Ornamental grasses in an Irish Garden
Ornamental grasses have become a lot more popular in Ireland, and for good reason.
Grasses bring movement, transparency and a sense of lightness to a planting scheme. Their softly coloured foliage and airy seed heads can transform a border, particularly when caught by the morning or evening sun. Most grasses also look attractive if left standing over winter.
Plus many ornamental grasses are drought tolerant and therefore won't suffer as much as other plants when we have a dry summer.
Choosing the right ornamental grass
From the architectural form of Stipa gigantea to the delicate movement of Pennisetum, grasses offer a large range of shapes and textures. Some form neat, compact clumps, while others create tall fountains or loose forms. They can provide height, screening and structure, while also creating a softer, more naturalistic feel.
There are two broad groups: cool-season and warm-season grasses. Cool-season grasses, such as Calamagrostis, Deschampsia, Stipa and Molinia, begin growing earlier in spring. Many prefer moisture and some can look less attractive during a hot, dry summer.
Warm-season grasses, including Miscanthus, Pennisetum, Panicum and Imperata, get going later in spring and really come into their own during summer. Their later emergence means it can be useful to plant spring bulbs or early-flowering perennials nearby to fill the gap.
Cool-season Grasses
Calamagrostis (Reed Grass)
Calamagrostis is an elegant ornamental grass with an upright growth habit. It thickens up every three years or so, so it is not suitable for container planting as it will outgrow the container quite quickly.
Calamagrostis x acutiflora 'Karl Foerster' is one of the most popular ornamental grasses in the world and it has become very popular in public planting schemes in Ireland. Its narrow, upright shape means it is also useful in smaller gardens where you want height without taking up too much space.
Deschampsia (Tussock Grass)
Deschampsia cespitosa is a native Irish grass, found in damp or shaded woodlands. It likes moist soils and I tend to plant it in an area that's in shade for at least part of the day.
Its delicate, cloud-like flowers look particularly lovely when they catch the sunlight.
Stipa gigantea (Giant Oat Grass)
Stipa gigantea has tall, oat-like flower heads that create a striking look. It grows to 2.5 metres and can be useful for gentle screening. It is native to the Mediterranean and, despite being a cool season grass, it likes sunny and dry spots.
Molinia (Moor Grass)
Molinia caerulea has a gentle see-through look. Its transparency means it can be nice at the front of the border as you can still see smaller plants behind it.
It is native to heaths and bogs of Ireland and therefore is happiest in damp soil. The foliage turns lovely shades of yellow and orange in autumn.
Warm-season Grasses
Pennisetum (Fountain Grass)
Pennisetum alopecuroides 'Hameln' has lovely bottle brush flowers. It is a little more tender than the other grasses on this page and more suitable to the milder areas of Ireland.
Its compact, rounded shape makes it a good choice for the front of a sunny border. It is tolerant of dry conditions once established.
Miscanthus
Miscanthus sinensis has lovely, feathery flowers in late summer and autumn. They look fantastic over winter. The leaves are also an attractive autumn colour. Its leaves are sharp, so be careful when pruning!
There are lots of varieties available in Ireland, ranging from compact plants to tall grasses that can provide screening.
Imperata
Imperata cylindrica ‘Rubra’ is a small ornamental grass, growing to about 40cm tall. The leaves become increasingly red as the season progresses, making it particularly attractive in late summer and autumn. I use it quite a lot in designs for tropical planting schemes.
Panicum
Panicum virgatum has airy panicles which are often pink or red when first opening. It works well on its own in a garden, or in a large container, or planted in large groups. It is tolerant of dry conditions once established.
Many varieties also develop beautiful autumn colours, with their foliage turning shades of red, orange and yellow as temperatures drop.
Designing with ornamental grasses
One of the things I particularly like about grasses is their ability to complement rather than compete with flowering plants.
Their fine foliage provides a beautiful foil for broad-leaved perennials, colourful flowers and shrubs.
Bulbs can also work planted very near the crown of grasses. The bulbs providing colour in the spring, and then the grasses emerge and fill the spot when the bulbs die back.
Grasses also introduce movement as the foliage moves on a breezy or windy day.
A grass backlit by the setting sun can also be spectacular, highlighting its translucent foliage and seed heads.
Maintenance of Ornamental Grasses
Most ornamental grasses are relatively low maintenance.
Many deciduous grasses can simply be cut back in early spring before new growth emerges. Evergreen grasses (such as Stipa tenuissima) are the exception: rather than cutting them back, I prefer to pull out the old, loose foliage by hand.
Grasses are generally easy to establish and can quickly reach a good size, making them particularly useful when creating a garden that needs to look established relatively quickly. However, check the eventual size and spreading habit before planting. Some grasses can be very vigorous or even invasive, either spreading by seed, or by rhizomes or stolons.
Ornamental grasses can bring structure, movement, texture, seasonal interest and a softer natural feel to almost any garden!
If you’d like advice on choosing ornamental grasses or any other plants for your garden, I offer planting scheme designs and garden consultations. I can help you choose plants that suit your garden’s conditions, your preferences and the amount of maintenance you want to do.
Please fill out this form or email me at elaine@plantplanner.ie
