Creeping rush (Juncus repens) is a versatile and hardy plant noted for its use in creating carpets in aquariums. It is characterized by needle-like green leaves, medium to fast growth, and durability.
Juncus repens is a beautiful, grass-like plant. There are many pros associated with this plant: care level and maintenance are easy, tolerance to a wide range of water conditions, different growth forms, etc. On the other side, its appearance and growth rate greatly depends on lighting and nutrition.
If you are considering adding Juncus repens to your tank, then you will definitely find this article helpful. This article provides a lot of information including how to care for the plant in a home aquarium and what kind of potential problems you may have with Juncus repens.
Quick Notes about Juncus Repens
| Common Name | Juncus repens |
| Other Names | Juncus grass, Creeping rush, Lesser creeping rush, or Rush |
| Scientific Name |
Juncus repens |
| Difficulty | Easy – medium |
| Lighting | Medium |
| Optimal pH | 5.5 – 8.0 |
| Optimal GH | 0 – 18 |
| Optimal Temperature | 68 – 79 °F (20 – 26 °C) |
| Substrate | Nutrient-rich |
| Can float: |
No |
| Growth Form | Stem |
| Can Be Grown Emersed |
Yes |
| Growth Rate | moderate (submersed), fast (emersed) |
| Placement in Tank |
Mid-ground |
| Size | 4 – 16 inches (10 – 40 cm) |
| Fertilizers |
Not needed to low |
| CO2 | Not needed to low |
| Propagation | Cut stem, new growth, or lateral shoots |
| Color |
Light green |
Interesting fact: the genus Juncus includes more than 200 species of plants. Only Juncus repens has been found to be a good aquarium plant. All other species of this genus are suitable to be kept only as pond plants.
Etimology of Juncus Repens
The name Juncus has Latin roots (the Latin verb ‘Jungo’), meaning ‘to join or unite’, probably referring to the ancient use of these plants for binding things together.
Note: For example, Native Americans also used plants of this genus to weave baskets and netting chairs; the Japanese used them to make tatami mats, etc.
The species name, repens is from the Latin ‘Rēpēns’, meaning ‘Crawling’, referring to the growth habit of the plants.
Juncus includes was first described by French botanist André Michaux (1746–1802). His botanical work focused mostly on North American and Oriental plants.
Distribution of Juncus Repens
Juncus repens has a relatively limited distribution range in the World.
This plant can be found along the Gulf of Mexico coast and Atlantic coast in the Southeast United States (Alabama, Arkansas, Cuba, Delaware, Florida, Georgia, Louisiana, Maryland, Mexico Southeast, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, and Virginia), and in western Cuba.
Habitat of Juncus Repens
Juncus repens occurs in two forms terrestrial and aquatic. It is abundant in and a little out of very shallow waters of swaps, ponds, bogs, lakes, ditches, slow-moving streams, and in moist loamy soil along the edge of woods.
Water and waterlogged conditions are well known to be associated with the presence of the Juncus species.
Description of Juncus Repens
Juncus repens is a stem plant that grows in a rosette form. It contains rhizomatous growth for rapid clonal reproduction. This is a perennial herbaceous flowering plant species in the rush family Juncaceae.
- Growth form. Juncus repens can be grown emersed or submersed.
- Size: This species features a height of 4 – 16 inches (10 – 40 cm). It has narrow, flexible, and thin leaves (0.1 inches or 3 mm in width).
- Rhizome: The rhizome is short and cespitose. However, the plant can easily cover a large area by means of its vegetative shoots borne on prostrate stems with long internodes.
- Stem: Stems lax and creeping; produces new tufts of leaves as it grows. It appears as a flat, black runner.
- Leaf shape: Because of its narrow leaves, Juncus repens has a grass-like appearance. The leaves protrude from the node, parallel to a stem.
- Color: The leaves of Juncus repens are usually light-green. However, under very high light they will get reddish.
- Flower: Juncus repens is a flowering plant. They are found in dense heads. In natural conditions, flowering time begins in June and continues into October. The flower-bearing stem consists of several, four, or five, stretched internodes. The flowers are typically small (0.2 inches or 5 mm) and elliptical in shape. Each flower has rusty or straw-colored tepals that enclose the fertile stamens and gynoecium.
- Roots: The roots are adventitious and develop along the lower parts of the stem that is modified to form a rhizome.
- Seeds: The seeds are 0.3-1.5 mm long, usually ellipsoid to ovoid, and sometimes tailed.
Tank Requirements and Water Parameters
As I have already mentioned, Juncus repens can grow in emersed or submerged environments which makes this plant a great choice for garden ponds, terrariums, and paludarium setups.
You can achieve a beautiful-looking aquarium with this plant following the right approach.
Tank size:
Juncus repens can thrive in a variety of tank sizes. However, keeping it in nano tanks may be possible only in low-tech tanks. Otherwise, it may grow fast, uncontrollably, and even become invasive.
Therefore, the recommended minimum tank size is 10 gallons (~40 liters).
Water type, Temperature, Hardness, and pH:
Temperature: Juncus repens has the ability to tolerate and thrive in a wide range of temperatures, even cooler temperatures like 50 °F (or 10 °C). However, water temperature between the ranges of 68 – 79 °F (20 – 26 °C) is ideal for the plant.
pH: This plant prefers water pH in the range of 5.5 – 8.0. Basically, neutral pH is found to be more suitable. Even though, Juncus repens is a pretty hardy plant, be sure to monitor the pH level regularly with an accurate pH testing kit.
Note: The pH level of the water affects the plant nutrient uptake and therefore it is a significant factor for plant growth.
Hardness: Juncus repens is a resilient plant. It can grow in soft to hard water without problems (from 0 to 18 GH).
Lighting:
Juncus repens will thrive in medium lighting conditions (30 – 50 PAR). The plant can tolerate low lighting but it should be on the higher end. If your light is really low, you will not have any success with this plant.
Bright illumination causes faster and bushier growth with lots of runners. The availability of intense lighting allows it to attain a reddish tint once the plant gets closer to the surface.
Whereas low light will trigger upward growth. In addition, under low light, it grows very slowly.
Endeavor to provide around 8 – 10 hours of bright illumination daily with high-quality aquarium LED lighting fixtures, or any other suitable aquarium light source.
Note: While you’re at it, keep an eye out for algae growth and adjust the lights accordingly.
Related article:
Substrate:
Juncus repens is a heavy root-feeder, and as such, it requires a nutrient-rich substrate to thrive.
If you are planning to grow this plant in sand or gravel, the substrate needs to be regularly supplemented with root tabs so as to provide essential nutrients to the plant.
Some recommended soil substrates for the Juncus repens (links to check the price on Amazon):
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CO2 and Fertilization:
CO2: Definitely, Juncus repens can grow without CO2 injection. However, if you have high light, your tank must be balanced in terms of CO2 and nutrients. Otherwise, it will be covered with algae in no time.
Fertilization: The application of liquid fertilizers is optional for low-tech tanks. Once again, if you are planning to use CO2 injections you will also have to provide more light and make sure that fertilization needs are duly met. It will help you to maintain the balance in the planted tank and avoid algae problems.
Note: Although Juncus repens has a large root system, the plant also feeds from the water column. This plant does respond quite favorably to liquid fertilizers.
Important: If you keep shrimp in the tank with the Juncus repens, I would highly recommend reading my articles:
- CO2 in a Planted Tank Guide
- CO2 in a Shrimp Tank
- How Copper Affects Dwarf Shrimp
- Shrimp Safe Plant Fertilizers
The point is that a high level of CO2 and Copper (most fertilizers contain copper) is extremely dangerous to the shrimp.
Care and Maintenance of Juncus Repens
Juncus repens is easy to care for and adaptable to a variety of conditions. However, you will be required to trim the foliage from to time to prevent it from overrunning the tank.
Its growth rate is highly dependent on the intensity of lighting, nutrient availability, and CO2 supplementation.
Under low light or until it takes hold, this species is actually not a rapid grower. In some cases, it may take several weeks until you see some growth.
Under optimal conditions with high light, Juncus repens will grow so rapidly that the shoots will require constant and aggressive pruning with curved pruning scissors (link to check the price on Amazon) to maintain a short and compact grass-like form.
The good news is that when kept trimmed it will form a nice carpet. The bad news is that it is very time-consuming and requires a lot of work.
Note: Without regular pruning, the shoots will reach the surface of the water. Overgrowth is not a problem if you aim to achieve a jungle look in your aquarium; it depends on preference.
Another notable care activity is water changes. Partial water replacement is crucial since it adds more microelements (nutrition) to the water clean and improves the growth rate.
Planting Juncus Repens
This species is better suitable for placement in the midground of planted tanks due to its size and bushy appearance.
Planting. Planting Juncus repens is a straightforward process. You need to place the specimens into a substrate having a thickness of 2 – 3 inches (5 – 7 cm) to prevent difficulty in rooting.
- To plant Juncusrepens, first, untie the bunch and divide it into several portions.
- Next, disinfect or quarantine the plantlets properly (if they are not grown in vitro).
- When you are done, place the individual stems into the enriched substrate, and maintain the adequate spacing of about 2 – 3 inches (5 – 8 cm) from each other to prevent overcrowding and minimize shading.
- Place the stems 1 inch (2.5 cm) deep into the aquarium substrate to prevent difficulty in rooting.
- Avoid putting Juncus repens near tall plants that can shade them.
- Avoid putting Juncus repens too close to the glass. Once it starts to grow bushy, the glass will limit its growth form.
- Do not glue Juncus repens onto driftwood or anything else. This plant will not survive.
Propagation of Juncus Repens
Juncus repens has a proliferating habit, where the stem and leaves may vegetatively produce new plants until the plant is one great branching tangle.
The plant will produce by underwater stolons/runners that bear independent daughter plants, and these are capable of covering the aquarium substrate at a fast rate.
The numerous daughter plants can be cut off and replanted in the substrate, or allowed to run their course naturally without intervention.
You can also head cut the plant or cut the plant at each section where roots come out.
Juncus Repens and Dry Start Method
One of the methods of growing Juncus repens is a Dry Start Method. This method will provide unlimited CO2 without any need to buy anything!
Moreover, it allows growing the plant even before cycling the tank.
- Instead of immediately filling the tank with water after planting, we only need to add enough water to reach the surface of the lowest part of our substrate.
- Next, use tweezers to plant Juncusrepens and sprinkle them on top of a substrate.
- Cover the top of the tank with cling wrap to increase the humidity.
- In about 5 or 8 weeks you can flood the tank.
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Problems Associated With Juncus Repens
Emersed to submersed: A transition from emersed form to submersed form may trigger a melt of the green foliage, however, Juncus repens will recover from this state when it settles fully in the aquarium.
Solution: Be patient. Wait and the plant will bounce back.
Algae: Juncus repens is susceptible to algal growth, especially if the light is excessive and nutrients are plentiful.
Solution: Algae can be curbed by making some adjustments to the lighting intensity, regular water changes, and the introduction of algae-eaters into the aquarium.
Relocation: The root system of this plant is pretty huge. It is easy to even break its stem before pilling it out. Therefore, if you ever decide to remove or relocate it, you should be very careful or you will pull up a big part of your substrate.
Solution: The only thing I can think of is to be careful and take it out very slowly.
Fast growth/ Overgrowth: Under high lighting and CO2, Juncus repens can grow fast. So, it can fill up the tank with ease. So, it may require a lot of clipping.
Solution: The plant will require regular stem trimmings from time to time to prevent it from overtaking the whole tank. Another way to control the growth rate is by lowering the light.
Extremely slow growth rate: There are occasions where Juncus repens exhibits a much slower growth rate due to factors like inadequate nutrients and insufficient lighting.
Solution: Growing in such conditions may cause Juncus repens to deviate from its usual growth rate. Luckily, improving on the identified conditions will effectively help restore the plant’s vitality and by extension, its growth rate. This species requires sufficient light to grow maximally.
Benefits of Juncus Repens
Aquascape: The shape and form of Juncus repens will be an excellent decorative addition for the jungle aquascape. Without trimming, this plant will send its long shoots in different directions.
Prevents gas pockets: This plant has a well-developed root system that will help to break up anaerobic pockets in the substrate.
Note: Hydrogen sulfide pockets (H2S, the gas smells like rotten eggs) can be really dangerous to your fish or shrimp.
Oxygenation: Helps to generate oxygen in the tank water.
Hiding place: Serves as cover and shade for inverts and small fish. It serves as a perfect hiding place for shrimp and fish.
Foraging place: Acts as a buffet of biofilm, which is an ideal first food for newly hatched fry and shrimplets.
Not allelopathic: According to the study, Juncus repens, is not highly allelopathic. It will not suppress the growth of other plants by producing specific chemicals.
Related article:
- How to Spot Nutrient Deficiencies in Aquatic Plants
- Everything about Nitrates in Planted Tanks
- Phosphates in Freshwater Tanks
Juncus Repens and Compatible Tankmates
Juncus repens can be paired with a lot of aquatic species, though the plant is more suited for community tanks housing small peaceful fish and inverts that won’t rip their leaves apart.
- Small freshwater fish species like Otocinclus Catfish, Pygmy Cory Catfish, Ember tetra, Neon tetras, Green fire tetra, Cardinal fish, Celestial Pearl danios, Zebra Danio, Platies,
- Dwarf shrimp (Red Cherry Shrimp, Blue Velvet Shrimp, Snowball shrimp, Crystal Red Shrimp, Caridina cf. babaulti, Blue Tiger Shrimp, Malawa shrimp, Blue Bolt shrimp, Amano shrimp, Ghost shrimp, Bamboo shrimp, Vampire shrimp, etc.). Basically, you can keep any shrimp species with it. They will love to graze on Guppy grass and hide in it.
- Snails (for example, Ramshorn snails, Nerite snails, Malaysian Trumpet snails, Japanese trapdoor snails, Mystery snails, etc.).
Juncus repens is compatible with most plant and animal species that prefer low lighting. However, some snail species and herbivorous fish like Plecos, Goldfish, Cichlids, Rosy barbs, Sliver dollars, and Tilapia are likely to feed on this plant.
Juncus repens will be a good choice for freshwater crab and crayfish tanks. These animals are notorious for being very destructive in planted tanks. However, in this case, it should not be a problem.
Avoid or Be Careful:
Never attempt to keep Juncus repens with most crayfish, or freshwater crabs because they will most likely tear up the foliage and uproot the plant.
In the same vein, avoid hostile and aggressive fish species that are known plant devourers, these include Texas cichlids, Front cichlids, Jack Dempsey, Red Devil, and Oscars.
In Conclusion
Regardless of its delicate appearance, Juncus repens is relatively hardy and able to withstand a wide range of temperatures and water parameters.
This grass-like plant is rather undemanding in cultivation but may require regular pruning.
Under optimal conditions, it will take off very fast and fills up every available space in the tank if not kept under strict control.
References:
- Elakovich, Stella D. “Allelopathic aquatic plants for aquatic weed management.” Biologia plantarum31, no. 6 (1989): 479-486.
- Holm. “Juncus repens Michx.-a morphological and anatomical study.” Bulletin of the Torrey Botanical Club(1899): 359-364.
- Brady, Paul M. Pond management for sport fishing in Arkansas. US Department of Agriculture, Soil Conservation Service, 1981.
- Michaux, A. Flora Boreali-Americana: sistens caracteres plantarum quas in America septentrionali collegit et detexit Andreas Michaux. Vol. 1. Parisiis et Argentorati: fratres Levrault. BHL Reference page.: 1: 191.
- https://plants.usda.gov/home/plantProfile?symbol=JURE2
- https://herbarium.bio.fsu.edu/