Scirpus: Planting, Growing and Caring

Botany

Bulrushes comprise around 110 species of perennial plants with long, slender stems, resembling grasses or particularly rushes. Some grow wild in France, typically in wetlands, along watercourses, on banks or in marshes. They play an ecological role by helping to maintain and stabilise banks, thus combating erosion, and providing refuge for fish and amphibians. They are little known and only a few are cultivated in gardens.

Bulrushes are fairly hardy plants, most can withstand temperatures down to -20°C, except for Scirpus cernuus, which cannot tolerate temperatures below -8°C. Therefore, except in the very mild climates of the Mediterranean basin or the Atlantic coast, it’s best to protect it in winter.

Bulrushes belong to the Cyperaceae family, which includes around 5,000 species. This is the family of papyrus (Cyperus papyrus), sedges and cotton grasses (Eriophorum). Scirpus species are very close to the genus Schoenoplectus, with which some bulrushes have been reclassified. Thus, the species Schoenoplectus lacustris and Schoenoplectus tabernaemontani are synonymous with Scirpus lacustris and Scirpus tabernaemontani.

Scirpus sylvaticus: Botanical illustration

Scirpus cernuus is commonly nicknamed Drooping Club-rush, as its foliage gracefully trails towards the ground. This is also the meaning of its species name, from the Latin cernua: “drooping”, “nodding”. In English it’s called Fiber optic grass, due to its numerous thread-like stems tipped with small silvery inflorescences, which remarkably resemble fibre-optic strands. Scirpus lacustris, meanwhile, is called Common Club-rush or Basket-maker’s Rush, as its long stems were used for chair caning and barrel-making. Moreover, bulrushes do closely resemble rushes, which like them bear long stems and thrive in wet habitats. However, they don’t belong to the same botanical family.

Bulrushes form dense clumps of long, slender stems that are particularly striking. Some species like Scirpus lacustris and Scirpus tabernaemontani are rhizomatous and spread over time, potentially forming large colonies. The height of bulrushes varies greatly: Scirpus cernuus doesn’t exceed 30 cm in height and has trailing stems, while Scirpus lacustris and Scirpus tabernaemontani form stiff stems reaching up to 1.50 m, even 2 m tall. You can rely on these to add vertical interest to pond margins.

Bulrushes generally flower in summer, between June and August, bearing brown spikelets at their stem tips, except for Scirpus cernuus, which flowers almost year-round with tiny cream-white spikelets.

The inflorescences, terminal or axillary, comprise countless spikelets (between 50 and 500!) measuring less than 4 mm in diameter, each made up of minute flowers. The perianth – petals and sepals – is reduced to small bristles (3 to 6 per flower). The flowers are bisexual: each has 1 to 3 stamens (male reproductive parts releasing pollen) and a style (female reproductive part receiving pollen). Pollination is wind-borne: the wind carries pollen to the style of another flower (anemogamous pollination). This explains why bulrush flowers are neither scented nor colourful, as these traits aim to attract pollinating insects. You’ll therefore never see insects visiting bulrush flowers.

Bulrush spikelets, more or less branched depending on species. From left to right, Scirpus cernuus, Scirpus lacustris, Scirpus tabernaemontani and Scirpus sylvaticus (photos: Krzysztof Ziarnek / AnRo0002 / R. A. Nonenmacher / Robert Flogaus-Faust)

Scirpus cernuus, S. lacustris and S. tabernaemontani have very short, almost non-existent leaves, reduced to foliar sheaths. Only their decorative stems are visible. However, some bulrushes do have proper leaves: for example Wood Club-rush (Scirpus sylvaticus) bears long, slender leaves like those of grasses.

Scirpus tabernaemontani ‘Zebrinus’ stands out with its variegated stems, green striped with yellow, giving it a highly original look. As for Scirpus lacustris ‘Albescens’, it has very pale, cream-yellow stems. These varieties are ideal for bringing light to a water garden!

The fruits of bulrushes are tiny trigonous or convex brown achenes, measuring 0.5 to 2 mm. Each achene contains a seed.

The foliage of Scirpus sylvaticus and the decorative stems of Scirpus cernuus, Scirpus tabernaemontani ‘Zebrinus’ and Scirpus lacustris ‘Albescens’ (photos: Roland.aprent / Jerzy Opioła / Krzysztof Ziarnek / David J. Stang)

The main varieties of Scirpus

The Most Popular Varieties

Scirpus cernuus - Fibre Optic Grass

The leaning scirpus, also known as nodding flatsedge, is a semi-aquatic perennial that grows on banks or slightly submerged. It forms small dense clumps, made up of stiff thread-like stems, acid green in colour, very graphic.

• Flowering time March to December
• Height at maturity 30 cm

See the product sheet

Schoenoplectus lacustris subsp. tabernaemontani Albescens

Also called Scirpus lacustris ‘Albescens’ (synonym) or Common club-rush, this variety bears stiff stems, green striate vertically with creamy white, making it particularly luminous.

• Flowering time July to October
• Height at maturity 1,20 m

See the product sheet

Schoenoplectus lacustris subsp tabernaemontani Zebrinus

This Scirpus forms upright, very vertical stems, which have the particularity of being dark bluish-green, striped with creamy white. Very original, it immediately catches the eye! It is perfect in a modern and graphic water garden.

• Flowering time July to September
• Height at maturity 1,20 m

See the product sheet

Planting

Where to Plant?

Scirpus species thrive in full sun, as long as the soil remains moist, but will also tolerate partial shade. If possible, position them in a sheltered spot to protect taller species like Scirpus lacustris from wind damage to their stems.

These plants are ideal for aquatic gardens and pond planting. Scirpus lacustris and Scirpus tabernaemontani must be submerged, with their roots in water: plant them at a depth of 20 to 30 cm. Scirpus cernuus, however, can be planted in just a few centimetres of water, partially submerged, but will also thrive in simply moist soil, making it suitable for planting outside the water, on pond edges. It also adapts well to container planting and can be grown indoors, for example in a conservatory or bright room. As its stems cascade downwards, displaying it in a hanging basket showcases its beauty perfectly.

Scirpus species are excellent water purifiers, helping to oxygenate and cleanse water. They pair well with other plants used in phytoremediation, such as reeds, yellow flag iris (Iris pseudacorus), water mint, Acorus calamus, and broadleaf cattail (Typha latifolia)…

Discover our advice sheet “8 Oxygenating Aquatic Plants for Ponds or Water Features”

When to Plant?

Plant Scirpus species in spring, around April, or in autumn, during September-October. For Scirpus cernuus, spring planting is preferable as it benefits from milder temperatures to establish, being less hardy than other species. In all cases, avoid periods of frost or extreme heat.

How to Plant?

In a pond:

When purchasing Scirpus plants, plant them promptly or store them temporarily in a water-filled container to prevent the root ball from drying out.

1. Before placing in the pond, we recommend planting the Scirpus in a perforated plastic basket, designed for aquatic plants, to aid establishment and control spread.
2. Line the base and sides of the basket with hessian (or a similar fabric if unavailable): this retains the substrate while allowing water to pass through.
3. Fill the basket with compost. Ideally, use aquatic plant compost or create your own mix using clay soil blended with compost and coarse sand.
4. Remove the Scirpus from its pot and plant it in the centre of the basket.
5. Backfill with compost and firm gently.
6. Cover the surface with a layer of gravel or volcanic rock.
7. Water or partially submerge the basket to moisten the compost thoroughly before full submersion, preventing fine particles from floating to the surface.
8. Finally, position the basket in the pond. Scirpus lacustris and Scirpus tabernaemontani should be submerged under 20-30 cm of water, while Scirpus cernuus thrives in just a few centimetres of water or on damp pond margins.

In containers:

Scirpus cernuus is best suited for container planting.

1. Soak the root ball in a water-filled container to rehydrate it.
2. Fill a pot with compost.
3. Position the Scirpus in the centre of the pot.
4. Backfill with compost and firm lightly.
5. Place a saucer beneath the pot and ensure the compost stays consistently moist.
6. You can grow Scirpus cernuus outdoors – it creates a stunning display in hanging baskets on sunny terraces or balconies – but it also adapts well to bright indoor spaces like conservatories.

Scirpus lacustris (photo Frank Vincentz)

Maintenance

Whether planted in a pond or on the banks, Bulrushes require almost no maintenance. Both Scirpus lacustris and tabernaemontani are fully hardy and need no winter protection. We simply recommend cutting back the stems to about 10 cm in late winter or early spring. This will stimulate growth and allow the plant to renew its stems.

If growing Scirpus cernuus in a pot, ensure the compost remains consistently moist. Always keep water in the saucer and add a piece of charcoal to prevent mould development. In spring and summer, you can apply a little fertiliser. If the stems begin to dry out, this indicates the compost is too dry or the temperature is too high (especially if grown indoors). In winter, if possible, place it in a cool but frost-free room, away from radiators and heat sources.

Propagation

Although it is possible to sow scirpus, this method is rarely used and we recommend division instead, a much easier and quicker technique.

Dividing clumps

If you have a scirpus that has been established for several years and has had time to grow and spread a little, don’t hesitate to divide it to obtain several young plants, share them, or relocate them to a new spot. This will help rejuvenate the clumps and give them more space. Carry this out in spring, around April.

1. Remove the scirpus from its pot or carefully dig it up;
2. Divide the clump into several sections, loosening the rootstock and cutting it with pruning shears. Each rootstock section should have a few roots and young stems;
3. Take the opportunity to remove dead or damaged stems;
4. Replant immediately on the banks or in the pond.

Association

Scirpus is perfect for creating a very natural scene on the edges of a pond, pairing it for example with reeds (Phragmites australis) and bulrushes (Typha latifolia). Their tall, lush foliage will effortlessly complement that of the scirpus. Add brightness with the beautiful variegated foliage of the reed Phragmites australis ‘Variegatus’ and enjoy the opulent, finely cut foliage of ferns, such as Matteuccia struthiopteris or Osmunda species. For flowering plants, place purple loosestrife, brook thistles (Cirsium rivulare), and meadowsweet along the banks. Enjoy the slender foliage and mauve flower spikes of Thalia dealbata, a highly elegant aquatic plant! Place water lilies (Nymphaea sp.) in the pond—their graceful flowers will be the centrepiece of this aquatic scene!

For more information and ideas, explore our advice sheets “Choosing Aquatic Plants for a Pond or Water Feature” and “10 Aquatic Plants: Submerged or Floating”.

Pair Scirpus with other aquatic or marginal plants. Cirsium rivulare ‘Atropurpureum’, Nymphaea, Butomus umbellatus, Scirpus tabernaemontani, Pontederia cordata, and Thalia dealbata (photo Lip Kee)

You can also create a modern, graphic aquatic scene with scirpus. For this purpose, we particularly recommend Scirpus tabernaemontani ‘Zebrinus’, with its green stems striped in creamy white. Pair it with the variegated foliage of Phalaris arundinacea ‘Picta’, the strikingly spiralled stems of the rush Juncus effusus ‘Spiralis’, and the tall, upright stems of horsetails, Equisetum, for a striking contrast of forms! You can also incorporate some flowering plants, such as the graphic umbels of Butomus umbellatus and the small white plumes of cotton grass, Eriophorum angustifolium.