Ornamental grasses are the garden designer's best kept secret. They add texture and movement to borders, help give your garden a cohesive look and pair well with a wide range of plants. Read this guide to find out how to use them in your garden.
Other than the ubiquitous lawn (the mowing of which may be a fortnightly ritual or a chore depending on your perspective), grasses are often overlooked in garden designs. Many people fill their beds with flowering perennials and shrubs, then wonder why their garden doesn't look quite so put together as the garden designs they see at flower shows or stately homes.
The answer is often ornamental grasses. This broad group of plants often goes unnoticed, but they play an important supporting role to the bold, eye-catching flowers that stop people in their tracks, as well as linking different elements of a garden to give a cohesive feel. Grasses are tactile, sensory plants, and when I see them planted in large swathes, it invokes a childhood nostalgia of running through meadows or sand dunes.
Perhaps one reason grasses aren't common in your average UK garden is because people are unsure about how to use them. If that's the case with you, I hope this guide will help demystify this group of plants and give you some ideas for your own garden.
What are ornamental grasses?
Ornamental grasses are a group of plants that include "true" grasses, sedges and rushes. Bamboo is also botanically a grass, but it's usually treated as a woody plant due to its size and habit.
Within this category, ornamental grasses vary considerably, from the towering, feathery plumes produced by Cortaderia selloana 'Alba' to the gentle, shimmery foliage of Stipa tenuissima 'Pony Tails' and the vibrant, spiky blades of Festuca glauca 'Intense Blue'. There are grasses for sun-soaked borders, shady spots and waterside gardens.
Deciduous vs evergreen ornamental grasses
Deciduous and evergreen grasses both have specific advantages for your garden. Depending on the size of your garden and what you want grasses for, you may choose either or both types of ornamental grass.
Most ornamental grasses are deciduous, but many of these offer interest well into the winter months. In spring, new shoots emerge, followed by lush green growth and flowers in summer. Deciduous grasses often look their best in autumn, when they take on bronze and gold hues that reflect the late-season light. Examples of deciduous grasses include Stipa tenuissima, Miscanthus sinensis, Panicum virgatum and Hakonechloa macra.
Evergreen grasses give year-round colour. They're useful in mixed borders, as they offer colour and interest when other herbaceous perennials die back. While some offer seasonal variations in colour, many hold the same colour year round. Examples of evergreen grasses include Festuca glauca, many Carex sedges, yuccas and pampas grass.
How to use ornamental grasses in your garden
Ornamental grasses are incredibly versatile and can fulfil many roles in your garden. Before choosing which grasses to plant, first think about why you need them. For example, you may plant grasses:
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To create privacy or separate garden zones: Tall grasses, such as Calamagrostis 'Karl Foerster' and Miscanthus sinensis 'Gracillimus', can act as an informal screen, separating areas of your garden and adding privacy, for example, around a seating area.
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As a sensory feature: With tactile foliage and feathery plumes, soothing rustling or whistling sounds, and gentle movement in the wind, grasses are a key element of sensory gardens, meditative retreats and spaces designed for children.
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To soften hard lines and boundaries: Plant low-growing ornamental grasses next to paved areas to blend hard and soft landscaping elements.
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As a backdrop to other plants: Grasses offer a soft, natural backdrop that allows brighter flowers and other plants to pop.
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To fill out a mixed border: A border packed with different flowering perennials can sometimes look a little busy. Ornamental grasses can fill the space between more decorative plants, so your border looks full without being too busy.
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For late-season interest: Many grasses look their best in late summer and early autumn. When paired with perennials that flower at the same time, you can create a striking bed or border that shines when spring and summer-focused flower beds are fading.
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As a feature or focal point: Some garden styles, such as prairie designs, have ornamental grasses as a core feature. Grasses can also be used to frame a focal point or create a "corridor" leading from one part of a garden to another.
Once you've decided how you want to use grasses in your garden design, you can choose species that are fit for purpose and will grow well in your soil and climate. To make the most of your grasses, here are some other things to bear in mind when buying and planting ornamental grasses:
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You may need to buy more plants than you think. For grasses to act as a unifying element in your garden design, you need plenty of them. Rather than dotting individual plants randomly around your borders, plant them in groups of three or five plants, interspersed with other perennials, and then repeat the pattern down your border.
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Check how long they take to grow. Most ornamental grasses are fast-growing and reach their mature size in three years. If you're prepared to be patient, you can buy young plants in 9 cm pots, which is much cheaper than buying mature plants, particularly if you need a large number. For an instant designer-garden look, opt for plants in 3-litre or 5-litre pots, which will give immediate impact.
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Choose hardy grasses in colder parts of the UK. Many ornamental grasses are fully hardy, but some are more vulnerable to cold and require winter protection. If your garden microclimate is very mild, you may get away with growing these grasses outside year round, but in cooler parts of the country, check that your preferred grasses will survive your winters.
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Many grasses change colour in different seasons. Consider this when choosing companion plants for your grasses (or grasses for your feature plants), and you can make sure your bed looks good in spring, summer and autumn.
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Choose your planting spot based on where the sun rises and sets. Forget pumpkins and amber leaves; for me, the ethereal golden glow of grasses backlit by late-afternoon sunshine is one of the most magical autumnal experiences. If possible (and I appreciate in many gardens it may not be), plant your ornamental grasses along a western border or boundary to catch the late afternoon and evening sun, or along an eastern border or boundary to catch the morning sun.
Grasses for different situations
Ornamental grasses are generally tolerant plants, but some species are better suited than others to extreme conditions. The "right plant, right place" mantra is as true for grasses as any other plant, so with that in mind, here are some recommendations for where to plant different types of ornamental grass.
Drought tolerant grasses
While most ornamental grasses like an open, sunny aspect, they're not all drought tolerant. Grasses for dry gardens often come from Mediterranean or desert climates and have special adaptations to cope with very hot, dry conditions. Grey or blue-green foliage is a key indicator, along with narrow, spiny foliage or a waxy coating on the leaves.
Cultivars of Festuca, such as Festuca glauca 'Elijah Blue', are some of the most popular and reliable grasses, as they can handle colder winters as long as they're planted in very well-drained soil. Yuccas are popular houseplants, but you can grow hardy varieties, such as Yucca filamentosa 'Color Guard', outdoors in most parts of the UK.
Pennisetum grasses also thrive in hot, sunny gardens, but they're not as hardy as Festuca. Also known as fountain grass, Pennisetum is grown primarily for its fluffy flowerheads. Pennisetum 'Hameln' has a compact, rounded form and produces a generous amount of flowers – it is also one of the more reliable cultivars in colder areas.
Many stipas are also drought tolerant, including the architectural Stipa gigantea and the lower-growing (and ever popular) Stipa tenuissima. If you like the look of Carex but want a more drought tolerant alternative, plant Lomandra longifolia 'White Sands'. While technically a perennial, it has strappy variegated foliage that looks similar to many sedges.
Hardy grasses for cold winters
Most ornamental grasses sold in the UK are hardy enough to survive average winters, but there are a few exceptions. Pennisetum (fountain grass) is the most popular borderline hardy grass. You can grow it outside in mild parts of the UK, but it's unlikely to survive cold winters.
Soil type plays a big part in how well grasses survive a UK winter, as the combination of wet ground and cold temperatures can kill off even hardy grasses. On sandy, free-draining soil and in gravel gardens, you may be happily surprised at how well grasses survive freezing temperatures.
The hardiest grasses, capable of surviving temperatures down to -20°C, include Hakonechloa macra, Calamagrostis x acutiflora 'Karl Foerster', Mollinia caerulea cultivars, Miscanthus sinensis cultivars like Miscanthus 'Morning Light' and Cortaderia selloana varieties such as Cortaderia 'Rosea'. Carex oshimensis and Carex morrowii cultivars are fully hardy evergreen options.
Ornamental grasses for shade
True grasses don't love shade, though some varieties of Miscanthus and Molinia will grow well in light shade, such as that case by fences and walls, in open areas where there is still plenty of light. A better option for shady parts of a garden, particularly under trees, are sedges, such as Carex, Ophiopogon (black mondo grass) and Hakonechloa macra.
These three ornamental grasses have distinct differences, which helps when deciding which of them to grow. Hakonechloa macra is the darling of the designer world, with its graceful, cascading foliage in shades of green and gold. This versatile grass grows well in both sun and shade, making it a good option for creating a cohesive look in gardens with sunny and shady borders.
Ophiopogon planiscapus 'Nigrescens' is a low growing ornamental grass with near-black, strappy foliage. It's happy growing in both sun and shade, though you may notice the leaves turn more purple-green in shady areas. The striking evergreen foliage particularly suits contemporary, minimalist planting schemes.
Japanese sedge grasses, such as Carex morrowii 'Ice Dance' and Carex oshimensis 'Evergold', grow well in shade, including the dry shade found under large trees and shrubs. These evergreen, variegated varieties form attractive, bright groundcover. Carex oshimensis 'Everillo' is another good variety with vibrant lime-green foliage. The bronze-hued New Zealand hair sedges can tolerate partial shade, but their colour is richer when grown in full sun.
Grasses for wet soils
As with shade, boggy areas are not a natural home for most true grasses, so look to sedges, reeds and grass-like perennials to fill gaps in wetter parts of your garden. Acorus gramineus 'Golden Delight' is a hardy perennial grown primarily for its arching, yellow-green grass-like leaves. It will happily grow in boggy parts of your garden or even partially submerged around the edge of a pond.
Most varieties of Carex grow well (indeed prefer) moist soils, but for permanently damp ground and waterside planting, Carex elata 'Aurea' is your best bet. It can tolerate periods of submersion, as well as drier conditions (once established), and its bright golden-green foliage lights up shady areas.
Whilst not up to full submersion or waterlogged soil, Molinia caerulea 'Heidebraut' (purple moor grass) prefers moist soil over dry soil in summer, though it must be reasonably well drained in winter.
Ornamental grasses for containers
You can grow many grasses in pots, provided you choose a large enough container. Low-growing ornamental grasses, such as Ophiopogon and Festuca, are natural choices, along with Stipa tenuissima and Hakonechloa macra. Grasses with a drooping or weeping habit, such as Carex comans 'Bronze Form', often look better planted in pots than in the ground, as the foliage spills over the side of the container. Compact varieties of miscanthus, like Miscanthus sinensis 'Little Zebra', grow well in containers and require little attention.
Carex sedges are a good option for evergreen pots – I planted Carex 'Ice Dance' with Euonymus 'Green Spire', Heuchera 'Timeless Treasure' and Lysimachia 'Aurea' for a year-round foliage container. Uncinia rubra 'Everflame' is another evergreen sedge that adds colour to winter pots with its reddish-brown leaves.
You can grow borderline hardy grasses in containers in cooler parts of the country, as long as you have a greenhouse or a sheltered, mild place to keep them over winter. Imperata cylindrica 'Red Baron' is a striking deciduous grass with green, upright leaves. The blood red colour on the tips gradually spreads down the leaves as the summer progresses.
Grasses for different garden designs
Ornamental grasses are extremely varied, and you can buy grasses to suit almost any planting scheme. Here are some ideas on which grasses suit different styles of gardens and what to plant with them.
Prairie gardens
Grasses are the stars of prairie-style gardens, which take inspiration from the North American plains. Prairie plants can handle hot, dry summers, cold winters and windswept conditions, and the naturalistic planting style is relatively low maintenance, which makes it a popular planting scheme for public spaces in cities.
Prairie plants require a sunny area with well-drained soil. Plant drifts of grasses at various heights to create a layered effect with plenty of movement. Panicum 'Northwind', Miscanthus sinensis and Stipa gigantea add height with shorter grasses like Stipa 'Pony Tails'. These grasses look their best in late summer, so combine them with colourful perennials like echinacea, rudbeckia and Verbena bonariensis, which flower at the same time.
Mediterranean gardens
Mediterranean plants have similar demands to prairie plants, though many prefer milder winters. If you have a mild, sheltered garden, then Pennisetum cultivars will thrive alongside Briza media, and Festuca glauca. Many of these will grow as well in pots as in the ground if you have a patio or courtyard garden.
Combine ornamental grasses with evergreen shrubs like rosemary and lavender, and olive or palm trees to add year-round structure and colour to your garden. Choose plants with soft, silver foliage like Stacys and Senecio for texture, and plant flowering perennials, such as salvias and Echinops, for colour.
Contemporary gardens
Modern garden designs focus on simplicity and structure, with fewer varieties of plants, but lots of repetition. Depending on the aspect of your garden and your soil type, you could opt for a light prairie feel, combining feathery Stipa tenuissima with structural perennials like kniphofia, or create a green monochromatic scheme with Carex and Hakonechloa macra (either in green or the gold variety Hakonechloa 'All Gold').
Calamagrostis 'Karl Foerster' is a popular choice for adding height and structure to contemporary gardens. At the other end of the scale, the dark-leaved, compact Ophiopogon 'Nigrescens' offers dramatic contrast when planted alongside snowdrops and white tulips.
Cottage gardens
Grasses may not be the first plants you think of when conjuring an image of an English cottage garden, and traditionally, they were rarely found in borders. However, the golden rule of cottage gardens seems to be that there are no rules, and in recent years, ornamental grasses have worked their way into many cottage garden designs. In particular, they're often used in contemporary cottage gardens; a style that uses repetition and a more restricted palette of perennial plants to create a more structured, cohesive design.
Cottage gardens traditionally use local plants, so look for native species when choosing ornamental grasses. Purple moor grass (Molinia caerulea) and tufted hair grass (Deschampsia cespitosa) both form dense tufts of foliage with tall, slim stems and shimmering plumes of flowers in summer that offer an airy, neutral accompaniment to alliums, roses, phlox and other cottage garden staples.
Japanese-style gardens
Although many Japanese garden designs eschew grasses altogether, there are several ornamental grasses that suit our maritime climate very well. Hakonechloa macra and its cultivars originate from Japan's mountain forests and look wonderful planted with hostas and ferns in a shady border. They're also an excellent choice for underplanting Japanese maples, flowering cherries and other trees.
Japanese sedges (Carex oshimensis) are also useful grass-like plants for shadier parts of the garden. The evergreen foliage may be green (Carex 'Intense Green'), chartreuse (Carex 'Everillo') or variegated. Use them as groundcover or pair them with hydrangeas and camellias for a low maintenance border.
In sunnier gardens, Imperata 'Red Baron' earns its slightly macabre name of Japanese blood grass during the summer when the green blades of grass turn a deep crimson red.
