The flowers of the Caucasian crosswort shine in a delicate pink in summer. This is how you plant and care for the perennial.
Profile of Caucasian crosswort:
Scientific name: Phuopsis stylosa
Plant family: bedstraw family (Rubiaceae)
Other names: large-styled crosswort
Sowing time: spring
Planting time: spring
Flowering period: June to August
Location: sunny to partially shady
Soil quality: sandy to loamy, calcipholous, humus rich
These information are for temperate climate!
Use in: ground cover, embankments, individual position, group planting, dry stone walls, underplanting, natural garden, rock garden
Winter hardiness: hardy, USDA Plant Hardiness Zones: 5 (-26 °C / -15 °F)
Bee and insect friendly: Yes
Plant characteristics and classification of Caucasian crosswort
Plant order, origin and occurrence of Caucasian crosswort
The Caucasian crosswort or large-styled crosswort, botanically Phuopsis stylosa, is the only species of its genus. Like the woodruff (Galium odoratum) it belongs to the bedstraw family (Rubiaceae). Caucasian crosswort originates from the Caucasus, eastern Turkey and Iran and grows there on the edges of a wood, in light woods as well as in rocky areas. The close relationship between woodruff and the Caucasian crosswort is visually recognizable, but unlike woodruff, it is not edible, but also not poisonous. In the garden, the Caucasian crosswort is unfortunately quite rare, although the perennial has been well known and cultivated since the 1830s. In the right place, the plant is also an extremely vigorous and undemanding ground cover with striking pink flowers. Humid weather and especially after a rain shower, the plants exude a somewhat idiosyncratic, tart scent of coumarin.
Characteristics of Caucasian crosswort
The perennial, herbaceous plant forms soft, long shoots that stand or lie upright and whose length ranges from 15 to 30 centimeters. Roots are sometimes formed at the leaf nodes that come into contact with the ground. Over time, the loose clumps develop into larger, connected mats, which can suppress weakly growing neighboring plants as well as weeds.
The evergreen, small, narrow elliptical leaves of the Caucasian crosswort are arranged in whorls of six to nine around the stem. There are fine hairs on the edges of the leaves.
The striking bloom of the Caucasian crosswort consists of small star-shaped flowers that stand together in spheres and show color from June to August. They glow pinkish violet to pinkish red. The delicate styles protrude far out of the flowers, which is why the plant is often called the large-styled crosswort. Both the flowers and the leaves have a light scent.
Caucasian crosswort – cultivation and care
As in its natural habitats, Caucasian crosswort also grows in the garden in partially shady as well as very sunny places. Only in deep shade the plant will not really feel at home and will develop only in gaps. In general, however, the perennial is adaptable and quite undemanding.
A permeable, sandy to loamy and rather calcareous underground is ideal. The plant tolerates dryness in partially shady areas. The sunnier and warmer the location, the fresher the soil should be. The shoots rot on heavy clay and other soils that tend to waterlogging. In poorer soils, the plants develop less abundantly and rapidly than in good garden soils.
Depending on its use, plant the Caucasian crosswort either in small groups of 3 to 5 plants to make it stand out, or in a larger area if it is to serve as a ground cover. In the first case, the planting distance is about 30 centimeters (12 in), in the second you can plan up to nine specimens per square meter (10 sq ft).
Cutting back the leaf crown in early spring and immediately after flowering allows the clumps to sprout again and grow more compact.
The plants can be propagated by division in spring and sowing.
Diseases and pests
Snails and other pests leave the Caucasian crosswort alone. Also plant diseases are no problem. Only snow-free cold periods are a problem for it, the plants will freeze.
The Caucasian crosswort is hardy down to -26 °C / -15 °F.
Use in the garden
The Caucasian crosswort fits on the edge of perennial beds, on the top of walls and on the edge of a wood. Beautiful planting partners are at the same time flowering cranes bill like Caucasian crane’s-bill (Geranium ibericum) or purple cranesbill (Geranium x magnificum). On sunny open spaces, blue wild indigo (Baptisia australis) or meadow sage (Salvia pratensis) also do well. The tendency to mat-like growth makes the plant the ideal choice for underplanting in tricky places, such as under shrubs or on embankments.
The light pink wild form is usually found in the trade, in perennial nurseries above all the variety Phuopsis stylosa ‘Purpurglut’, which blooms especially abundantly in intense carmine pink and grows more reliably. The paler selection ‘Roseum’ is rarer.