How to Plant & Grow Ragged Robin (Silene flos-cuculi)

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ragged robin blooming
Ragged robin is so named for its highly dissected, “ragged” looking flowers. gailhampshire from Cradley, Malvern, U.K, CC BY 2.0

Silene flos-cuculici is commonly known as ragged robin and is a member of the Caryophyllaceae family. This family of plants is also known as the carnation family and has a fairly cosmopolitan distribution. Ragged robin, specifically, is native to wet soils in Europe and Asia. Lychnis flos-cuculi is an old scientific name for this plant, which is sometimes still used. The word “Lychnis” comes from the Greek word for lamp, which alludes to ragged robin’s cheerful bright pink flowers that add brightness to landscapes in early summer. Flos-cuculi means “flower of the cuckoo,” referring to the shared time of year when cuckoos are first heard and ragged robin is first seen.

Although its numbers have declined in some of its native ranges, such as in Britain, ragged robin has become introduced and somewhat naturalized in parts of the United States and Canada. This is a tough plant and is generally easy to grow provided it has the benefit of growing in moist soil.

Facts, Benefits & Uses of Ragged Robin

swallowtail butterfly on a ragged robin flower
Ragged robin is a valuable nectar source for pollinators, such as this swallowtail butterfly. Photo by Nick Goodrum / CC BY-SA 2.0

Ragged robin’s beautiful pink flowers attract pollinators such as long-tongued bees, butterflies, and hummingbirds. Deer and rabbits are not fond of this plant, and are unlikely to eat it. Ragged robin is considered easy to grow, and self-seeds readily. This plant has developed a method to deter small insects such as ants from climbing it: a series of small, downward-pointing hairs make it difficult for ants to pass through. Interestingly, ragged-robin is now being studied for its potential use as a source for medicine!


Additionally, ragged robin makes a valuable addition to bogs as it prefers waterlogged locations and does just as well in acidic conditions as it does in neutral or more alkaline conditions. Their vivid flowers draw in pollinating insects, which in turn draw in birds, frogs, turtles, and a variety of other wildlife that all add to the biodiversity of bog habitats. If you have built or want to build your very own bog garden, ragged robin can bring these benefits to your backyard, along with these edible native bog plants.

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Ragged Robin Fact Sheet:
Herbaceous Perennial
USDA 3 – 9
Full sun to partial shade
June – August (Summer)
Height 30-60 cm (12-25 in.)
Seeds: just under surface; Mature plant: 10-15 cm (4-6 in.)
pH 4.0 – 8.0

Ragged Robin Growth, Hardiness & Climate

how to plant ragged robin
Ragged robin typically grows between 1 and 2 feet tall. Photo by Agnieszka Kwiecień, Nova, CC BY-SA 4.0

Ragged robin is easy to grow when provided with the proper conditions, including partial to full sun and moist or wet soil. This plant is fairly adaptable but will do best if it is not overcrowded by other plants, thus creating too much shade. Ragged robin is hardy in zones 3-9. It can survive above zone 9, but will require extra water and less sunlight so that it doesn’t get too dried out. This plant is a perennial and is able to survive cold winters.

This plant can grow from around one to two feet tall, and spreads by seed. It also can be propagated by division. Ragged robin plants produce beautiful bright pink blooms that generally make their appearances in June through August.

How to Plant Ragged Robin In Ponds

how to grow ragged robin in ponds
Ragged robin grows best in damp or saturated soils, but not in standing water. Photo by ceridwen / Ragged Robin (Lychnis flos-cuculi)

Ragged robin seeds are dependent on cold-stratification in order to grow, meaning that they require a period of cold weather in order to emerge from dormancy. The freezing and thawing of the soil scratches the seeds, which promotes growth once the ground is warm enough.

Gently press seeds just under the surface of the soil in late summer to early fall the year before you wish them to sprout. There is no need to water the seeds yet, as they will not germinate until spring arrives. However, be sure to keep the soil moist once your seeds do sprout. This method mimics the natural life cycle of ragged robin best: mature plants drop seeds at the end of summer, and they sprout the following spring.

If growing ragged robin from an already established plant, simply bury the roots up to the crown of the stem in rich soil. You can also gently pull established plants from the ground in autumn and carefully divide them if you wish. If you live outside of its native range, you may wish to plant ragged robin in pots to help control its growth, and deadhead the flowers before they go to seed to help prevent it from escaping into nearby natural areas.

How to Care For Ragged Robin

Ragged robin blooming in the sun
If provided with ample sun and moisture, ragged robin survives and grows easily. Photo by Caitriana Nicholson / CC BY-SA 2.0

Ragged robin is fairly low-maintenance and tends to be an easy plant to care for. This plant does best in moist, rich soil. As such, ragged robin will happily grow near the edges of a pond or in a bog garden, which can help to ensure it has consistent access to water. Ragged robin does need a good amount of sunshine, so be sure that other plants or structures are not providing too much shade. These plants are perennials, so expect to see them for several years in your garden or near your pond if you decide to grow them.

How to Winter Ragged Robin

Ragged robin is native to northern areas with cold winters, and as a result is able to survive frost and snow. In fact, it is important that this plant is grown in areas with cold winters because its seeds rely on cold stratification to sprout in the spring. There is no need for any special treatment to prepare ragged robin for winter when grown in their native hardiness zones. Outside of their native hardiness zone, ragged robin may become an annual plant rather than a perennial, which could actually be a boon as this will help deter it from spreading into other habitats.

Is Ragged Robin Toxic, Poisonous or Invasive?

Ragged robin is native to Europe and parts of Asia but has also established itself in parts of North America. Although it is not an overly aggressive plant, it can have some invasive tendencies. Try to use plants native to your home region in your garden. If you are set on planting ragged robin but are concerned about it spreading, you can remove wilting flowers from the plant before they turn to seed.

The roots of ragged robin contain saponin, which humans have used at times as a soap substitute. Although it is not really a significant threat to humans, it can affect some animal species. Saponins are toxic to fish and have even been used in large quantities as fish poison. The saponins in ragged robin are released when the roots are crushed or cut, so be careful not to let crushed roots come in to contact with pond water containing fish!

Is Ragged Robin Edible? Will Fish Eat it?

Ragged robin isn’t considered to be edible, as it contains saponins. It does not have a significant history of being consumed by humans—not even deer or rabbits like to eat it!

Saponins, found in the roots of ragged robin, are toxic to fish. Since this is not an aquatic plant and doesn’t grow directly in the water, fish are unlikely to come into contact with ragged robin roots, but this is still something to keep in mind.

Where to Buy Ragged Robin & Seeds? (UK & US)

Ragged robin seeds and mature plants are readily available in nurseries or online outlets that sell to the plant’s native ranges, as well as locations such as North America where the plant has been introduced. Elsewhere, you’ll likely have to order it online or ask your local nursery to make a special order.

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