Green alkanet
Also known as
Evergreen bugloss, Blue alkanet, Alkanet
Keep this plant’s care guide close at hand.
Get the appAbout Green alkanet
Pentaglottis sempervirens, commonly known as green alkanet, is a vigorous, evergreen perennial in the borage family (Boraginaceae). It forms dense clumps of coarse, bristly, heart- to lance-shaped leaves that persist through winter. In spring to early summer, upright stems to about 60–90 cm bear many small, five-petaled, gentian-blue flowers with a distinct white eye, reminiscent of forget-me-nots but on a larger, more robust plant. It thrives in moist, partially shaded sites and is valued for feeding early pollinators such as bees. Green alkanet spreads readily by self-seeding and has a deep, often blackish taproot, making established plants difficult to remove. It tolerates a range of soils, including heavier clays, and favors neutral to alkaline conditions. While excellent for naturalistic borders and woodland edges, it can become weedy if not managed. The bristly foliage may irritate sensitive skin, and ingestion is discouraged due to pyrrolizidine alkaloids found in many borage relatives. It is best suited to outdoor sites rather than containers or indoor culture.
Taxonomy
Properties & Requirements
How to care for Green alkanet
Water
Keep soil evenly moist, especially through spring growth and flowering. Water newly planted specimens weekly in dry spells, delivering a deep soak rather than frequent splashes. Once established, it tolerates short dry periods but performs best with consistent moisture; increase watering during hot, sunny conditions. In heavy shade and cool climates, rainfall often suffices. For containers, check moisture regularly and water when the top 2–3 cm of mix feels dry. Ensure good drainage to avoid waterlogging, which can lead to root stress.
Light
Thrives in partial shade (dappled or morning sun with afternoon shade). It tolerates full shade, flowering less but maintaining evergreen foliage. In cool, maritime climates it can handle more sun if soil stays moist; in hotter regions, avoid full midday sun to prevent wilting and leaf scorch. Aim for 2–5 hours of gentle light daily. Under dense shade, enrich soil and irrigate during dry spells to sustain growth and spring bloom.
Nutrients
Green alkanet generally requires little or no fertilizer in the ground. Excess nutrients can encourage overly vigorous growth and self-seeding. In garden beds, a light top-dressing of compost or well-rotted leaf mold in late winter or early spring improves soil structure and moisture retention without pushing lush, floppy growth. Container-grown specimens (uncommon but possible) benefit from a half-strength, balanced, slow-release or liquid feed once in early spring only. Avoid high-nitrogen fertilizers, and prioritize organic mulches to support steady, moderate growth.
Temperature
Fully hardy outdoors in temperate climates, typically USDA Zones 6–9. Plants withstand winter frosts to about −15 °C when rooted in the ground with a mulch layer. Best growth occurs in cool to mild conditions (10–25 °C). In heatwaves above 30 °C, provide extra water and afternoon shade to reduce stress and leaf scorch. Overwinter containers in a sheltered spot to prevent freeze-thaw damage to roots. No indoor culture is needed or recommended for this species.
