Dwarf Hairgrass (Eleocharis parvula)

Choose dwarf hairgrass for a fine foreground lawn

Dwarf hairgrass (Eleocharis parvula) is a low sedge with thin, bright green, grass-like stems that spreads by runners and gradually knits into a lawn across the front of an aquarium. Botanists call the species dwarf spikerush or small spikerush; “hairgrass” is the name used in the aquarium hobby. It belongs to the sedge family, Cyperaceae, rather than to the true grasses.

Tropica’s plant profile rates dwarf hairgrass easy, gives a height of 3–10+ cm after two months in the aquarium and rates both its light and its CO2 demand as low. Tropica describes a low-growing Eleocharis that forms runners close to the parent plant, looks best planted in small bunches quite close to each other so that they gradually form a solid mass, and suits large and small aquariums alike as a foreground plant.

Check the name before you compare products

Several small spikerushes are sold as hairgrass, and the labels in the trade are not consistent. The Flowgrow aquatic plant database, citing the plant specialist Christel Kasselmann, says the plant usually sold as Eleocharis parvula is really Eleocharis pusilla from Australia and New Zealand, that true E. parvula may hardly be in the trade at all, and that more than one species probably travels under the name.

For you as a buyer, the practical point is simple: every plant in this group is planted, trimmed and propagated the same way, and the care below applies whichever name is on the label. Our photograph shows the form supplied.

Pick the pad, pot or bunch that suits your layout

One purchase supplies one unit of the format you select: one pre-grown pad, one pot or one bunch of dwarf hairgrass. The amount of plant in each unit changes with the growing season, so the photograph shows the format rather than an exact count of stems. Add several units to your basket when you want to plant a whole foreground in one go.

Match the format to the area you want to cover

A pad gives the quickest visual result because the mat has already formed. Pots and bunches cost less per unit and spread further once split, but they take longer to join up into a lawn. If you keep shrimp, look closely at the pad’s mesh after unpacking: if it is wire rather than plastic, cut the hairgrass mat free and plant it without the mesh.

Our delivery and live arrival information explains dispatch days and arrival times. Plant the hairgrass on the day it arrives; until then keep it damp, cool and out of direct sun.

Plan light, CO2 and substrate for steady spreading

Dwarf hairgrass grows in modest set-ups, but how quickly it carpets depends on light, CO2 and nutrients. Tropica rates its light and CO2 demand low, so added CO2 is not essential. Other sources aim higher: Flowgrow lists medium to high light and 6–40 mg/l CO2 for the plant it describes, and Tropica’s advice for the smaller ‘Mini’ form is moderate to strong lighting with CO2 injection for best results. The sources disagree, so treat Tropica’s rating as what the plant tolerates and the higher figures as what drives a fast, dense lawn.

Set up for the result you want

Whenever you inject CO2, raise it gradually and watch your fish: rapid breathing at the surface is a sign to turn it down. Fish and shrimp come first, whatever the plant would prefer.

Tropica says ‘Mini’ grows best in an aquarium soil and also grows in fine gravel or sand when a liquid fertiliser supplies the nutrients. Runners travel through the top layer of the substrate, so a fine, loose surface is easier for them to cross than coarse gravel. Keep the foreground in the light, too: tall stem plants or floating plants that shade the front of the tank slow a lawn down.

Match your water to the hairgrass range

Tropica publishes no temperature, pH or hardness limits for dwarf hairgrass. Flowgrow gives a full set of values for the plant usually sold under this name, collected in the table below. They are broad enough to suit most tropical community tanks and many cooler, unheated set-ups.

Nitrate means something different in a plant table: here it is a nutrient the plant takes up. Your fish and shrimp set their own upper limits, which are often lower, so keep the tank within the values your animals need.

Check your tap water first

UK tap water varies from very soft to very hard from one region to the next, and your water company publishes the hardness for your postcode. Test pH and KH before you plant, then compare your readings with the table using our water matcher; the water chemistry guide explains what each reading means. Flowgrow’s pH range stops at 7, while Tropica sets no limit at all, so treat pH 7 as the edge of the comfortable zone rather than a wall.

Although wild Eleocharis parvula grows in brackish marshes, aquarium hairgrass is grown in fresh water. Do not add salt to help it: nothing in the plant sources supports that, and most freshwater companions would suffer.

Plant small tufts for a faster carpet

Hairgrass spreads from the edges of each tuft, so many small tufts close up faster than a few large clumps. Tropica’s own instruction is to divide the pot into as many portions as necessary and plant them with tweezers.

Follow a five-step planting routine

1. Prepare the bed: level the substrate across the foreground and lower the water, or plant before filling a new tank, so you can see what you are doing.
2. Unpack and clean: take potted plants out of the pot and wash off the growing medium; rinse bunches and pads in a bowl of tank water and check for snails or debris.
3. Divide: tease or cut the clump into tufts of a few stems each, keeping some roots on every tuft.
4. Plant: push each tuft into the substrate with tweezers until the roots and base are covered, working across the foreground in small bunches quite close to each other.
5. Settle: refill gently over a plate or bag so the flow does not lift the tufts, then replant any that float.

A pad needs no splitting. Lay it flat where you want the lawn, press it down and cover the edges with a little substrate so it stays put. You can also cut a pad into smaller squares and space them out to cover a wider area, letting the runners close the gaps.

Flowgrow notes that the plant can grow above water as well as below it, which is why some keepers start a brand-new tank “dry”: the hairgrass is planted in damp soil and kept humid under a cover until it has rooted and spread, and the tank is flooded afterwards. This only suits a new, empty tank, never one that already holds animals.

Trim and divide the lawn as it spreads

Once the tufts join up, upkeep is mostly trimming, cleaning and now and then renewing the lawn. Flowgrow lists runners, splitting and cutting off daughter plants as ways to propagate it, so every tidy-up can also give you new tufts for bare patches.

Keep a regular maintenance rhythm

Tropica warns that excess organic waste must be removed from a hairgrass carpet by regular vacuuming to prevent algae and poor growth, and says a carpet can go many weeks between trims provided there is sufficient light and water circulation. Gentle flow across the foreground keeps debris moving towards the filter instead of settling in the lawn.

Clippings float and drift into filter intakes, so collect them as you cut. Put every trimming in household waste or compost it well away from water; never tip clippings into a drain, pond or stream.

Choose fish and shrimp that leave the lawn standing

A hairgrass lawn suits small, peaceful animals that browse over it rather than dig through it. Newly planted tufts have shallow roots for the first weeks, so fish that dig, sift the substrate hard or eat soft plants can lift them before the runners take hold. Browse our fish for planted aquariums and nano tank fish for species that suit a planted foreground.

Screen companions with the lawn in mind

Avoid large digging cichlids, goldfish and other big bottom-diggers, which uproot new tufts. Avoid plant-eaters too: Seriously Fish calls the silver dollar Metynnis argenteus an avid plant-eater.

Water values decide the final mix. Check each species’ temperature and pH against the hairgrass table and against each other with our tank mates tool. For shrimp-only tanks, read our shrimp-keeping guide, browse the cherry shrimp collection or the Neocaridina shrimp category.

Solve yellowing, gaps and algae early

Most hairgrass problems either show in the first month, while the plant adapts, or come from debris building up in an older lawn. Change one thing at a time and give the plant time to respond before you change another.

Pair each symptom with an action

Tropica’s notes on emersed production explain the first symptom: amphibious plants grown above water build up reserves so they can develop new leaves for their new environment. For algae in general, our aquarium algae control guide walks through light, nutrients and clean-up, and our live plants for beginners guide covers planted-tank basics.

Keep hairgrass in the aquarium, never in the wild

The true Eleocharis parvula is a rare wild plant in the British Isles. The Flora of Northern Ireland describes it growing immersed in the estuarine mud around the mouth of the River Bann, a population it calls very significant in both UK and Irish contexts, and notes that the plant has been seen by very few people. Wikipedia records its scattered distribution across Europe, North America and Asia in brackish marshes and mudflats. Aquarium plants of uncertain origin must never be mixed into habitats like that.

Dispose of trimmings safely

OATA advises never releasing aquarium animals or plants into the wild and does not recommend using aquarium plants in outdoor ponds. GOV.UK warns that dumping aquatic plants in the wild may be an offence. Put clippings and old tufts in household waste, or drain them and use them as mulch well away from ponds, streams and drains, as OATA suggests, and pour old aquarium water onto the lawn rather than into a drain or watercourse.

Answer dwarf hairgrass buying questions

What is dwarf hairgrass?

Dwarf hairgrass is the aquarium name for Eleocharis parvula, a low sedge from the family Cyperaceae, also called dwarf spikerush. It spreads by runners into a fine, bright green lawn across the foreground. Tropica rates it easy and gives a height of 3–10+ cm after two months.

How tall does dwarf hairgrass grow?

Tropica gives 3–10+ cm after two months in the aquarium, and Flowgrow says the plant usually sold under this name stays clearly under 10 cm when submerged. Trim the lawn with long aquarium scissors whenever it is taller than you want.

Does dwarf hairgrass need CO2?

Added CO2 is not essential: Tropica rates both its CO2 and its light demand as low. Stronger light and added CO2 make it spread faster and denser; Flowgrow lists 6–40 mg/l CO2 for the plant it describes.

How do I make a hairgrass carpet?

Split pots and bunches into small tufts of a few stems and plant them with tweezers in small bunches quite close together across the foreground. The runners fill the gaps and the tufts join up into a lawn. A pre-grown pad gives instant cover on the patch where you lay it.

Which format should I buy: pad, pot or bunch?

Choose a pad for instant cover on one patch, a pot for the most tufts after splitting, and a bunch for low-cost infilling. One purchase supplies one pad, one pot or one bunch, and the amount of plant in each varies with the growing season.

What water does dwarf hairgrass need?

Flowgrow gives a temperature tolerance of 12–27°C with an optimum of 20–25°C, pH 5–7 and 0–14 °dKH carbonate hardness. Tropica publishes no water limits and rates the plant easy, so treat Flowgrow’s values as the comfortable zone.

Is dwarf hairgrass safe with shrimp?

Yes. Shrimp graze between the blades without uprooting them, and the dense lawn gives young shrimp cover. If you buy the pad, look at its mesh before planting: if it is wire rather than plastic, free the mat from the mesh and plant it without it.

Why is my dwarf hairgrass turning yellow or brown?

Some older blades often yellow while the plant adapts to life underwater; trim them off and new growth follows when conditions are stable. If yellowing continues, check light on the foreground, CO2, fertiliser and debris trapped in the lawn.

Can I grow dwarf hairgrass in a garden pond?

No. Flowgrow lists its outdoor use and winter hardiness as unknown, and OATA does not recommend using aquarium plants in outdoor ponds. Keep it in the aquarium and put trimmings in household waste.

Consult the plant references

• Tropica: Eleocharis parvula — height after two months, light and CO2 demand, difficulty, runners and foreground use.
• Flowgrow: Eleocharis pusilla (“E. parvula”) — trade-name confusion, distribution, temperature, pH, hardness, CO2 and nutrient ranges, propagation and emersed growth.
• Tropica: Eleocharis acicularis ‘Mini’ — planting in portions, substrate, removing organic waste, lifting and replanting a carpet.
• Tropica: about emersed production of aquarium plants — why amphibious plants grown above water must make new leaves underwater.
• Wikipedia: Eleocharis parvula — common names, family, scattered worldwide distribution and brackish habitat.
• Flora of Northern Ireland: Eleocharis parvula — the rare estuarine population at the mouth of the River Bann.
• OATA: how to be plant wise — never releasing aquarium plants, outdoor ponds and safe disposal of plant waste and old water.
• GOV.UK: invasive non-native plant rules in England and Wales — dumping aquatic plants in the wild.
• Seriously Fish: Metynnis argenteus — silver dollars as avid plant-eaters.