Plume thistle [Frosted Magic] Cirsium rivulare Frosted Magic = 'Lowcir' (PBR)

Water

Plume thistle requires consistent moisture, so water deeply once a week, ensuring that the equivalent of about 1 to 2 inches of rainfall reaches the plant. During hot or dry spells, increase watering to twice per week. Avoid shallow watering which can lead to weak root development. Use a soaker hose or drip irrigation to apply water directly to the soil, rather than overhead watering, which can lead to foliar diseases. Adjust the amount based on rainfall to avoid overwatering as plume thistle prefers well-drained soil and may suffer in prolonged soggy conditions.

Light

Plume thistle thrives best in full sun, which means it should get at least 6 hours of direct sunlight each day. The ideal spot for this plant would be in an open area without significant shade from buildings or larger plants. While it can tolerate some light afternoon shade, too much shade can result in leggy growth and reduced flowering.

Temperature

Plume thistle prefers a temperate climate and can withstand a wide range of temperatures, but it grows best when the daytime temperatures range between 60°F and 75°F. It can survive short periods of colder weather, down to about 20°F, and can tolerate heat up to about 85°F, but prolonged exposure to extremes could be detrimental to the plant.

Pruning

Plume thistle should be pruned to remove spent flowers, which encourages new blooms and prevents seed spread. The best time for pruning is late summer or early fall, after the plant has finished blooming. Deadheading throughout the blooming season can also promote a longer flowering period. Every few years, perform more significant pruning to cut back older growth and rejuvenate the plant.

Cleaning

As needed

Soil

The best soil mix for brook thistle (Cirsium rivulare 'Frosted Magic') is well-draining and fertile, with a good amount of organic matter like compost or well-rotted manure. The soil should be kept moist but not waterlogged. A pH range between 6.0 and 7.0 is optimal for this plant.

Repotting

Brook thistle generally does not require frequent repotting as it is often grown as a perennial in gardens. It can be divided every few years during its dormant period to rejuvenate the plant and prevent overcrowding. Repotting is more common when grown in containers, preferably every 2-3 years.

Humidity & Misting

Brook thistle appreciates an environment with moderate to high humidity levels. However, it is quite adaptable and can tolerate a range of humidity conditions as long as the soil moisture is adequately maintained. No specific humidity level is prescribed, but a natural outdoor environment or a non-arid room would suffice.

Suitable locations

• Indoor

  Ensure bright light, moist soil, and cool room temperatures.

• Outdoor

  Plant in full sun to partial shade and keep soil consistently moist.

• Hardiness zone

  4-9 USDA

Life cycle

Cirsium rivulare 'Frosted Magic', commonly known as plume thistle, begins its life cycle as seeds that germinate in spring when temperatures are favorable. The seedlings develop into rosettes of prickly leaves close to the ground, focusing on root development. As the plant matures, it elongates to form erect, leafy stems that can reach up to 1.2 meters in height, typically in its second growing season. From early to late summer, 'Frosted Magic' produces abundant fluffy, magenta or reddish-purple flower heads attractive to pollinators such as bees and butterflies. After pollination, these flowers set seed that can disperse around the surrounding area, ensuring the continuation of the species. In the winter, the above-ground parts of the plant die back, but the root system remains alive to regenerate new growth the following spring.

Propogation

• Propogation time

  Spring-summer

• The Cirsium rivulare 'Frosted Magic', commonly known as Plume Thistle, is typically propagated by seed. The most popular method of propagation for Plume Thistle is to sow seeds indoors before the last frost of spring, which usually translates to 6-8 weeks prior to the expected date of frost in your area. Fill small pots or a seed tray with a well-draining seed starting mix. Sow the seeds thinly on the surface and lightly cover with a thin layer of soil, as they require some light to germinate. Maintaining a consistent moisture level, the seeds will typically germinate in 2-3 weeks if kept at a temperature around 70°F (21°C). Once seedlings have developed a few true leaves and are big enough to handle, they can be transplanted into individual pots and later moved outdoors when the risk of frost has passed.