full sun; ideally, they should be getting between 6 and 8 hours of sun each day, but do appreciate some late afternoon shade when temperatures are at their peak. Ensure that soil is well-draining, rich in nutrients, and has a pH of between 5.5 to 7.5 (acidic to slightly acidic). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water new plantings regularly as they establish a strong root system in their new home. At maturity, these plants have low to moderate water needs. As a general rule of thumb, water whenever the top few inches of soil feels dry to the touch, and provide deep waterings during extended periods of dry weather.

Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. These plants are not heavy feeders, and this should be sufficient to provide the necessary nutrients for the active growing and flowering seasons. Prune in late winter or early springtime just before new growth begins to emerge, and then cut all foliage down to between 1 and 2 inches from the soil surface. Miscanthus are long-lived perennials, and can survive in the landscape for between 15 to 25 years. They will form colonies via underground rhizomes which can be dug up and divided, providing plants for the landscape indefinitely.

Caring for Miscanthus in Containers
Miscanthus can be used as a 'thriller' plant in container arrangements. Choose a container that is at least 1 to 5 gallons and between 18 and 24 inches wide. Ensure that the pot has adequate drainage holes on the bottom to allow for excess water to flow away from the root zone. Fill with a well-draining potting mix amended with organic material, and top with a layer of mulch to suppress weed growth, maintain consistent soil temperatures, and increase soil moisture retention. These grasses require consistently moist soil to thrive; as a general rule of thumb, water every day in the summer. During the rest of the year, water whenever the top inch of soil feels dry to the touch. Miscanthus grown in containers will need more frequent irrigation than those grown in the ground. Prune in late winter or early springtime just before new growth begins to emerge, and then cut all foliage down to between 1 and 2 inches from the soil surface. Every few years, check the bottom of the pot to ensure that the plant is not outgrowing its root space. If roots are growing through the drainage holes in the bottom of the container, it is a good indication that the plant needs to be potted up; choose a slightly larger container and repot. These plants will need to be divided every once in a while to maintain their health (and the health of plants around them). For instructions on how to divide Miscanthus grasses successfully, see the Propagation section below.

Propagation

Miscanthus, or Silver Grass, is best propagated through division of existing plants; for instructions on how to propagate Miscanthus plants, see the instructions below:

Propagating Miscanthus by Division
This type of propagation is relatively simple; you will need a clean shovel, mulch, fresh soil, compost and pots (only necessary if you will be saving divided plants for transporting elsewhere). Division is best done in very early spring, and needs to be done every few years regardless of whether you have the goal of propagating the plants for best performance. To propagate by division, follow these steps:

Using a shovel, dig up your existing plant. Start from the outside and work your way in to avoid damaging the roots. Once it is worked up out of the ground, lay it out. Remove any dirt or debris from the roots.
Start to tease apart the roots with your fingers. Once the roots are untangled, separate your plant into segments, ensuring that each one has at least one thick root rhizome section attached.
Prepare your pot(s) or new planting site(s) with amended, well-draining soil. You can either bring in new soil or simply amend your existing soil with compost to complete this task. Then, plant your divisions and water thoroughly.
Apply a thick layer of mulch over the new planting to protect it from cold weather as it acclimates to its new home.

Problems and Pests

Certain Miscanthus species are considered invasive in some regions; see the species descriptions above for more information. Check with local authorities before planting. Miscanthus grasses can be susceptible to developing issues with the following pests and diseases in the landscape: