Blades of glory: Types of ornamental grasses

Story by Michael McCoy

Ornamental grasses bring unique beauty and movement to our landscapes, plus, they play a key role in increasing diversity. Here are a few varieties to try.

Tall grasses (1.8m+)

Golden oats (Celtica gigantea syn. Stipa gigantea)

One of the most beautiful ornamental grasses of all, with golden oat-like seed heads to 1.8m, at least a metre clear of its 80cm clumps of narrow evergreen foliage. It’s good for cool temperate climates in drier soils with good drainage. It’s best used as a single specimen within lower plantings.

Miscanthus transmorrisonensis
A semi-deciduous grass (fortunately, it can be treated as deciduous, allowing it to be cut to the ground at the end of winter), it quickly creates a great dome of arching, brilliant green foliage to 1.5m, which by midsummer transforms itself into an explosive fountain of silver flower heads up to 2m. It’s happy in moderately dry to poorly drained soils.

Calamagrostis x acutiflora ‘Karl Foerster’
Considered by many nurseries around the world to be their best-selling grass, this deciduous species starts out in spring as an erupting mound of low-grade leaves to 70cm that you’d swear was a threatening weed, only to then excel itself with purple gnat-like flowers atop wire-thin stems to 2m that stand bolt-upright as they develop into golden seed heads. It’s best used in sweeps or clumps, or as repeated individual plants. It copes with a wide range of soil conditions and soil moisture but requires a cool winter to flower well.

Medium grasses (80cm–1.2m)

Common tussock grass (Poa labillardierei)
Poa lab, as it’s known in the trade, is capable of arresting beauty, despite frequently being devalued in plantings next to freeways that receive little to no maintenance. ‘Suggan Buggan’ is a particularly good grey-leafed selection, but all are good if cut back hard every year to avoid being totally overtaken by their old, dead leaves and flower heads. It has super-fine leaves to 80cm, and modest flowers to 1.2m. Good drainage is required, but it’s otherwise unfussy about soil.

Jarava ichu syn. Stipa ichu
This grass has very fine leaves to 50cm, which give rise to silvery feathers about 1m tall that bounce and ribbon in the breeze. It’s fabulous among mixed perennials. Good drainage is required and it’s very drought tolerant.

Blue oat grass (Helictotrichon sempervirens)
Helictotrichon has an almost identical form to the desirable Celtica gigantea (syn. Stipa giantea), but at a much more modest height. Foliage is strikingly silver to 60cm, making for a pronounced contrast with the widely and elegantly spaced golden seed heads that grow to 1m. It requires perfect drainage and is best in moderately ‘hungry’ soils.

Low-growing ornamental grasses (below 80cm)

New Zealand sedge (Carex testacea)
The carexes are technically sedges rather than ornamental grasses, but they look exactly like a grass and can be used like a grass in the garden. Carex testacea creates a perfect dome of fine, bronze-tinted foliage to 60cm that turns strikingly orange in cold weather. Both the colour and the strong shape of this sedge make for a powerful statement in broad-scale plantings. C. ‘Frosted Curls’ is nearly identical but for its silver-grey colouring. Both cope with damp to wet soils through to substantially dry conditions. (Note: It is a declared weed in Tasmania.)

Carex ‘Feather Falls’
A recent introduction, this one has clear variegation on arching evergreen leaves just 30cm high. Early feedback from home gardeners suggests this grass is super tough under a wide range of conditions, creating a reliable cascade of smart leaves that recover rapidly from any necessary cut back. It will cope with a range of soil conditions, from damp through to substantially dry.

Blue fescue (Festuca glauca)
A striking blue-grey grass with leaves to 20cm, giving rise to golden flowers at 30cm. Like most blue or grey grasses, Festuca glauca is at its best when young, before it becomes congested with dead leaves. Replacement every two or three years with self-sown seedlings (nearly always guaranteed) is the best management strategy. Soil must be at the drier end of the spectrum and very well drained.