Ornamental · Juncaceae
Corkscrew Rush
Juncus effusus 'Spiralis'
Keep its roots wet and never dry, and corkscrew rush gives you a whole season of twisting green coils.
Full sun
Every 1–3 days
USDA 4–9
12–18 in · 30–46 cm
Overview
One look at corkscrew rush and you'll get the name right away. Every leafless stem spirals and loops like a green corkscrew, shooting straight up from the crown in a tidy clump with barely a leaf in sight. It's a rush, not a grass or a sedge, and honestly, it adds a kind of movement to a planting that's pretty hard to find anywhere else.
So what makes it stand out from your average garden plant? Its thirst. Deep down this is a bog and pond-margin plant, happiest in ground that stays wet or even sitting in a few inches of standing water. Tuck it at the edge of a water feature, in some permanently soggy corner, or in a pot resting in a saucer of water, and it won't ask for much else.
It's a tough, cold-hardy perennial that keeps its curls for most of the year, so it's a pretty easygoing plant to live with. The one thing to keep an eye on is its habit of sending up plain straight stems, a little throwback to its wild parent. Just pull those when they show, and the spiral character stays front and center.
Care
The short version: give it full sun to part shade, soil that never dries out, and a wet or boggy spot where it can sit all season. Pull out any straight reverted stems, and split the clump every few years to keep it looking fresh.
Light
Give corkscrew rush full sun for the best, tightest curls, but don't sweat it, partial sun and partial shade are fine too. The more light it gets, the denser and livelier those spirals tend to be.
Water
Here's the part that really matters: the soil should never dry out. Keep it steadily moist to wet, or just stand a potted one in a saucer of water. It's totally happy in boggy ground, even in standing water up to a few inches over the crown, so check the moisture every day or two when it's warm out.
Soil
It grows in rich, constantly moist to wet soil, and it's not picky about texture either, since clay, loam, or sand all work. A wide pH range from 6.0 to 8.0 suits it just fine, and it does great in bog conditions or shallow standing water.
Temperature
Corkscrew rush is seriously tough, handling cold and heat from -29°F to 100°F (-34°C to 38°C). That kind of hardiness means it can overwinter outdoors across most of the country without any protection.
Humidity
Regular humidity is plenty, so there's no number to chase. What this plant actually cares about is wet roots, not damp air, which is why it slots in just as easily indoors or out.
Feeding
It's a light feeder, so keep it easy. One light spring application of a balanced general-purpose or aquatic-plant fertilizer carries it through the season, and overdoing it really doesn't help.
Pruning
Upkeep is pretty minimal. Through the season, comb out or trim away dead and straight reverted stems to keep the corkscrew look sharp, then cut tatty or old clumps right back to the ground in late winter to early spring.
Repotting
Plan on dividing or repotting every 2 to 3 years, or whenever the center of the clump dies out. A bare middle, a crowded crown, or fewer new spiraled stems all tell you it's time.
Size & spacing
Clumps get to about 12 to 18 inches (30 to 46 cm) tall and roughly the same across. Give each plant a matching 12 to 18 inches (30 to 46 cm) of space so those spiraling stems have room to do their thing.
When to plant
Corkscrew rush is a hardy perennial that comes back on its own, so there's no seed-starting calendar to juggle. Just set new plants out in spring once frost danger's gone, keep an eye out for the loose summer flowers, and divide your established clumps in spring whenever they need a freshen-up.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Spring after frost danger passes
- Harvest: Inconspicuous yellowish-green to brown flowers in loose cymes, summer (roughly June to September)
Hardiness
USDA hardiness zones: 4–9
Temperature: down to -34°C
Troubleshooting
Corkscrew rush doesn't give you much grief, and the few signs it does throw are easy to read. Dry soil and straight reverting stems pretty much cover everything you'll run into. Find the matching sign below and jump on it early, while the fix is still simple.
Stems browning and crisping as the plant fades
If the stems are browning, the culprit is almost always dry soil, the number one way to lose this plant. It's built for bogs and pond edges, so the second the ground dries out, the stems brown, crisp up, and flop. Get it into wet soil right away, stand a container in a tray of water, and once it bounces back you can snip off the dead stems.
Fix:
- Move to consistently moist or wet soil immediately
- Stand container in a saucer or tray of water, or place at a pond/bog edge
- Keep soil saturated; the plant tolerates standing water up to a few inches over the crown
- Trim out dead browned stems once moisture is restored
A dead, hollow center ringed by healthy growth
Noticing an old clump that's started to die out from the middle? That's just what happens once the crown gets crowded after a few years, leaving a living ring around an empty center. The fix is easy: lift the whole clump in spring, toss the worn-out middle, and replant the healthy outer pieces. Do that every few years and the plant stays young.
Fix:
- Lift and divide the clump in spring
- Discard the dead central portion and replant vigorous outer divisions
Straight green stems pushing up among the curls
What's going on here is reversion, where the plant drifts back toward its straight wild parent, common rush. The spiral is a selected form, so a clump will throw up stiff, upright stems if it gets the chance. Just cut or pull them out at the base as they show up. And if a clump reverts in a big way? Divide it and replant the curliest pieces you can find.
Fix:
- Cut or pull out the straight reverted stems at the base as they appear
- Remove reverted growth promptly and repeatedly to keep the corkscrew appearance
- If a clump reverts heavily, divide and replant the most strongly spiraled portions
Toxicity
Got animals at home? Good news: corkscrew rush is not poisonous to pets, livestock, or people. It doesn't show up anywhere on the ASPCA toxic-plant lists. A pet that chews the wiry stems might cough up a little fiber, but that's down to the texture, not any toxin.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
No worries with cats around, because there's no poison in the stems. If a cat chews the wiry stems and brings a bit of fiber back up, that's just the texture talking, not anything toxic.
Dogs None
Dogs are fine here too. A really persistent chewer might gag a little when the fibrous stems scratch the throat, but nothing in the plant is actually poisonous.
Horses Safe
Horses have nothing to fear from it. Rushes like this grow right along the wet pasture edges where horses graze anyway, and there's no toxin in them.
Rabbits Safe
Rabbits are good with it. Those tough, fibrous stems are really more of a chew toy than a meal, and there's nothing in them that'll hurt a rabbit.
Livestock Safe
Cattle, goats, and sheep? No problem at all. Native rushes pop up in damp grazing land all the time and go right through livestock without any fuss.
Birds Safe
Birds are safe around it. Rushes are a normal part of wetland life, so there's no poisoning risk for them.
People Safe
It's not poisonous to people, kids included. Nobody grows it to eat, so there's no edible bit to hand over, but a curious nibble won't do any harm.
Generally safe around pets and people; pets that nibble the stems may occasionally vomit from the fibrous material, but the plant is not poisonous.
Varieties
A few named kinds of corkscrew rush turn up at nurseries, mostly differing in size, curl, and color. Here are the ones worth knowing about.
Juncus effusus (common rush / soft rush)
This is the plain, straight wild species with upright green stems, and corkscrew rush is just the curly form picked out of it, the same simple stems that 'Spiralis' keeps trying to slide back to.
'Unicorn'
It came out of the University of British Columbia, and it's a bit taller at around 18 inches, with curls that sit a little tighter and foliage that's darker green than the usual spiral.
'Big Twister'
If you're after extra curl, this one's grown for bigger, bolder stems that twist harder than the plain old form does.
'Blonde Ambition'
Here's a small, variegated one with blonde-gold foliage that stays around 6 to 9 inches tall while it spreads out to about 18 inches wide.
How to propagate
There's really just one good way to make more corkscrew rush, and the nice part is it's quick and dependable once you've got the timing sorted.
DivisionEasy
Spring · A few weeks to a couple of months
Want more of it? Division in spring is the way. Lift the clump, pull the rhizomes apart with your hands, and pop the most strongly spiraled divisions into soil you keep good and wet. Give it a few weeks to a couple of months and a new division will settle right in. Don't bother with seed, though, since the seedlings usually come up straight instead of curly.
Myths
Corkscrew rush is an ornamental grass.
Easy mistake, but nope, it's not a grass at all, it's a rush in the family Juncaceae. There's an old saying that sorts it out in a second: rushes are round with solid, pithy stems, grasses are hollow and jointed, and sedges have edges with triangular stems. Roll a stem between your fingers and you'll feel which one this is.