Ornamental · Juncaceae
Corkscrew Rush
Juncus effusus 'Spiralis'
Keep its roots wet and never dry, and this forgiving little rush rewards you with a whole season of twisting green coils.
Full sun
Every 1–3 days
USDA 4–9
12–18 in · 30–46 cm
Overview
The first time you see corkscrew rush, its name makes perfect sense. Every leafless stem spirals and loops like a green corkscrew, rising straight from the crown in a tidy clump with almost no leaves at all. It is a rush, not a grass or a sedge, and it brings a playful movement to a planting that few other plants can offer, which makes it a lovely choice if you are just starting out.
What makes it different from most plants you might know is how much it loves a drink. At heart this is a bog and pond-margin plant, most content in ground that stays wet or even sitting in a few inches of standing water. Set it at the edge of a water feature, in a permanently soggy corner, or in a pot resting in a saucer of water, and you have given it nearly everything it wants.
It is a tough, cold-hardy perennial that holds its curls through much of the year, so you are in good company with a plant that forgives a lot. The one habit to keep an eye on is its way of sending up plain straight stems, a little nod to its wild parent. Simply pull those as they appear and the spiral character stays front and center, no fuss required.
Care
The short version: give it full sun to part shade, soil that never dries out, and a wet or boggy spot it can sit in all season long. Pull out any straight reverted stems when you see them, and divide the clump every few years to keep it happy and fresh.
Light
Give corkscrew rush full sun for the best, tightest curls, and don't worry, it still takes partial sun and partial shade in stride. The more light it gets, the denser and more lively its spiral growth tends to be.
Water
This is the piece that matters most, so let it sink in: the soil must never dry out. Keep it steadily moist to wet, or simply stand a potted plant in a saucer of water. It is perfectly happy in boggy ground and even in standing water up to a few inches over the crown, so just peek at the moisture every day or two when the weather warms.
Soil
It settles into rich, constantly moist to wet soil and isn't picky about texture, taking clay, loam, or sand all the same. A roomy pH range from 6.0 to 8.0 suits it nicely, and it thrives in bog conditions or shallow standing water.
Temperature
Corkscrew rush is wonderfully tough, shrugging off cold and heat from -29°F to 100°F (-34°C to 38°C). That hardiness means it can overwinter outdoors across much of the country with no extra protection from you.
Humidity
Everyday humidity is plenty, so there is no number you need to chase. What this plant truly cares about is wet roots rather than damp air, which makes it an easy, low-stress fit indoors or out.
Feeding
It eats lightly, so you can keep things simple. One gentle light spring application of a balanced general-purpose or aquatic-plant fertilizer carries it right through the season, and going heavier does it no favors at all.
Pruning
Upkeep here is minimal, which is a relief. Through the season, comb out or trim away dead and straight reverted stems to keep the corkscrew look crisp, then cut tatty or old clumps right down to the ground in late winter to early spring.
Repotting
Plan to divide or repot every 2 to 3 years, or whenever the center of the clump starts to die out. A bare middle, a crowded crown, or fewer new spiraled stems are all gentle signals that it is time.
Size & spacing
Clumps grow to about 12 to 18 inches (30 to 46 cm) tall and roughly as wide. Give each plant a matching 12 to 18 inches (30 to 46 cm) of elbow room so those spiraling stems have space to put on a show.
When to plant
Corkscrew rush is a hardy perennial that returns on its own, so there is no seed-starting calendar to fuss over. Set new plants out in spring once the danger of frost has passed, enjoy the loose summer flowers when they come, and divide tired clumps in spring whenever they want a refresh.
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 rarely gives you trouble, and the few signs it does show are simple to read. Dry soil and straight reverting stems cover nearly everything you will run into. Find the matching sign below and step in early, while the fix is still an easy one.
Stems browning and crisping as the plant fades
If the stems are browning, dry soil is almost always the reason, and the good news is it is fixable. This is a bog and pond-edge plant, so once the ground goes dry the stems crisp and flop, but a thirsty rush usually bounces back. Get it into wet soil right away, set a potted one in a tray of water, and once it perks up you can trim the dead stems away.
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
Don't worry if an older clump starts to die out from the middle, this happens to every rush as the crown gets crowded over a few years, and it is easy to put right. You will see a living ring of stems around an empty heart. Lift the whole thing in spring, set aside the tired center, and replant the strong outer pieces. Do this every few years and the plant stays young and lush.
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
Take heart, this is just reversion, the plant leaning back toward its straight wild parent, common rush. The spiral is a chosen form, so a happy clump will sometimes send up stiff, upright stems, and that is normal. Snip or tug those out at the base whenever you notice them, and if a clump reverts a lot, lift it and replant the curliest pieces. You really can keep the coils.
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
Here is some welcome news for homes with animals: corkscrew rush is not poisonous to pets, livestock, or people. It does not appear on the ASPCA toxic-plant lists at all. A pet that chews the wiry stems might cough up a little fiber, but that comes down to the texture, not any toxin, so you can breathe easy.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
You can relax with cats around, since there is no poison in the stems at all. If a curious cat gnaws the wiry stems and brings up a little fiber, that is just the rough texture at work and nothing harmful.
Dogs None
Dogs are in no danger here. A determined chewer might gag on the fibrous stems for a moment, but you can rest easy knowing not one part of the plant is poisonous.
Horses Safe
Horses are perfectly fine around it. Rushes like this one grow along the wet pasture edges where horses already graze, and they hold no toxin to worry about.
Rabbits Safe
Rabbits are safe with it too. Those tough, fibrous stems are more of a chew toy than a meal, and there is nothing in them that could hurt your bunny.
Livestock Safe
No need to fret over cattle, goats, or sheep. Native rushes show up in damp grazing land all the time and move through livestock without any trouble.
Birds Safe
Birds are safe around it. Rushes are a natural part of wetland life, so the plant carries no poisoning risk for them.
People Safe
People, children included, have nothing to fear from it. It isn't grown to be eaten, so there is no part to offer at the table, but a curious nibble will do no 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 handful of named corkscrew rush selections show up at nurseries, mostly differing in size, curl, and color. These are the ones worth getting to know.
Juncus effusus (common rush / soft rush)
Think of this as the plain, straight wild parent with upright green stems, and your curly corkscrew rush is the looped form chosen from it, the very same simple stems that 'Spiralis' keeps trying to slip back toward.
'Unicorn'
Raised at the University of British Columbia, this one grows a little taller at about 18 inches, with curls held a touch tighter and a deeper green than the everyday spiral.
'Big Twister'
If you love the coils, this selection gives you bigger, bolder curling stems that twist harder than the usual form.
'Blonde Ambition'
A small, variegated charmer with blonde-gold foliage, it keeps to around 6 to 9 inches tall while reaching out to about 18 inches wide.
How to propagate
There is really just one good way to grow more corkscrew rush, and the happy part is that it is quick, reliable, and easy to get right once you have the timing down.
DivisionEasy
Spring · A few weeks to a couple of months
Making more is wonderfully simple. In spring, lift the clump and gently tease the rhizomes apart, then tuck the most strongly spiraled divisions into soil you keep nice and wet. Give it a few weeks to a couple of months and a fresh division will settle in happily. It is best to skip seed, since those seedlings tend to come up straight instead of curled.
Myths
Corkscrew rush is an ornamental grass.
It is easy to assume so, but this is no grass, it is a rush in the family Juncaceae. A simple old rhyme helps you remember: rushes are round with solid, pithy stems, grasses are hollow and jointed, and sedges have edges with triangular stems. Once you feel a stem roll between your fingers, you will never mix them up again.