Sisyrinchium, Bermudiana: planting, growing, and caring for

Botany

Sisyrinchium comprises around 200 species of annual or perennial plants, native to North and South America. They can be found in the wild in various environments: meadows, fallow land, clearings, coastal areas, mountains, etc. Most cultivated species are short-lived perennials, but there are also annual species. Sisyrinchium striatum hails from South America (Chile, Argentina…). It is among the hardiest, tolerating temperatures down to -15 °C in well-drained soil, making it a good garden plant. Sisyrinchium angustifolium is primarily found in wet meadows, clearings, and along riverbanks… It is also known as Sisyrinchium bermudiana, which has earned it the nickname Bermudiana, as it is indeed native to Bermuda, Canada, and the eastern United States.

Sisyrinchium belongs to the large family of Iridaceae (over 2,300 species), which includes herbaceous plants, often rhizomatous or bulbous. In addition to Irises, this family contains many ornamental plants: Crocus, Gladiolus, Freesia, Crocosmia, Ixia, Sparaxis, Watsonia, Chasmanthe…

Sisyrinchium angustifolium: botanical illustration

In English, Sisyrinchium is nicknamed Blue-eyed grass: the grass with blue eyes or Golden-eyed grass: the grass with golden eyes, depending on whether it is Sisyrinchium angustifolium, with blue flowers, or S. californicum, with yellow flowers. The Latin name Sisyrinchium comes from the Greek sys: pig and rhynchos: snout, as in their natural habitat, wild pigs dig into the soil in search of Sisyrinchium to consume. The species name S. striatum refers to the small stripes it bears on the underside of the petals, while S. angustifolium means “narrow-leaved.”

Sisyrinchium develops from a short, non-running rootstock. They are short-lived plants, but they tend to self-seed spontaneously without becoming invasive! Moreover, if one wishes to prevent spontaneous seeding, it is sufficient to cut off the faded flowers.

Sisyrinchiums form spreading clumps made up of upright, very fine leaves. These leaves are arranged in a fan shape. Sisyrinchiums measure between 15 and 90 cm tall. Sisyrinchium striatum is among the tallest, as it forms upright floral spikes that are quite vertical. These are slow-growing plants.

Sisyrinchium generally flowers from May – June, and in early summer, sometimes until August. For Sisyrinchium striatum, flowering occurs in June-July.

The flowering of Sisyrinchium angustifolium, Sisyrinchium striatum, and Sisyrinchium californicum (photos The Marmot / Hectonichus / Tom Hilton)

Sisyrinchium offers star-shaped, fine, and delicate flowers. They consist of three petals and three sepals that all look the same (thus referred to as six tepals). They are extended into a tube at the base. The flowers generally measure two to three centimetres in diameter. Insects pollinate the flowers of Sisyrinchium.

The Sisyrinchium striatum bears spikes made up of flowers grouped in successive whorls (5 to 15 flowers inserted together). This results in a tiered and quite graphic flowering, which has the advantage of adding verticality to the flower beds! The flowers are pale yellow, making them relatively easy to combine. The underside of the flowers bears small purplish stripes, which gives it its species name, S. striatum.

The Sisyrinchium californicum, on the other hand, offers a flowering of small bright yellow stars, very luminous. In many other species, the flowers are blue or mauve, with the centre or throat of the flower being bright yellow. This creates a lovely contrast that draws the eye! There is even a variety with pink flowers: ‘Quaint and Queer.’

After flowering, Sisyrinchium produces capsules containing round black seeds. They germinate easily and can self-seed in the garden.

The leaves of Sisyrinchium are linear, very long and fine, resembling grass leaves. They do not exceed 2 cm in width but can reach 40 cm in length, and are bluish-green in colour. They are arranged in a fan shape. Sisyrinchium striatum ‘Variegatum’ has the particularity of bearing variegated foliage. The leaves of Sisyrinchium persist in winter when temperatures remain relatively mild.

The foliage of Sisyrinchium striatum (photos Agnieszka Kwiecień / Cillas) and the fruits – capsules – of Sisyrinchium angustifolium, containing the seeds (photo Gmihail)

The main varieties of Sisyrinchium

The most popular varieties

Our favourite varieties

Sisyrinchium striatum

Sisyrinchium striatum is a South American species (Chile, Argentina) that bears cream-yellow flowers, arranged in whorls on upright flower spikes. It is taller and has a more vertical habit than other Sisyrinchium.

• Flowering time July, August
• Height at maturity 60 cm

See the full description

Sisyrinchium californicum

Native to the western United States and Canada, Sisyrinchium californicum is a charming little rhizomatous perennial that bears star-shaped, bright yellow flowers made up of six slender petals. Its brightness is much appreciated!

• Flowering time July to September
• Height at maturity 15 cm

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Sisyrinchium angustifolium Lucerne

Sisyrinchium ‘Lucerne’ bears a multitude of small mauve-blue flowers with striated petals, marked with bright yellow at the centre of the flower. It blooms for a longer period and offers slightly larger flowers than the species type, Sisyrinchium angustifolium.

• Flowering time June to August
• Height at maturity 35 cm

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Sisyrinchium angustifolium Devon Skies

Sisyrinchium ‘Devon Skies’ is a stunning variety that offers flowers made up of six very light sky-blue petals, which darken towards the centre of the flower, surrounding a yellow heart.

• Flowering time August, September
• Height at maturity 15 cm

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Sisyrinchium bellum

Sisyrinchium bellum is a small, very low variety that bears flowers in summer with blue-mauve striated petals, marked with yellow at the centre of the flower. It is also found under the name Sisyrinchium idahoense.

• Flowering time July to September
• Height at maturity 10 cm

See the full description

Planting

Where to plant?

Sisyrinchium primarily needs warmth and sunlight! Plant them in full sun, in well-draining, light soil. They tolerate poor, ordinary soils well, but still appreciate fresh soil. Regarding pH, the soil can be neutral or slightly calcareous. We recommend choosing a location sheltered from cold winds. If your soil is heavy and tends to retain water, don’t hesitate to plant on a small mound to allow for better drainage.

If you live in a region with a warm climate, such as the Mediterranean basin, you can plant Sisyrinchium in partial shade. In other regions, it’s better to avoid partial shade, as Sisyrinchium is more floriferous when in the sun!

Sisyrinchiums are perfect for rock gardens, but they can also find their place in borders or at the edge of a pond (be cautious of stagnant moisture: we recommend elevating them above the pond level). This plant is very suitable for seaside gardens and withstands heat and drought.

As it is a small perennial with delicate flowers, don’t hesitate to plant it in masses, installing a large number of young plants together! The effect will be much more impressive.

You can easily grow Sisyrinchium in pots. Additionally, this will allow you to easily shelter it from the cold in winter.

When to plant?

We recommend planting Sisyrinchium in spring, around April-May. However, if you live in a region with a mild climate where the risk of frost is low, you can plant in autumn.

How to plant?

Don’t hesitate to install several Sisyrinchium plants in the same border for a more beautiful effect. Maintain at least 50 cm distance between Sisyrinchium striatum plants, and preferably 30 cm distance for other Sisyrinchiums.

1. Prepare a planting hole about twice the size of the root ball.
2. Fill it with potting mix mixed with a bit of gravel or coarse sand for drainage.
3. Remove the Sisyrinchium from its pot and plant it.
4. Replace soil around the clump and firm it with the flat of your hand, but be careful not to bury the collar!
5. Water generously.

Continue to water regularly in the weeks following planting, until the Sisyrinchium is well established.

Entretien

Once established, Sisyrinchium requires little maintenance. It is not susceptible to diseases or parasitic issues. However, in heavy soil, its roots may rot, highlighting the importance of good drainage.

Although it tolerates drought, it will appreciate some watering in spring and early summer, which will encourage its flowering.

We recommend applying a layer of mulch around the Sisyrinchium in autumn to protect it from the cold. Similarly, in summer, the mulch will help retain soil moisture for longer.

You can also cut back faded flowers or flower spikes. However, leave some in place to allow the Sisyrinchium to self-seed.

Although they are perennials, Sisyrinchiums have a short lifespan. Generally, they do not root very well in the soil and tend to disappear after a few years. However, they tend to self-seed, particularly Sisyrinchium californicum.

Sisyrinchium bellum (photo Dvortygirl)

Multiplication

We recommend propagating Sisyrinchium by sowing. The seeds germinate easily! Some species even tend to self-seed spontaneously.

Sowing

is easy to sow; however, seed germination is quite slow: it can take between one and six months. A period of cold (vernalisation) aids germination: you can either place the seeds in the refrigerator for two to three weeks at the beginning of spring before sowing, or sow them directly in pots in autumn and then leave the pots outside to naturally experience the cold effect.

1. Prepare a pot with a light substrate, such as seed compost.
2. Sow the seeds.
3. Cover them with a thin layer of compost (ideally 6 mm thick).
4. Water gently.
5. Then place the pots under a cold frame, ensuring that the substrate remains slightly moist until germination.
6. As soon as the seedlings are large enough to handle, you can transplant them into individual pots.
7. Plant them in the garden the following spring.

Plants obtained from sowing may take two to three years before they start to flower.

Division of Clumps

You can divide clumps of Sisyrinchium in spring or late summer, after flowering. This can be done every two to three years.

1. Identify a well-developed clump of Sisyrinchium that has been in place for several years.
2. Carefully dig around it to lift it without damaging the roots.
3. If necessary, remove soil between the roots, and eliminate any faded flowers, blackened leaves, and dead roots if you see any.
4. Separate it into several fragments, ensuring that each has at least a few leaves and roots.
5. Replant immediately in a new location or in pots.
6. Water generously.

Association

With its very soft pale yellow hue, the Sisyrinchium striatum is very easy to combine in a border! It brings verticality and a delicate, light effect. It will find its place anywhere. It is ideal in a naturalistic garden with a rustic style! Moreover, it self-seeds easily. Plant it in an area of the garden where you intervene little, leaving it very natural. Pair it with other delicate flowers, such as Buenos Aires verbena, purple toadflax, Gaura lindheimeri, Sidalcea, Penstemons, or Salvia pratensis. Also integrate grasses, such as Chinese fountain grass or Stipa pennata. This will give your garden a lovely wild meadow feel!

The Sisyrinchium is ideal in a naturalistic, wild garden, alongside other very light flowers! Scene featuring Epilobium angustifolium ‘Album’, Sanguisorba ‘Red Tip’, Penstemon and Pennisetum, Knautia macedonica (photo Epibase), Salvia pratensis (photo Lubaer), Sisyrinchium striatum (photo Ghislain118) and Linaria purpurea (photo C T Johansson)

Conversely, you can also pair it with more impressive blooms, larger and brighter flowers: for example, those of gladioli, dahlias, or roses. The Sisyrinchium will add a touch of lightness alongside them!

The Sisyrinchium striatum also pairs very well with silver or purple foliage: Stachys byzantina, wormwoods, Cynara cardunculus, Cotinus ‘Royal Purple’, Physocarpus, heucheras, Euphorbia amygdaloides ‘Purpurea’… Similarly, with its delicate and natural flowering, it can fit into a romantic garden or a cottage garden. Pair it, for example, with roses, nepeta, campanulas, or alchemilla…

Since they thrive in warm, sunny situations, you can incorporate Sisyrinchiums into a Mediterranean-style garden with a mineral focus. We particularly recommend Sisyrinchium californicum, which is especially suited for seaside gardens. Plant it alongside lavenders, Armeria maritima, agapanthus, Festuca glauca, Eryngiums, santolina, and agaves. You can also create an exotic border with Crocosmias, Kniphofias, and Eucomis.

As the Sisyrinchium is not a very tall plant and has a rather discreet flowering, consider placing it at the front of borders, in front of taller plants. Also, don’t hesitate to plant it in masses for a more impressive effect!