Bog sage
Salvia uliginosa · Lamiaceae
📷 Louise Docker from sydney, Australia · CC BY 2.0
The gardener's calendar
Bog sage is in full bloom: enjoy it, watch watering in hot weather and let spent flowers feed pollinators before pruning.
ID card
- Scientific name
- Salvia uliginosa
- Family
- Lamiaceae
- Plant type
- Herbaceous perennial
- Foliage
- Deciduous to semi-evergreen
- Flowering
- August to October, sky-blue flowers
- Mature size
- 120 cm in height
- Hardiness
- Moderate (−5 to −10 °C)
- Origin
- South America (Argentina, Brazil)
✓ Taxonomy verifiedSource: AI estimate · hardiness: reliability medium.
Expert tips
The key tip
Salvia uliginosa loves sun and cool soil in season, but hates waterlogging in winter.
The common mistake
Letting it age without pruning gives bare stems and tall flowering that's less visible.
The pro's trick
After the first bloom, cut back spent stems to encourage an autumn flush.
Care
Exposure
Plant bog sage in full sun, where it receives at least 6 to 8 hours of daily sunlight. A south or west-facing exposure is ideal to encourage abundant flowering. It tolerates light shade but will flower less generously.
Watering
Keep the soil regularly moist, especially during the growing and flowering periods. Water deeply without creating waterlogging: the plant appreciates moisture but dreads stagnant water. In winter, reduce watering but don't let the soil dry out completely.
Soil
Choose rich, well-draining soil that is slightly acidic to neutral. Add compost or potting soil at planting time to enrich the substrate. Bog sage enjoys cool, slightly moist soil, which explains its common name.
Pruning and training
Cut back the plant in spring (March–April) to encourage vigorous branching and a compact shape. Remove faded stems and spent flowers regularly to extend the flowering period. In late autumn, cut dry stems down to ground level before winter.
Fertilizer
Apply balanced fertilizer in spring when new growth starts. During the flowering period (August to October), apply fertilizer slightly enriched in potassium every 3 to 4 weeks to support flower production.
Diseases and pests
Watch for powdery mildew in warm, humid weather: ensure good air circulation. Spider mites may appear in dry conditions. Overall, a well-maintained, well-ventilated plant resists common health problems well.
Did you know?
Salvia uliginosa owes its epithet 'uliginosa' to the Latin uligo, meaning marsh or moisture. Native to the subtropical regions of South America, it gradually established itself in European gardens during the twentieth century, where it captivates with its sky-blue flowers and rare late autumn flowering. It remains an excellent companion plant for enriching borders when most other perennials tire out.
Where to buy it
Plant in spring or early autumn, avoiding spells of intense heat. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, April, May, September.
Add this plant to my garden →Plants from the same family
- ThymeThymus vulgaris
- LavenderLavandula angustifolia
- SageSalvia officinalis
- BasilOcimum basilicum
- RosemarySalvia rosmarinus
- BugleAjuga reptans
Tips generated and checked by Viridia — adapt them to your local climate.