Plant Library

An index of the perennial plants grown and offered at Glenraven.

Calamintha nepeta ssp. nepeta

Calamintha nepeta ssp. nepeta

Calamint

10365768401207|Calamintha nepeta ssp. nepeta|Calamint|

A compact, neatly rounded perennial flowering steadily from mid-summer into autumn with pale mauve-blue flowers. The aromatic foliage releases a mint-like scent when handled, while the plant itself remains well-behaved, neither running nor self-seeding. Particularly effective at the front of the border or planted in groups, where its long season and calm structure carry plantings through late summer.

|July–Oct|light blue|green|rounded mound|front of borders; mixed plantings; mass plantings; herb gardens|35|50|full sun|average to dry|well-drained garden soils|low|forms neat, rounded mounds that flower continuously from mid-summer into autumn; foliage releases a strong mint-like scent when brushed; attractive to bees; does not run or self-seed; performs well in larger groupings and alongside ornamental grasses|yes|mid-summer through autumn flowering|pollinators|5||rounded habit; long flowering season; aromatic foliage; excellent for bees; non-running; non-self-seeding; culinary use; PPA|//glenravennursery.com/cdn/shop/files/4FC15EA7-2C23-47F8-8EAE-D43B4728EC69_1_105_c.jpg?v=1767478632&width=800|
Calamintha nepeta ssp. nepeta ‘White Cloud Strain’

Calamintha nepeta ssp. nepeta ‘White Cloud Strain’

Calamintha nepeta ssp. nepeta ‘White Cloud Strain’

10365768433975|Calamintha nepeta ssp. nepeta ‘White Cloud Strain’|Calamintha nepeta ssp. nepeta ‘White Cloud Strain’|

A white-flowered form of calamint with a slightly looser, more open habit than the species. Flowering steadily from mid-summer into autumn, it maintains the same long season of bloom while tolerating a little shade. Light self-seeding can occur, but the plant remains easy to live with and effective at the front of the border or in mixed plantings.

|July–Oct|white|green|rounded mound|front of borders; mixed plantings; mass plantings; herb gardens|35|50|full sun to part shade|average to dry|well-drained garden soils|low|more open and slightly looser in habit than the species form; tolerates part sun; lightly self-seeds; flowers continuously through the season |yes|mid-summer through autumn flowering|pollinators|4||white flowers; open habit; long flowering season; aromatic foliage; tolerant of part sun; light self-seeding|//glenravennursery.com/cdn/shop/files/calamintha_nepeta_white_cloud.jpg?v=1767550982&width=800|
Campanula poscharskyana ‘E.H. Frost’

Campanula poscharskyana ‘E.H. Frost’

Trailing Bellflower

10365768532279|Campanula poscharskyana ‘E.H. Frost’|Trailing Bellflower|

A trailing bellflower producing small white flowers lightly flushed with blue from early summer into autumn. The flexible stems weave easily through neighbouring plants or spill over walls and edges, creating a soft, informal effect. Best used where its spreading habit can be accommodated and guided rather than constrained.

|June–Sept|white|green|trailing groundcover|rock gardens; walls; weaving through borders; groundcover|20|60|full sun to part shade|average|moisture-retentive; well-drained garden soils|low|small white bellflowers flushed with blue, deepening toward the centre; trailing stems are particularly effective spilling over walls or threading through neighbouring plants; more expansive in habit than clump-forming selections |moderate|early summer through early autumn flowering|pollinators|3||trailing habit; white flowers with blue flush; long flowering season; effective groundcover|//glenravennursery.com/cdn/shop/files/placeholder_portrait.png?v=1766878564&width=800|
Caryopteris divaricata

Caryopteris divaricata

Bluebeard

10365768565047|Caryopteris divaricata|Bluebeard|

A herbaceous caryopteris valued for its late-summer blue flowers and upright habit. Caryopteris divaricata comes into flower as the season turns, adding colour and structure when earlier plantings are beginning to fade. Best grown in full sun with good drainage, it is cut back in spring as new growth emerges and integrates easily into mixed borders.

|Aug–Sept|blue|green|upright clump|perennial borders; mixed plantings; late-season interest|120|80|full sun|average|well-drained garden soils|low|a herbaceous caryopteris flowering later than most perennials; foliage is aromatic when brushed; cut back in spring as new growth begins; sometimes listed under the older name Caryopteris divaricatus|moderate|late summer flowering|pollinators|5||upright habit; late-season flowering; aromatic foliage; clear blue flowers|//glenravennursery.com/cdn/shop/files/placeholder_portrait.png?v=1766878564&width=800|
Centaurea atropurpurea

Centaurea atropurpurea

Centaurea

10365768630583|Centaurea atropurpurea|Centaurea|

A tall, clump-forming centaurea with sturdy flowering stems held above finely divided foliage. Dark red, thistle-like flowers appear in early summer, emerging from neatly formed buds and giving the plant a strong vertical accent. Native to rocky slopes of the western Balkans, it is best suited to open, sunny sites with good drainage, where it remains contained rather than spreading.

|June–July|red|green|upright clump|perennial borders; dry gardens; gravelly slopes; naturalistic plantings|120|60|full sun|average to dry|well-drained; rocky or gravelly soils|low|a Balkan species forming strictly clumping plants; tall, sturdy stems rise above finely divided foliage; dark brownish-red thistle-like flowers emerge from well-shaped buds; suited to open, sunny positions |moderate|early summer flowering|pollinators|4||upright habit; clump-forming; dark red thistle-like flowers; strong vertical presence|//glenravennursery.com/cdn/shop/files/placeholder_portrait.png?v=1766878564&width=800|
Centaurea hypoleuca ‘John Coutts’

Centaurea hypoleuca ‘John Coutts’

Centaurea

10365768663351|Centaurea hypoleuca ‘John Coutts’|Centaurea|

A bushy, clump-forming centaurea with bright pink flowers held above grey-green foliage in late spring and early summer. When deadheaded promptly, ‘John Coutts’ produces a second flush later in the season, extending its presence well into late summer. Best grown in full sun on lean, well-drained soils, where its stems remain upright and the plant holds a tidy shape.

|May–June & Aug–Sept|pink|grey-green|bushy clump|perennial borders; mixed borders; sunny plantings|50|60|full sun|average to dry|lean, well-drained soils|low to moderate|good-sized pink cornflowers with a pale centre flower for several weeks in spring and early summer; prompt deadheading encourages a second flush later in the season; performs best and holds its shape in lean soils and full sun |moderate|spring and late-summer flowering|pollinators|4||bright pink flowers; bushy clump; repeat flowering with deadheading; grey-green foliage|//glenravennursery.com/cdn/shop/files/D1024A64-3B0E-422D-A710-F244409F3935_1_102_o.jpg?v=1767570072&width=800|
Centaurea orientalis

Centaurea orientalis

Centaurea

10365768696119|Centaurea orientalis|Centaurea|

A clump-forming centaurea with narrow, dark green foliage and softly coloured flowers held on branched, upright stems. Pale yellow blooms emerge from honey-toned, papery bracts through summer, giving the plant a light, dry-garden character. Native to the Balkan steppes, it has proven reliable over many seasons and remains well contained, making it an easy choice for sunny borders.

|June–Aug|yellow|dark green|upright clump|sunny borders; mixed perennial plantings; open sites|70|45|full sun|average|well-drained garden soils|low|a Balkan species native to steppe conditions; forms neat clumps with narrow leaves; sturdy stems branch toward the tips, carrying multiple papery bracts from which pale yellow flowers emerge;|moderate|summer flowering|pollinators|5||pale yellow flowers; clump-forming; branched flowering stems; well-behaved habit|//glenravennursery.com/cdn/shop/files/placeholder_portrait.png?v=1766878564&width=800|
Centaurea pulchra ‘Major’

Centaurea pulchra ‘Major’

Centaurea

10365768728887|Centaurea pulchra ‘Major’|Centaurea|

A tall, airy centaurea with finely divided, grey-green foliage and soft pink, thistle-like flowers held on slender stems in early summer. ‘Major’ brings a light, open quality to borders, sitting comfortably among grasses and other perennials. Best grown in full sun with good drainage, where its relaxed habit reads as intentional rather than loose.

|June–July|pink|grey-green|open clump|perennial borders; naturalistic plantings; meadow-style borders|120|60|full sun|average|well-drained garden soils|low|a taller, more open selection of Centaurea pulchra with finely cut foliage and softly coloured flowers; valued for its light structure rather than density; stems may benefit from support in richer soils|moderate|early summer flowering; light seedhead structure|pollinators|4||Centaurea|//glenravennursery.com/cdn/shop/files/placeholder_portrait.png?v=1766878564&width=800|