Ornamental grasses have never been so popular…and for good reason. They have attractive summer foliage that dances in the wind and often persists, after changing color, through the autumn and even the winter.
Plus many have feathery flowerheads that are just as long-lasting. They can create islands, hedges or screens in the garden or simply fit here and there in a flower bed. And there are varieties that are suitable for sun or shade, dry or wet soil, clay, loamy or sandy soils, cold climates and hot climates, etc. In fact, whatever your requirements, there is always a choice of ornamental grasses that will meet your needs!
Landscape architects and city planners have been at the forefront of the popularity of ornamental grasses. Many in fact include them in all their projects. Still, many home gardeners hesitate to try ornamental grasses. After all, aren’t they invasive?
The answer is yes… and no. Let me explain…
Ornamental Grasses by Category
There are, in fact, 3 categories of ornamental grasses.
Creeping Grasses
The first is creeping grasses, also called rhizomatous grasses, the ones that produce long rhizomes and quickly form large colonies. Think of the common reed (Phragmites australis), a grass often seen in roadside ditches where, in certain cases, it has been known to spread for dozens of miles (kilometres), all from a single original rhizome. Now, that’s invasive!
Clumping Grasses
These grasses grow in clumps. They do expand in diameter over time, as does any perennial, but only very slowly. So they really aren’t invasive. If they do get too big, all you have to do is divide them… just like you would divide any other perennial.
Grasses with Short Rhizomes
There is also an intermediate group: grasses with short, determinate rhizomes, sometimes called sod-forming grasses. They do expand outward, but don’t go very far, forming a tuft perhaps less dense that that of a clumping grass, but nothing truly invasive. Again, all you need is shovel to cut out any excess growth: that will put the plant back in its place.
How to Recognize an Invasive Grass
Just by looking at how this plant grows in its pot, you can see that it is a clumping grass: the leaves form a dense clump. Photo: thegardencorner.com
It is easy to distinguish between a potentially invasive grass and a clumping grass at the time of purchase. Just look in the pot. If the stems already form a dense clump, you’ll know it’s a clumping grass; if the stems are relatively close together, but without forming a real tuft, it’s a grass with short rhizomes; and if there are well separated individual stems that emerge here and there from the pot, it’s a creeping grass, likely to be at least a little invasive. Simple, isn’t it?
Three Categories
Here are three lists of popular ornamental grasses, categorized by their rooting type.
Note that the “zone” (hardiness zone). It tells which climatic zones the plants is likely to thrive in. For more informaton on hardiness zones, read Understanding Hardiness Zones
Clumping Grasses
These grasses grow in clumps and are not invasive.
- Autumn moor grass (Sesleria autumnalis) zones 4 to 8
- Big bluestem (Andropogon gerardii) zones 3 to 9
- Blue fescue (Festuca glauca) zones 3 to 8
- Blue grama grass (Bouteloua gracilis) zones 3 to 10
Drew Avery, flickr.com.
- Blue oat grass (Helictorichon sempervirens) zones 4 to 8
- Bottlebrush grass (Elymus hystrix, syn. Hystrix patula) zones 4 to 9
- Bowles’ golden sedge (Carex elata ‘Aureus’, syn. ‘Bowles Golden’) zones 5 to 9
- Chinese silver grass (Miscanthus sinensis) zones variable, 4, 5 or 6 to 9
- Clumping hardy bamboo (Fargesia spp.) zones 4 to 9
- Common rush or soft rush (Juncus effusus) zones 4 to 9
- Corkscrew rush (Juncus effusus ‘Spiralis’) zones 5 to 9
- Drooping sedge (Carex pendula) zones 5 to 9
- Elephant grass (Pennisetum purpureum) zones 8 to 10
- Feather reed grass (Calamagrostis × acutiflora) zones 4 to 9
- Flame grass (Miscanthus sinensis purpurascens) zones 4 to 9
- Fountain grass (Pennisetum alopecuroides) zones 5b to 9
- Foxtail barley (Hordeum jubatum) zones 3 to 10
- Frost grass (Spodiopogon sibiricus) zones 4 to 9
- Golden foxtail grass (Alopecurus pratensis ‘Aureovariegatus’) zones 2 to 9
- Gray sedge (Carex grayi) zones 2 to 9
- Great Basin Wild Rye (Elymus cinereus) zones 3 to 9
- Great woodrush (Luzula sylvatica) zones 3 to 9
- Hare’s tail grass (Lagurus ovatus) annual
- Japanese grass sedge (Carex morrowii) zones 5 to 9
- Large blue hairgrass (Koeleria glauca) zones 4 to 9
- Leatherleaf sedge (Carex buchananii) zones 6 to 9
- Lesser quaking grass (Briza minor) annual
- Little bluestem (Schizachyrium scoparium) zones 3 to 9
- Mexican feathergrass (Nasella tenuissima, Stipa tenuissima) zones 7 to 10
- Moor grass (Molinia caerulea) zones 4 to 8
- Oriental fountain grass (Pennisetum orientalis) zones 5b to 8
- Oshima sedge (Carex oshimensis ‘Evergold’) zones 5 to 9
- Pampas grass (Cortaderia selloana) zones 8 to 10
- Plantainleaf sedge (Carex plantaginea) zones 3 to 8
- Purple fountain grass (Cenchrus × cupreus ‘Rubrum’, syn. Pennisetum × advena ‘Rubrum’ and P. setaceum ‘Rubrum’) zones 8 to 10
- Purple moor grass (Molinia arundinacea, syn. Molinia caerulea arundinacea) zones 4 to 8
- Quaking grass (Briza media) zones 4 to 8
- Ravena grass (Saccharum ravennae, syn. Erianthus ravennae) zones 5 to 9
Krzysztof Ziarnek, Kenraiz, Wikimedia Commons.
- Reed grass (Calamagrostis arundinacea, syn. C. brachytricha) zones 4 to 9
- Rubytop (Melinus nerviglume, syn. Rhynchelytrum nerviglume) zones 9 to 11
- Sheep fescue (Festuca ovina) zones 4 to 8
- Snowy woodrush (Luzula nivea) zones 4 to 9
- Tall cottongrass (Eriophorum angustifolium) zones 1 to 8
- Tufted fescue (Festuca amethystina) zones 4 to 8
- Tufted hair grass (Deschampsia caespitosa) zones 3 to 9
- Vernal sedge (Carex caryophyllea) zones 5 to 9
Grasses with Short Rhizomes
Yes, these grasses are creepers, but they only spread very slowly. They’re sometimes referred to as sod-forming grasses to distinguish them from the more invasive creeping grasses. They can easily they can be planted in a flowerbed without fear of them trying to take over.
- Bitter switchgrass (Panicum amarum) zones 2 to 9
- Blue-green sedge (Carex flacca) zones 4 to 9
- Broadleaf sedge (Carex siderosticha) zones 5 to 8
- Giant miscanthus (Miscanthus × giganteus, syn. M. floridulus) zones 4 to 9
- Golden wood millet (Milium effusum ‘Aureum’) zones 5 to 9
- Grassy-leaved sweet flag (Acorus gramineus) zones 5 to 9
- Indian grass (Sorghastrum nutans) zones 3 to 9
- Japanese forest grass or Hakone grass (Hakonechloa macra) zones 5 to 9
- Northern sea oats (Chasmanthium latifolium) zones 5b to 8
- Palm sedge (Carex muskingumensis) zones 2 to 9
- Pennsylvania sedge (Carex pensylvanica) zones 3 to 8
- Prairie cord grass (Spartina pectinata ‘Aureomarginata’) zones 4 to 9
- Prairie dropseed (Sporobolus heterolepis) zones 3 to 9
- Sideoats grama (Bouteloua curtipendula) zones 3 to 9
- Striped tuber oat grass (Arrhenatherum bulbosum ‘Variegatus’) zones 4 to 9
- Switchgrass (Panicum virgatum) zones 3 to 9
Creeping Grasses
All creeping grasses are considered at least somewhat invasive and some are so dominant that you shouldn’t even think of releasing them into a cultivated zone without surrounding them with an impenetrable barrier of some sort. (Try sinking a large pot or bucket with the bottom removed into the ground and planting the invader inside: that will keep it in check).
- Blue joint or Canadian reedgrass (Calamagrostis canadensis) zones 3 to 7
- Bullrush (Typha spp.) zones 2 to 11
- Bushgrass (Calamagrostis epigejos) zones 3 to 9
- Canary reed grass or gardener’s garters (Phalaris arundinacea ‘Picta’) zones 2 to 9
- Common reed (Phragmites australis) zones 3 to 10
- Giant reed (Arundo donax) zones 6 to 10
- Japanese blood grass (Imperata cylindrica ‘Red Baron’, syn. ‘Rubra’) zones 5 to 9
- Lyme grass (Leymus arenaria ‘Glauca’) zones 2 to 8
- Running hardy bamboos (Phyllostachys, Pleoblastus, Sasa, Pseudosasa, etc.) zones vary according to species, from 3, 4, 5, or 6, up to 9
- Silver banner grass or Amur silver grass (Miscanthus sacchariflorus) zones 3 to 9
Seedy Invaders
So much for grasses with invasive rhizomes, but some grasses spread excessively through their seeds. The mother plant produces a huge number of seeds that sprout everywhere. This contrasts with the majority of ornamental grasses, which either only self-seed rarely under garden conditions or don’t do so at all. It’s worth dividing these plants into two groups, according to climate.
Grasses That Self-seed in Cold Climates
Leonora (Ellie) Enking, flickr.com.
These grasses can be invasive by their overly vigorous spontaneous sowing in regions with cooler climates (hardiness zones 3 to 6) and therefore require some monitoring in Canada, the northern US and northern Europe.
- Bullrush (Typha spp.) zones 2 to 11
- Foxtail barley (Hordeum jubatum) zones 3 to 10
- Golden wood millet (Milium effusum ‘Aureum’) zones 5 to 9
- Large blue hairgrass (Koeleria glauca) zones 4 to 9
- Lesser quaking grass (Briza minor) annual
- Northern sea oats (Chasmanthium latifolium) zones 5b to 8
- Prairie cord grass (Spartina pectinata ‘Aureomarginata’) zones 4 to 9
- Tufted hair grass (Deschampsia caespitosa) zones 3 to 9
Grasses that self-seed in mild climates
The following grasses also can self-seed excessively, but only where the winters are mild (zones 7-12). There is no risk in the North, because either the grass is not cold hardy (several grasses, such as purple fountain grass, are grown as annuals in the North and don’t survive the winter there) or because, even if the grass is hardy, its seeds fail to ripen in the North (the case with most miscanthus grasses).
- Chinese silver grass (Miscanthus sinensis) zones variable, 4, 5 or 6 to 9
- Flame grass (Miscanthus sinensis purpurascens) zones 4 to 9
- Hare’s tail grass (Lagurus ovatus) annual
- Mexican feathergrass (Nasella tenuissima, Stipa tenuissima) zones 7 to 10
- Pampas grass (Cortaderia selloana) zones 8 to 10
- Rubytop (Melinus nerviglume, syn. Rhynchelytrum nerviglume) zones 9 to 11
- Silver banner grass or Amur silver grass (Miscanthus sacchariflorus) zones 3 to 9
Great article! Your article helped me a lot. Thanks! will you allow it I want to share your article to my website:
gate ?? ?
???!??????????????????????????????????? gate.io ???
I found this very interesting and extremely useful – thank you!!
Thank you for this very extensive list and for including the grow zones. I’ve always been hesitant to plant grasses and have just started to add a few, but only after a lot of time consuming research.
An excellent list of grasses breaking them down into their various growth habits. A word of caution about Foxtail Barley (Hordeum) though: it’s seed heads are beautiful but when they mature they are very sharp. Dogs and some cats love to eat this grass with the seed heads often getting stuck in their esophogus. This is potentially life threatening for the pet and at the very least usually requires an expensive trip to the vet.
Yes, this! Grass awns are very dangerous for dogs.