How to Plant & Grow Needle Spikerush (Eleocharis acicularis)

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Clump of needle spikerush
Needle spikerush is a member of the sedge family and usually grows in clumps. Stefan.lefnaer, CC BY-SA 4.0, via Wikimedia Commons

A spike-like member of the sedge family, the needle spikerush (Eleocharis acicularis) is ideal for any water-type garden or environment. It works well for rain gardens, ponds, or any wetland-style arrangement.

The Eleocharis acicularis is known not only as the needle spikerush, but also the least spikerush. It is one of 16 known members of the Eleocharis species, and is further classified under the broad-ranging Cyperaceae (sedge) family. This family includes many different types of plants, most notably bulrushes and cottongrass (g. eriophorum).

Needle spikerush is native to North America, parts of South America, Europe, and south-eastern parts of Asia. It is considered one of the most common variants of spikerush found in the world.

There is some debate among the botanical community in regards to E. acicularis. Some botanists and botanical resources claim the plant has two distinct variants, one terrestrial and one which grows in an entirely submerged environment.  Others favor the stance that the underwater variety, known as hair grass, is actually a different species of spikerush: the dwarf spikerush (E. parvula). In this case, our focus is on the terrestrial plant most commonly identified as E. acicularis.

The needle spikerush resembles many other plants of the sedge family. One of its defining features is its relatively short stature. The stems rarely grow beyond the height of 4 – 6 inches. This plant generally grows in clumps and is well-liked for its ability to form a dense, lush carpet in a relatively short time frame.

The needle spikerush is recognizable by the configuration of its leaves and stems. Two thin, bladeless leaves are formed on either side of the stem, narrowing down to a papery sheath at the base. The stem itself is topped by the slightly flattened lance-tip style spike from which the plant derives its name. This spike is further covered with a number of scales, from which florets emerge, arranged in a spiral. The lowest of these florets eventually forms the flower from which a single achene, or seed, emerges. These stems form colonies, which in turn form a dense carpet of growth.

Facts, Benefits & Uses of Needle Spikerush

Green leafhopper on leaf
The leaves, stems & seed-heads of the needle spikerush provide food for a number of creatures, including this green leafhopper. Bernard DUPONT from FRANCE, CC BY-SA 2.0, via Wikimedia Commons

E. acicularis thrives in marshy areas with plenty of water available. For this reason, they can be used for a variety of purposes. The needle spikerush is most often used to stabilize shorelines, especially those with a high percentage of sand or silt.

Leaves, stems, and seed-heads provide food for a number of creatures. Among the insect consumers are several variants of leafhoppers and leaf beetles, as well as caterpillars of the yellow-collared scape moth (Cisseps fulvicollis). Entomologists with an interest in wetlands insects consider the needle spikerush a valuable aid in observing some of the rarer species of leaf cutters and leaf beetles.

The seed-heads also provide food for many species of marsh or wetland birds such as ducks, rails, coots, and geese, including the Canadian goose. The foliage and roots also serve as a food source for wetland mammals, notably the muskrat.

E. acicularis is a hardy plant with a fairly quick growth rate. Propagation through both seeds and long fibrous root systems make it resistant to most natural concerns. There are several forms of insects that consider the needle spikerush a viable food source, but it is not considered at risk for any major pests, infestations, or floral diseases.

For the cultivation of gardens, the needle spikerush can aid in anchoring the soil and providing a dense, relatively short carpet of foliage along the edge of water-based elements.  The short stature of the needle spikerush makes it an ideal form of ground cover. In the rare event that growth becomes an issue, it can be trimmed back to a preferable height with no detriment to the plant itself.

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Needle Spikerush Fact Sheet:
Perennial/ornamental grasses
USDA 3 – 9
Full sun
White, rarely visible
Spring and summer
4 – 6 inches
Seeds on soil surface, bare roots or plugs at a depth of 2 – 10 inches
pH 4.5 – 7

Needle Spikerush Growth, Hardiness & Climate

Needle spikerush in soil
Needle spikerush thrives best in loamy, sandy, or silty soil. Andrey Zharkikh / CC BY 2.0

The needle spikerush is intolerant of drought conditions and should be planted near a ready source of water. Planting in and around ponds, streams, or low marshy areas is recommended, especially given that needle spikerush can tolerate almost complete submersion. If you have an area where frequent flooding or erosion is a major concern, planting needle spikerush may be beneficial to help stabilize the area and absorb excess water.

Some sources also regard E. acicularis as an invaluable source for phytomining, as certain studies have observed that the dense colonies of mature plants can absorb heavy metals. As such, it can be invaluable for wetland remediation, as well as later harvesting of the absorbed contaminants.

In the wild, needle spikerush plants are often found around lakes, streams, bogs, and marshes. In areas where shoreline erosion is a particular concern, needle spikerush can be planted and cultivated into a thick mat to provide a widespread cover that also acts as a barrier to further erosion, thanks to the widespread root system that develops as the plants grow.

The needle spikerush is hardy in USDA zones 3 – 9, and adaptable to a wide temperature range. Some experts claim it can weather temperatures as low as -23°F, though it generally prefers warmer climates. It thrives in silty, sandy, or loamy soil, and enjoys a CO2-rich environment. Soil compositions can range from neutral to somewhat alkali. Needle spikerush thrives in sunlight, though they can exist in partial shade. However, for best results, full sun exposure is preferred, and warmer temperatures of 70 – 80°F are recommended for swifter propagation.

How to Plant Needle Spikerush

Mats of needle spikerush
Mature plants propagate in 2 ways: through seeds and roots. Both ways produce thick clumps that eventually combine to form mats. Krzysztof Ziarnek, Kenraiz, CC BY-SA 4.0, via Wikimedia Commons

E. acicularis can be planted using seeds, bare-root clusters, or plugs. The recommended seed density is between 1700 – 4800 seeds per acre. In terms of planting bare-root clusters or plugs, experts recommend planting at 6-inch intervals within the area you wish to cultivate the plant.  With plugs and root clusters, it is even possible to plant in shallow or partially submerged areas.

In warmer or drier climates, some irrigation may be required, as well as added nutrients to approximate the loamy soil substrates preferred by needle spikerush in the wild. In colder or low-moisture climates, greenhouse propagation may be necessary to begin growth. In such cases, recommendations include a moisture-heavy environment with temperatures of 70 – 80° F, followed by transplantation in late winter or early spring.

Mature plants propagate through both lightweight seeds, carried by wind and water, and fibrous, rhizomatous roots that spread underground. Both forms of propagation will promote new growth in the form of dense colonies, or clumps, that merge to form a thick and vibrant mat.

To propagate through cuttings, samples must be attained during the flowering season in order to collect the seed. Most experts recommend cultivation through root clusters or plugs as being simpler and more successful. While spring and summer are the optimal seasons for growth and propagation, E. acicularis can be planted for further growth year-round, in all but the coldest and driest climates.

How to Care for Needle Spikerush

Needle spikerush by pond
The soil around the needle spikerush plants should be kept fairly moist to encourage growth. Stefan.lefnaer, CC BY-SA 4.0, via Wikimedia Commons

In order to encourage new growth and expansion, keep the soil of the cultivation area fairly moist. Due to the high moisture tolerance of needle spikerush, moisture conditions up to and including partial flooding will permit this plant to thrive. Low water levels due to seasonal variation or lack of irrigation may result in slower growth and thinner coverage.

Needle spikerush rarely requires any form of trimming, due to its already short stature. However, frequently submerged clusters may grow longer and require a minimal amount of maintenance. If you happen to live near a body of water, or in an area that possesses a high moisture level – such as a floodplain or marshland – you may need to keep an eye out for propagation beyond the boundaries of the desired area. New shoots outside the desired area should be noted and removed, along with attendant root clusters.

There are very few diseases or pests that affect E. acicularis. However, you will want to keep a sharp eye out for leafhoppers and leafcutter beetles, as many of these species prefer members of the sedge family as a food source and may do damage to both new growth and mature plants.

Some care should be taken in the flowering season, as many forms of waterfowl, such as ducks and geese, consider the seed-heads a viable food source. It is also advisable to check the local muskrat population, as this particular water-dwelling mammal will consume both leaves and roots of needle spikerush.

How to Winter Needle Spikerush

Due to its widespread hardiness, needle spikerush requires very little in terms of overwintering. Its tolerance for temperatures as low as -23°F means that it will weather most climates. It may brown up and lose the above-ground growth in extreme cold, but as long as it is planted in soil with proper moisture, CO2, and nutrients, growth will reform when the weather warms.

Is Needle Spikerush Invasive or Toxic?

Needle spikerush is highly self-propagating and widespread. However, it is not considered an invasive species. Rather, it is considered an environmental necessity of wetland areas and is listed as a native species in most locations within the northern hemisphere.

There is some debate as to the toxicity of needle spikerush. In general, it is considered non-toxic, but also inedible for humans. However, its ability to absorb heavy metals and other toxic elements from the water and the soil can result in the presence of toxins within the plant, some of which may cause skin irritability and negative results if consumed. Care should be taken when interacting with specimens in the wild, or in known contaminated areas.

Is Needle Spikerush Edible? Do Animals Eat it?

E. acicularis is not considered consumable by humans. There are some rumors that it was at one time used as a remedy for stomach ailments and cholera among Native American tribes and natives in the Philippines. However, there is some debate as to whether it was in fact E. acicularis, or a member of the Cyperaceae family with similar characteristics.

Needle spikerush is a common food source for many forms of waterfowl and water-dwelling mammals. Ducks, rails, coots, and geese all consume needle spikerush seeds, seed-heads, and shoots. Among mammals, the muskrat in particular is known to favor needle spikerush leaves and roots for consumption.

Where to Buy Needle Spikerush & Seeds? (UK & US)

Needle spikerush is available in almost any gardening or landscaping store, though it may be out of stock during the winter months, due to the unavailability of seeds. Online stores may carry seeds, plugs, or bare root clusters. Due to its wide range of hardiness, it can be found in stores such as Home Depot within the US. Outside the US, numerous online stores carry it, particularly in the UK.  Agricultural stores, wetlands conservation sites, and specialist suppliers for water or marsh-type environments frequently stock needle spikerush.

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