Cirsium rivulare Frosted Magic

Cirsium rivulare 'Frosted Magic' is a brand new variety of River Thistle presented in 2016 at the Chelsea Flower Show. This stunning, rustic 'thistle' with white flowers brings that unique, white brightness that was missing from these plants which are normally blue, purple, and violet. This perennial will thrive by the edge of a stream where it likes the humidity, in a meadow with heavy soil, or in a wild garden, gently swaying its large pompoms in the summer breeze. 

Cirsiums are thistles of the Asteraceae family. Cirsium rivulare is native to Switzerland and central Europe, where it grows in moist places like meadows and mountain marshes. It is very cold-resistant, adapted to wet or moist, clayey, and fertile soils.

The 'Frosted Magic' cultivar is a herbaceous perennial, distinguished from the species by its white flowers. At maturity, this river thistle will form a flowering clump, 1 to 1.20 m (3 to 4ft) in height, spreading through underground stems over 50 to 60 cm (20 to 24in) wide. It forms basal leaves and well-developed, sparsely leafy stems. The foliage is dark green, the leaves are widely cut, slightly hairy, and bordered by spines. Flowering takes place in July-August, at the tips of the stems with flower heads, grouped in 2 to 8 units. Each head can reach 3 cm (1in) in diameter and is composed of numerous small white flowers, loved by pollinating insects. The flowering is followed by small silky fruits called achenes, which can self-sow.

This is a particularly hardy perennial plant that can withstand very wet conditions and heavy soil, even waterlogged in winter, it just needs a sunny location. This easy going, tall and wild thistle adds a bit of variety to a dull meadow or the edge of a pond. It can be paired with willowherbs, Salvia uliginosa, purple centaureas, fluffy globeflowers, or the pink pompoms of Lychnis flos-cuculi Jenny. You can use it to for cut dried or fresh flowers which will prevent self-seeding and promote late-season flowering. This variety is not invasive.