Description, History & Interesting Facts:

Juncus is a genus of herbaceous plants called Monocotyledons, and because they superficially resemble grasses or sedges, they are commonly referred to as rushes. Juncus is the largest genus in the family Juncaceae, containing around 300 species which typically grow in cold or wet habitats, and in the tropics they are most common in montane ecosystems on the slopes on mountains.

The species commonly has a wide distribution across almost all of the continents, including Africa, but with the exception of Australasia and Antarctica. The cultivar 'Spiralis' doesn't occur in the wild as it is an artificial hybrid.

Carl Linnaeus first documented the Juncus genus back in the 1750's, using the Latin word ‘Juncus’ which means 'rush', in reference to the cylindrical hollow stalk-like leaves of many species. The specific epithet ‘effusus’ comes from modern Latin and means 'spread loosely' in reference to the plants sporadic growth habits.

Uses:

In the course of human history, many cultures have used various species of Juncus as material for weaving baskets and mats.

Corkscrew Rush (Juncus effusus ‘Spiralis’)

The Corkscrew Rush is a highly ornamental form of the Common Soft Rush (Juncus effuses). 'Spiralis' has no leaves, but the smooth cylindrical stems are very attractive, forming quirky corkscrews which are both upright, and prostrate, reaching up to 45cm in hight with an equal spread.  The young stems are light green, turning dark green as they mature, and rather charmingly, different stems have different degrees of spiral, ranging from a tight corkscrew to a loose wave.

Flowering is rare in this cultivar, but in late summer yellow-green to brown flowers may appear in an inflorescence in which each floral axis terminates in a single flower. Small egg-shaped seed capsules follow the flowers.

In regions with warm winters ‘Spiralis’ remains evergreen, but in cooler climates, in autumn the foliage becomes yellow then brown before dying back to the ground, and re-sprouting in spring.

In the Garden & Home:

Grown as a specimen plant ‘Spiralis’ makes an ideal container plant where its elegant growth can be shown off to great effect.

If it is sited in a bright light location ‘Spiralis’ makes a lovely indoor pot plant, and is very easy to grow as long as it is kept moist and is never allowed to dry out. Read more below about caring for it indoors.

‘Spiralis’ is also well-suited to the garden, and has the advantage of being clump-forming rather than running. It is particularly fond of any moist location, making it perfect to plant on sites that are waterlogged and do not drain. It is a magnificent marginal plant around a water feature or pond, and it can even grow with 2 to 15cm of water over the crown and works well in 8l containers or larger.

The attractive corkscrew stems last well in a vase and are used in floral arrangements.

Juncus effusus var. spiralis 'nana' Picture courtesy Chad Husby from flickrCultivation:

Indoors:

How much light does Juncus ‘Spiralis’ need?

It's important to locate your Juncus in a location that offers an hour or two of morning sunlight throughout the year. This is especially important in cold regions during autumn and winter, as although ‘Spiralis’ loves lots of water, you can overwater in cold winter regions, and a few hours of sun will reduce the risk at this time. Avoid more than two hours of direct sunlight a day during summer, as this will lead to dehydration and even sun-scorch.

If this plant is placed in a location that is too dark, it can decline rapidly - if it's difficult to read a book in the room, it'll be too dark for the plant too.

Spending time in a brighter environment will greatly improve its overall health, so in summer let your pot plant occasionally spend a few days outdoors in a sheltered semi-shaded spot. Once the temperatures drop below 10°C in autumn, it’s time to bring your baby indoors again.

What temperatures are best for Juncus?

‘Spiralis’ will grow well indoors in temperatures that are comfortable for humans. Keep the plant at a distance away from drying heaters in winter and air conditioners in summer.

How much water does Juncus ‘Spiralis’ need?

In its wild habitat Juncus can tolerate lots of water because it receives good air flow and some sun, and although it’s practically impossible to overwater a Juncus, it can happen if you are really over-jealous! Try to maintain evenly moist soil at all times, allowing the top 3 to 4cm of soil to dry between watering’s.

Symptoms of over-watering include: mouldy soil, stunted growth, and brown mushy patches. If the roots are starting to rot you can save the plant by repotting it.

Although the species can deal with short-lived droughts, it will result in an unattractive plant. Symptoms of under-watering include stunted growth, crispy patches forming on the plant, and yellowing.

Is tap water safe for Juncus?

Tap water contains chemicals like fluoride & chloride, but it can be used if it’s left to sit for 24hrs to allow these chemicals to settle to the bottom of the container. Rainwater and filtered water are good for indoor pot plants.

Always water potted plants with room temperature water, and never with cold water. This is especially important in winter.

How much humidity does Juncus ‘Spiralis’ need?

Because of the near-constant moisture in its soil, the natural humidity levels around the plant will be sufficient.  Misting the plant down occasionally on a hot and dry summers day will keep it clean and healthy, but do no continually mist the foliage as this can create a perfect environment for fungal diseases like Botrytis.

How to fertilise Juncus ‘Spiralis’

Fertilise throughout spring and summer using a balanced liquid fertiliser for indoor pot plants as recommended on the label. During winter decrease the frequency by half. 

Pruning:

For the best appearance cut out dead stems as needed, cutting the entire stem right down to its base.  When pruning, always use sterilised secateurs and make clean incisions, to reduce the chance of bacterial and fungal diseases.

When to repot Juncus ‘Spiralis’

Juncus like to be pot-bound, so only repot if you feel it's wholly necessary, or every three years or so. Repot into a pot only one size larger, using a good quality potting soil.

Outdoors:

Outdoors ‘Spiralis’ is watered, fertilised and pruned in the same manner as those growing indoors.

Is Juncus ‘Spiralis’ hardy to cold?

‘Spiralis’ is a tough and hardy plant capable of surviving extreme sub-zero temperatures throughout winter. In our warm and frost-free regions it is evergreen, but under very cold temperatures it will go brown and die down until the weather warms up in spring and growth resumes. Keep dormant plants on the dry side through winter.  

Does Juncus ‘Spiralis’ grow in sun or shade?

In the garden ‘Spiralis prefers full sun but will also grow well in semi-shade.

What soil does Juncus ‘Spiralis’ need? 

It will adapt to most garden soil as long as it can be kept consistently moist.  In sandy or impoverished garden soils dig in plenty of potting soil before planting.

Juncus Spiralis, Canna and Cape Fuchsia, Chicago Botanical Garden. Picture courtesy K M from flickrHow to grow Juncus ‘Spiralis’ as an aquatic or aquarium plant

With its spiral-shaped leaves 'Spiralis' adds a touch of whimsy and elegance to any aquatic landscape, be it in an indoor aquarium, small water feature, or a large pond outdoors.

It thrives in both still and flowing water, and can be grown partially or fully submerged in both fresh and saltwater aquariums. Its dense growth provides valuable shade and shelter for fish and other aquatic creatures. It is also known to absorb excess nutrients, helping to maintain a healthy balance in an aquarium or pond ecosystem.

The roots of the plant help to stabilise the soil alongside ponds, preventing erosion and maintaining water clarity.

Choosing the right location in your pond

The corkscrew rush thrives in full sun to partial shade, so choose a spot that receives 4 to 6 hours of direct sunlight per day.

Consider water depth

‘Spiralis’ can tolerate a wide range of water depths, from shallow to up to 30cm. However, it's important to avoid planting it in water that is too deep, as this can cause the plant to become top-heavy and unstable.

Water pH

The corkscrew rush does best when the pH of the aquarium or pond is between 6.5 and 7.5. It can tolerate a broader range, from 5.5 to 8.5, but these conditions may inhibit its growth.

Soil requirements

The corkscrew rush can be planted in any kind of terrarium substrate, such as gravel, sand, or even just classic terrarium soil mix.

If your pond outdoors has heavy clay or compacted soil, consider adding a layer of sand or aquatic soil to improve drainage. This will help prevent waterlogging and rotting of the plant's roots.

This species doesn’t anchor itself down, so it should be kept in a secure location beneath rocks and wood to prevent it from drifting.

Propagation:

Because it’s rare for this cultivar to bloom, ‘Spiralis’ won't seed everywhere but if it does bloom and you don’t want it popping up in areas around the parent plant, trim off the seed heads as they go over and the stems begin to turn brown.

Propagation is through division of the rhizomes during the active growing phase of the plant in summer. Gently brush away some of the soil to gain better access to the base between the mother and offset's root joining. While using a clean pair of secateurs or scissors, cut the stem with at least two root strands attached to its base. Set the pup in an appropriate-sized pot with adequate drainage and potting soil.

Place in a spot with bright, indirect light and keep the soil evenly moist, but allowing the top 1cm to dry out in between hydrations. After a month or two, treat it like a matured specimen.

Problems, Pests & Diseases:

This cultivar is relatively free of pests or diseases, but is susceptible to drought stress.

Curled leaves (stems) and dried brown edges

Curled leaves and dried brown edges are the result of too little water and over-exposure to the sun. This can occur indoors or outdoors if a new plant is placed immediately in too much sun, to which it is not yet acclimatised. Although Juncus can naturally do well in sun-filled locations, plants that haven't acclimatised yet will show signs of sun-scorch and environmental shock.

Older leaves (stems) go yellow and die down

Older stems can become yellow and die down, and this is a natural process. However, if the older leaves rapidly become yellow in quick succession, over-watering could be to blame.

Unhealthy looking leaves that turn yellow could also be lack of fertilisation, and if the plant has not been fed in over two months, it will begin to show signs of nutrient deficiencies

Toxicity:

Corkscrew Rush is not toxic to humans, and it’s been given a clean bill of health regarding dogs and cats. Unlike some plants that pack a punch with alkaloids or oxalates, the corkscrew rush doesn't contain these harmful compounds, so if your pet decides to sample this spiralled greenery, you're likely looking at nothing worse than a brief bout of digestive displeasure.

I always advise adult supervision of small children in the garden and home.