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    Psephellus bellus (Centaurea bella)

    Psephellus bellus, previously known as Centaurea bella is commonly called Caucasian cornflower or Evergreen knapweed. This evergreen herbaceous plant forms a dense cushion of grey-green leaves and has long, thin stems with pretty lilac-pink flower heads that appear in the spring. 

    Being native to the Caucasus, it thrives in adverse climatic conditions with extreme temperatures and prolonged droughts. 

    Due to its allelopathic properties, it requires very little weeding maintenance.


    Quick Overview

    TYPE

    Type herbaceous

    HEIGHT & WIDTH

    Psephellus Bellus - Centaurea bella (Caucasian cornflower) height and width

    BLOOM TIME

    Psephellus bellus - Centaurea bella (Caucasian cornflower) bloom time

    SUNLIGHT

    full sun / semi shade

    HARDINESS

    hardiness (-15ºC / 5º F)

    DROUGHT TOLERANCE

    drought tolerance aprox 4 months

    ORIGIN

    origin Caucasus

    Caucasian cornflower scientific name

    • Botanical name: Psephellus bellus (se-FELL-us BELL-us)
    • Family: Asteraceae (a-stuh-RAY-see-ee)
    • Common name: Caucasian cornflower, Evergreen knapweed, Silver knapweed
    NameMeaning
    Psephellus
    bellusThe Latin word for beautiful.

    How to identify Psephellus bellus

    Psephellus bellus plant (Centaurea bella)

    Plant

    Psephellus bellus has quite a unique form. A cushion or mat-forming grey-green herbaceous perennial with long upright stems topped with large individual pink flowers forming an elegant silhouette.

    It is a great weed suppressor due to its allelopathic properties.

    After 2 to 5 years, the plant reaches its mature size:

    • The foliage height ranges from 10 to 15 cm (4 to 6 in).
    • The flower stem height varies from 20 to 30 ( 7 to 11 in) cm 
    • The width ranges from 30 to 40 cm  (11 to 15 in) or more.

    .

    Psephellus bellus stem (Centaurea bella)

    Stem

    The stems have imparipinnate leaves, i.e., opposite leaves along the stem with a terminal unpaired leaf at the tip of the stem.

    The flower stems are woolly, long and thin.

    Psephellus bellus leaf (Centaurea bella)

    Leaf

    The leaves have an elliptical shape and are grey-green with white-hairy undersides. They are evergreen and never seem to struggle, even in harsher winters and summers.

    .

    Psephellus bellus flower (centaurea bella)

    Flower

    The flowers are lilac-pink, composed of many small disk florets and large outer ray florets that form the most noticeable part of the flower. These outer rays are divided nearly to the base into narrow segments. 

    The flower head is hard and enclosed in a mass of overlapping bracts. The stalks are long and thin.

    In warmer climates, the flowers will appear after the end of winter and bloom until summer. In colder climates, they will appear later at the end of spring and during the summer.

    Psephellus bellus Usage

    Ornamental

    Psephellus bellus is a very attractive plant with its evergreen foliage forming a cushion shape and long stems topped with pretty flowers that emerge in succession during approximately four months.

    It can have many uses in a garden: as a ground cover, as an edging, or scattered around in a rock garden. 

    Due to its low water needs and hardiness, it is well suited for dry gardens in either warm or cold climates.

    Medicinal

    Psephellus bellus has strong antifungal properties. Studies have shown its antifungal effect on the following strains of fungi: Candida, Rhodotorula, Trichophyton, Microsporum, and Scopulariopsis.

    Biodiversity

    Psephellus bellus can be very useful to promote biodiversity in your garden because pollinators love its flowers.

    Butterflies and bees pollinate the flowers.

    How to plant and care for Psephellus bellus

    Psephellus bellus is a low-maintenance drought-tolerant and hardy plant.

    It requires almost no weeding due to its allelopathic properties.

    It likes well-drained soils but with some moisture. The soil should preferably be neutral to alkaline, although it can also do well in acidic soils.

    It is a very hardy plant that can tolerate temperatures down to -15ºc (5ºF) or more.  It is frost tolerant.

    Psephellus bellus prefers full sun but can tolerate partial shade, so when planting, choose a spot in your garden with these conditions.

    The best time to plant this perennial is at the beginning of spring for colder regions or the beginning of autumn for warmer regions.

    How to water Psephellus bellus

    Psephellus bellus is a drought-tolerant plant and does not like humid soils. Once established it no longer requires watering.

    During the first two years after planting, you will need to water the young plant every two to three weeks during the summer.  Allow the soil to dry out between watering.

    When watering it, you need to do it abundantly, giving the soil a generous soak so the water can penetrate deeply into the soil to allow the roots to grow deeply. 

    To preserve the soil´s moisture you should add mulch around your plant (but not too close to the base). Wood chips and gravel are good options for mulching. 

    How to prune Psephellus bellus

    Prune off the flower heads as they start to fade to prolong the flowering period.

    At the end of the flowering season, cut back the leaf stems to promote the production of new leaves.

    How to propagate Psephellus bellus

    Psephellus bellus can be propagated by division in autumn or by softwood cuttings in spring.

    The stems will root where they touch the soil, so the plant naturally propagates itself by a layering method.  This enables it to spread and form a nice groundcover.

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    Sources

    Sources of information used for this article

    Article from Backyard gardener

    Article from The Gardenist

    Article from NCBI