Glorious Grasses

Paul Green, from Green's Leaves, with advice on these wonderful perennials that can offer colour and structure all year round. - 08 March 2025

Ornamental grasses have seen waves of popularity in recent years. Yet, I still think that many people don’t really appreciate the many qualities they have. There are so many grasses that give exceptional colour and form. Many of them offer different looks over different seasons.

When giving talks featuring grasses I am ready for the usual dismissive lines:

“Grasses are just for the lawn”

“They are a bunch of thugs”

“Mine died in the winter, so they can’t be hardy”

The huge choice of attractive grasses, sedges and rushes (usually lumped together as ornamental grasses when people think of them) mean there is not one homogenous cultural requirement. In other words, whatever combination of dry/wet and sun/shade you have, I’ll find you ones that will thrive. The widest choice will be in sun and moist soils.

The vast majority of the ones offered for sale are hardy and well behaved, requiring little maintenance. They don’t spread excessively fast or seed everywhere. In the same way conifers often get a bad press purely on badly managed x Cupressocyparis leylandii (or just plain 'Leylandii' to most folk), so grasses and sedges get judged on some of the Carex species, that are too prolific with seeding around, or some of the purple leaved Pennisetum selections or Imperata (blood grass) which are not suited to the climate in many parts of the UK.

While the summer and autumn are the obvious months to enjoy the herbaceous grasses and sedges, the winter display is often beautiful too. Anyone cutting herbaceous grasses down in autumn is missing so much. It’s like going out for a meal and leaving before the puddings come out!

The range of grasses at the RHS garden at Wisley  make a lovely show in the winter. Choose a nice sunny day – the richness of the colours in the golden or fawn foliage, flowerheads and stems is something else. Even on a gloomy day they seem to glow. Sure, the bright oranges, reds and blues of ‘peak season’ may have gone, but there is still so much to enjoy. Mass plantings can look amazing, but just one on it’s own can be a great contrast to other plants. All of the photos in this article were taken at Wisley in early February 2022.

February is the time to trim back your herbaceous grasses – I try to wait until the end of the month. The evergreen ones are better left until late March in my opinion – sometimes a preen may be all that’s necessary, often a full cut back rejuvenates them. Not only does leaving the foliage on for winter look good, it is better for the plants too. There are subtle differences in trimming heights, but if you’re not sure what you’ve got, a hand-high cut is the safe option. A bit lower is fine for some, but definitely not all. Feel free to bring a photo on your phone to the fairs if you need an identification.

Calamagrostis brachytrica

Propagation time is based on whether the grass is a cool or warm season grower. This is based on when the bulk of the growing is done. Look at a good book on grasses and it will list which type you have. COOL SEASON – do in early – mid spring or early – mid - autumn for best results. WARM SEASON – late spring – early summer is ideal. Sure, you can often get away with stretching these margins, but results can be more erratic.

A few of the showier genera for you to try –

Miscanthus – (warm season) – sometimes called Japanese Silver grass, they vary from small to huge They are great in sun, but far better than many think in light shade. The dwarf zebra grasses such as ‘Little Zebra’ are better bets for pots than good old ‘Zebrinus’. The modern cultivar ‘Navajo’ (1.2 m) is superb with purple-red colours in spring as well as the usual autumn time.

A mass planting of Miscanthus at the RHS gardens at Wisley

Panicum – (warm season) – the switch grasses are a personal favourite. For stunning red and purple colours later in the season go for ‘Squaw’ (1.5m), ‘Shenondoah’ (1m) or  the quick colouring ‘Hot Rod’ (1m).

Molinia – (cool season) – the moor grasses are a bit more subtle in summer, but they sure make up for it from autumn into winter. The whole plants glow golden or, in some cultivars, orange tinged. The habit ranges from upright or arching. They are incredibly hardy, preferring moist acid or neutral soil, but in practice being pretty damned tough!

There are lots of cultivars, some well over 2m, but I particularly liked the dark stems and seed heads of ‘Edith Dudszus’ which is a more compact 1.2m.

Carex (mainly cool season and a few warm season) – there is a huge range of sedges, but they are generally much shorter than the grasses you’ll see. The evergreen forms such as the shade loving C. oshimensis ‘Everillo’ (part of the EverColor series) make great under-plantings or container plants or look great along the front of beds. I’ve seen some of the arching forms (eg  sun or shade tolerant C. comans selections ‘Frosted Curls’ or ‘Amazon Mist’) used in hanging baskets – a bit different, but rather lovely.

Carex oshimensis 'Everillo' contrasting with the black, grass-like Ophiopogon planiscapus 'Nigrescens'

So treat yourself to some hard working grasses, sedges and rushes – very diverse, very addictive!

Photo: Beata Cosgrove Photography

Paul Green and his wife Helen are the owners of Green's Leaves, based in Newent in Gloucestershire. They specialise in choice and rare shrubs, coloured foliage plants, architectural plants and grasses.

Website:  www.greensleavesnursery.co.uk

Article and all photos copyright the author.