Chasmanthium latifolium, oat-like grasses for elegant flower beds

Chasmanthium latifolium clump with fresh seed panicles

A grass with atypical flowers, Chasmanthium latifolium is a superb grassy perennial.

Chasmanthium latifolium key facts
Botanical nameChasmanthium latifolium
FamilyPoaceae
Type – Grass

Bearing – arched clump
Height – from 20 inches to over 4 feet (50 to 1.20 cm) upon blooming
Planting density – 3 to 4 plants per sq. yard (m²)

Exposure – sunny to partly sunny
Soil – any type
Flowering – end of the summer

Native to the woody clearings of North America, Chasmanthium latifolium is one of those grasses that is as happy in the shade as it is in full sun. Its summer seed panicles, similar to those of oats, will definitely make your garden feel homely and timeless.

Planting Chasmanthium latifolium

Green seed clusters for chasmanthium latifoliumEven though it can cope with any type of soil, Chasmanthium latifolium particularly loves soil that has lots of humus. Bonus points if it’s also well aerated and drains at least a little bit. To ensure proper growth of this grass, it’s best to follow these few steps before planting.

  1. Amend the soil with sand and organic matter (compost, manure or soil mix).
  2. With a spade, flip soil layers upside-down and to properly mix its different layers together. This also helps aerate the soil.
  3. Plant your Chasmanthium latifolium.

When growing it in pots, follow the same steps, but also include a drainage layer at the bottom of the pot, to help water drain away.

Caring for Chasmanthium latifolium

As is often the case with grasses, Chasmanthium requires nearly no care at all. Give it 5 minute’s worth of work cutting it back at the beginning of spring so that new shoots can form a beautiful mound before blooming.

Note: if your soil is very poor, add soil mix or compost in spring. Simply spread it on the surface and rake it in lightly. If your Chasmanthium latifolium is in a pot, you’ll have to repot it every 2 to 3 years, more or less.

Propagating Chasmanthium latifolium

Of course, its possible to sow the seeds, but the technique that will give you the most control over the end result is clump division:

  • Unearth the clump, trying to protect the roots.
  • Divide the clump with two back-to-back pitchforks, or with a spade if the clump is too compact. You can even try using a large-toothed saw, if you’re ok with blunting it a bit.
  • Remove leaves and dry, dead stems.
  • Plant each new half or portion where you wish.

Diseases and pests

Chasmanthium latifolium is not vulnerable to disease nor to pests.

Landscaping uses and companion plants

Landscaping uses for Chasmanthium latifoliumGrasses are most magnificent when paired with other grass species in great numbers in a large flower bed. Chasmanthium latifolium can thus be planted together with:

This will give you a fantastic grasses bed that you’ll find stunning as seasons come and go.

If you prefer to delve into something more original, try pairing your Chasmanthium latifolium with Liriope muscari, Schizostylis coccinea, Hemerocallis ‘Stafford’ and/or Crocosmia ‘Lucifer’.


Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
Sun shining on Northern Sea Oats tassels by Swallowtail Garden Seeds under © CC BY 2.0
Arching over by Aaron Carlson under © CC BY-SA 2.0
Indian woodoats by Katja Schulz under © CC BY 2.0