Stargrass (Heteranthera zosterifolia): Species Profile & Care

Stargrass Heteranthera zosterifolia
Stargrass (Heteranthera zosterifolia). Biodiversity Heritage Library, CC BY 2.0

Stargrass (Heteranthera zosterifolia) is a captivating freshwater aquarium plant native to South America, widely cherished for its vivid green color and star-shaped leaves, which give it its common name. Thriving in a wide range of water conditions, Stargrass is particularly favored for its rapid growth and ease of care, making it a popular choice among both novice and experienced aquarists. 

This plant is highly adaptable, capable of growing both submerged and partially submerged in water, allowing for versatile aquascaping opportunities. When provided with ample lighting and nutrients, Stargrass can transform an aquarium landscape with its lush, bushy appearance, and it also serves as an excellent habitat for fish and invertebrates, offering them shelter and spawning grounds. Furthermore, its ability to absorb excess nutrients from the water makes it an effective natural water purifier, contributing to the overall health of the aquarium ecosystem.

Common Name(s)Stargrass
Scientific NameHeteranthera zosterifolia
OriginSouth America
Ease of GrowingMedium
AquascapeForeground / Midground
Height20-30 cm (8-12 inches)
Water pH6.5 – 7.5
Temperature20°C – 28°C (68°F – 82°F)
Growth RateFast
PropagationStem Cuttings
Light RequirementHigh
CO2 RequirementRecommended but not strictly necessary

Stargrass Care

Stargrass is relatively easy to grow in an aquarium setting, thriving best under medium to high lighting conditions to prevent leggy growth and encourage dense, bushy formations. Stargrass benefits from a nutrient-rich substrate and regular fertilization with macro and micronutrients, especially when aiming for rapid growth. CO2 supplementation can further enhance its growth rate and overall health, although it’s not strictly necessary for the plant to survive. Regular trimming is recommended to maintain its shape and promote thicker growth. 

With these conditions met, Heteranthera zosterifolia can be a low-maintenance addition to both novice and experienced aquarists’ tanks, offering a stunning backdrop or mid-ground coverage that competes well with algae and provides shelter for fish and invertebrates.

Lighting Requirement

Stargrass is a popular aquatic plant used in aquariums and aquatic gardens for its attractive, bright green, star-shaped leaves and its capability to create a dense carpet or bush-like appearance under optimal conditions. Lighting is a crucial factor for the growth and health of Stargrass, influencing not only its growth rate but also its morphology and coloration.

Optimal Lighting Conditions

  • Intensity: Stargrass thrives under medium to high light conditions. It requires an intensity of about 30-50 micromoles of PAR (Photosynthetically Active Radiation) for moderate growth. However, to achieve lush, compact growth and to prevent leggy stems, higher light levels of 50-70 micromoles of PAR or more are recommended. In aquarium terms, this often translates to 0.5-1 watt per liter of water, depending on the efficiency and type of lighting used (LED, T5, etc.).
  • Duration: The daily duration of light should ideally be around 10-12 hours. Consistent light cycles are important to simulate natural conditions and support healthy growth. Using a timer to regulate light exposure can help maintain a consistent cycle.
  • Spectrum: While Stargrass can grow under a wide range of light spectrums, it benefits from light that leans towards the full spectrum (6500K to 7000K). This spectrum closely mimics natural sunlight and supports photosynthesis effectively. Lights that include some red and blue spectrum are beneficial as they promote stronger stem development and more vibrant leaf coloration.


  • CO₂ and Nutrients: Under high lighting conditions, the demand for CO₂ and essential nutrients (such as nitrogen, phosphorus, potassium, and trace elements) increases significantly. Adequate supplementation is necessary to prevent nutrient deficiencies and support optimal growth.
  • Algae Growth: High light levels can also encourage algae growth if nutrients and CO₂ are not balanced with the light intensity. Regular maintenance and monitoring are important to keep algae under control.
  • Acclimation: When introducing Stargrass to a new lighting environment, it’s important to acclimate the plant to avoid shock. Gradually increasing light intensity over several days or weeks can help the plant adjust without stress.

While Stargrass is adaptable to a range of lighting conditions, thriving growth requires attention to light intensity, duration, and spectrum, along with balanced CO₂ and nutrient levels. Adhering to these requirements will help ensure that your Stargrass remains healthy, vibrant, and an attractive addition to your aquatic setup.

Temperature & Water Parameters

To ensure Stargrass thrives in your aquarium, maintaining the right temperature and water parameters is crucial. Here’s a guide:


  • Optimal Temperature Range: 22°C to 28°C (71.6°F to 82.4°F)
  • Stargrass can tolerate a range of temperatures but thrives within this range. Temperatures that are too low can slow its growth, while temperatures that are too high can lead to stress and increased susceptibility to disease.

Water Parameters

  • pH Level: 6.5 to 7.5
  • Hardness: 3 to 12 dGH (degrees of General Hardness)
  • Carbon Dioxide (CO2): 20 to 30 mg/L
  • Maintaining these parameters encourages healthy growth and vibrant green leaves. Stargrass can adapt to a range of water conditions but prefers slightly acidic to neutral pH levels.

Additional Considerations

  • Nutrients: Stargrass is a heavy feeder, requiring a steady supply of macronutrients (nitrogen, phosphorus, potassium) and micronutrients (iron, magnesium) for optimal growth. Regular dosing of a comprehensive aquarium plant fertilizer is recommended.
  • Substrate: A nutrient-rich substrate can benefit root development and overall plant health.
  • Water Flow: Moderate water flow helps distribute nutrients and CO2 evenly around the plant, but too strong a flow may damage its delicate leaves.

By maintaining these conditions, you can enjoy the lush, vibrant growth of Stargrass in your aquarium. Regular monitoring and adjustments to your aquarium’s environment will help you successfully cultivate this beautiful plant.

Growth Height & Growth Rate

Stargrass can grow quite fast under optimal conditions. Here’s an overview of its growth height and growth rate:

Growth Height

  • Typical Height Range: Stargrass can grow quite tall, typically reaching heights of up to 20-50 cm (about 8-20 inches) in an aquarium setting. In some cases, with ideal lighting and nutrient conditions, it might even surpass this range.
  • Growth Form: It grows upwards towards the light, and with sufficient lighting, it will spread across the surface. If left untrimmed, it can form dense mats at the water’s surface.

Growth Rate

  • Growth Rate: Stargrass is known for its rapid growth rate, especially when provided with strong lighting, CO2 supplementation, and a rich nutrient substrate. In ideal conditions, it can grow several inches per week.
  • Influencing Factors: The growth rate of Heteranthera zosterifolia is significantly influenced by the availability of light, CO2, and nutrients. Higher light intensities, CO2 levels, and nutrient availability can accelerate its growth, making it necessary to trim it regularly to maintain the desired shape and size in an aquarium.

Maintenance and Care

  • Trimming: Regular trimming is necessary to keep stargrass healthy and prevent it from overshadowing other plants in the aquarium. Trimming also encourages it to grow more densely.
  • Propagation: It is easily propagated by cutting the stem and replanting the cuttings in the substrate. The cuttings will quickly take root and grow into new plants.
  • Lighting and CO2: To achieve its maximum growth rate and vibrant color, stargrass requires medium to high lighting and benefits from CO2 supplementation.

Stargrass is a versatile plant that can be used as a background or mid-ground plant in aquariums, depending on how it is trimmed and maintained. Its fast growth and ease of care make it a favorite among aquarists, especially those looking to create a lush, densely planted tank.

Aquarium CO2 Requirement

Aquarium CO2 injection can significantly benefit the growth and health of Stargrass, but it is not strictly necessary for all setups. Here’s a detailed look at the role of CO2 injection for Stargrass:

Benefits of CO2 Injection for Stargrass

  • Enhanced Growth Rate: CO2 injection can dramatically increase the growth rate of Stargrass, making it lush and vibrant.
  • Improved Color and Vitality: With adequate CO2, Stargrass can achieve a richer green color and show more vigorous overall health.
  • Better Adaptability: Increased CO2 levels can help Stargrass adapt better to varying light conditions and other environmental factors.

Considerations Without CO2 Injection

  • Light Levels: Without CO2 injection, it’s crucial to balance light levels carefully. Too much light without CO2 can lead to algae issues, as plants won’t be able to use all the light for photosynthesis.
  • Nutrient Balance: Ensuring a balanced supply of nutrients becomes even more critical without CO2. The plants will be more sensitive to deficiencies or excesses.
  • Growth Expectations: Expect slower growth rates. While Stargrass can grow without added CO2, its development will likely be less robust and slower compared to setups with CO2 injection.

Alternatives and Supplements

  • Liquid Carbon Products: Some aquarists use liquid carbon sources as a partial substitute for CO2 injection. These can provide some benefits but are generally not as effective as direct CO2 injection.
  • Careful Plant Selection: Pairing Stargrass with other plants that don’t require CO2 can create a balanced and sustainable aquarium ecosystem.
  • Optimize Conditions: Maximizing the efficiency of available CO2 through proper water circulation and maintaining an optimal aquarium setup can help even without additional CO2.

While CO2 injection is not mandatory for Stargrass, incorporating it can lead to significantly better growth, health, and appearance of the plant. In aquariums without CO2 injection, careful attention to light, nutrients, and other factors can still support the growth of Stargrass, albeit at a slower pace. Ultimately, the decision depends on your goals for your aquarium, the conditions you can maintain, and the effort you’re willing to invest.

How to Use the Plant in an Aquascape

Heteranthera zosterifolia, commonly known as Stargrass, is a popular aquatic plant used in aquascaping due to its bright green color and star-shaped leaves. When used effectively, it can add depth, contrast, and a focal point to an aquarium. Here are some tips on how to use Stargrass in an aquascape:

Background Planting

Stargrass grows tall and dense, making it an excellent choice for the background of your aquascape. Plant it in groups towards the rear of your tank to create a lush, vibrant backdrop. Its rapid growth will quickly fill in empty spaces, providing a thick, forest-like appearance.

Midground Accents

While Stargrass is typically used in the background, it can also serve as a beautiful midground plant, especially in larger tanks. Trim it to maintain a shorter height, and use it to create contrast with other midground plants. Its unique leaf shape can add texture and diversity to your layout.

Creating a Carpet

Although Stargrass is not a typical carpeting plant, it can be trimmed very short to create a dense, leafy carpet in the foreground of small aquariums or in specific areas of larger tanks. This requires frequent trimming to maintain its height and prevent it from overshadowing lower-growing plants.

Companion Plants

Combine Stargrass with other aquatic plants that have contrasting leaf shapes and colors to create a diverse and dynamic aquascape. For instance, pair it with fine-leaved plants like hairgrass or ferns for contrast, or with red plants to make its green leaves stand out even more.

Stargrass is a versatile and attractive addition to any aquascape. With proper care, trimming, and placement, it can transform your aquarium into a lush, underwater garden. Remember to monitor its growth and adjust your maintenance routines as needed to keep your aquascape balanced and beautiful.

Regular trimming is crucial for maintaining the health and appearance of Stargrass. Trimming encourages the plant to grow denser and bushier, making it more visually appealing. You can shape it according to your aquascape’s design needs, whether you’re aiming for a tidy, uniform look or a more natural, wild appearance.

How to Propagate

Propagating Stargrass can be both rewarding and a great way to fill your aquarium with vibrant greenery. Here’s a step-by-step guide on how to propagate Stargrass effectively:

  1. Select Healthy Stems: Look for vibrant, healthy stems from your existing Stargrass. These should be free from algae, pests, and disease. Healthier parent plants will result in more successful propagation.
  2. Trim the Stems: Use a sharp, clean pair of scissors or aquascaping tools to make a cut. You should cut the stem at a point that is a few inches long. Cutting just above a leaf node (the point where leaves emerge from the stem) can encourage the parent plant to branch out.
  3. Prepare for Planting: If there are leaves on the lower part of the cut stem, gently remove them. This prevents decay when the stem is planted in the substrate and helps in rooting.
  4. Plant the Cuttings: Use a pair of tweezers to carefully insert the cut end of the stem into the substrate of your aquarium. Make sure it’s deep enough to stand upright but not so deep that it damages the stem or the newly forming roots.
  5. Optimal Conditions: Stargrass requires ample lighting and benefits from CO2 supplementation to thrive and grow quickly. Ensure your aquarium conditions are optimal for Stargrass growth—moderate to high lighting and, if possible, CO2 injection.
  6. Growth: It may take a few weeks for new roots to form and for the plant to start growing actively. Patience is key. 
  7. Replanting: As your Stargrass grows, you can continue to trim and replant the stems to create a lush, dense carpet or background in your aquarium.

By following these steps, you can successfully propagate Stargrass and enhance the aesthetic appeal of your aquarium with its vibrant green color and unique texture. Remember, the key to successful propagation is maintaining optimal conditions for your aquarium plants to thrive.

Is Stargrass Invasive?

Stargrass (Heteranthera zosterifolia), also known as Stargrass, is a species of aquatic plant native to South America. It belongs to the Pontederiaceae family and is known for its versatility as an aquarium plant, capable of being used in various parts of an aquarium depending on pruning preferences. The plant can grow fast and is a true aquatic species, able to produce small but pretty purple flowers if allowed to reach the surface of the water​.

There’s no information regarding Heteranthera zosterifolia being considered an invasive species in the US. Typically, the invasive status of a plant is determined by its impact on native ecosystems, its ability to spread outside of cultivation, and the challenges it may pose to native flora and fauna. The absence of specific mention as an invasive species could imply it is not widely recognized as such; however, this status can vary by region and over time based on evolving ecological assessments and the spread of the species outside its native range.

For comprehensive and up-to-date information on the invasive status of specific plants in the US, checking resources like the USDA’s National Invasive Species Information Center or state-specific invasive species lists would provide the most accurate insights.

While there’s no information regarding Stargrass (Heteranthera zosterifolia) being an invasive species, according to CABI, African Stargrass (Cynodon plectostachyus) is listed as invasive in California (USA), Cuba, and Brazil. While their common names are similar, Stargrass (Heteranthera zosterifolia) and African Stargrass (Cynodon plectostachyus) are distinct plant species. 

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