How to grow salvia
Overview
Salvia splendens, commonly known as scarlet sage, is a tender herbaceous perennial grown for its vivid red, tubular flowers and compact growth. It is typically treated as an annual in Australian gardens, providing bold colour from spring through autumn.
Varieties
- Salvia splendens 'Red Arrow' — Compact, early-flowering variety with intense red blooms, ideal for mass bedding in Australian gardens.
- Salvia splendens 'Vista Red' — Dwarf, heat-tolerant selection reaching 25 cm, perfect for pots and borders.
- Salvia splendens 'Sizzler' — Mixed-colour series with red, purple, and white flowers, bred for uniform performance in warm climates.
Soil Preparation
Salvia prefers a free-draining loam or sandy soil with a pH between 6.0 and 7.0. Before planting, incorporate well-rotted compost or aged manure at a rate of 2–3 kg per square metre. Avoid heavy clay unless improved with gypsum and organic matter.
Growing Guide
Plant salvia in a position that receives at least 6 hours of full sun daily, with well-drained soil of moderate fertility. Space plants 25–30 cm apart to allow good air circulation. Water at the base to avoid wetting foliage, and apply a thin layer of organic mulch to keep roots cool. For best results, plant out after the last frost in temperate zones, or during the dry season in tropical areas.
Sowing
Sow seeds 3 mm deep in seed-raising mix, keeping moist at 20–25°C. Germination takes 10–14 days. Transplant seedlings when 10 cm tall, spacing 25–30 cm apart. Direct sowing is possible in warm soil after frost risk has passed.
Care
Feed with a balanced liquid fertiliser every 4–6 weeks during active growth. Deadhead spent blooms regularly to encourage continuous flowering. Cut back by one-third in late summer to refresh growth and prevent legginess.
Companion Planting
Salvia pairs well with roses, ornamental grasses, and purple-leaved plants like Heuchera. Avoid planting near brassicas, as salvia may attract pests that also target these crops.
Common Pests & Risks
Aphids and whitefly can cluster on new growth; spray with a strong jet of water or use insecticidal soap. Spider mites may appear in hot, dry weather; increase humidity around the plant and apply neem oil if needed.
Troubleshooting
Yellow leaves: overwatering or poor drainage; reduce watering and improve soil. Brown leaf edges: low humidity or salt buildup; mist leaves and flush soil. Leggy growth: insufficient light; move to full sun. Stunted plants: root-bound in pots; repot into larger container. Powdery mildew: poor air circulation; space plants wider and avoid overhead watering.