How to grow flax lily
Overview
Flax lily (Dianella caerulea) is a clumping, grass-like perennial grown for its strappy foliage and soft blue flowers followed by edible blue berries. It provides texture and movement in shaded borders and under trees, and is highly drought-tolerant once established.
Varieties
- Dianella caerulea 'Little Jess' — Compact, 30 cm tall, ideal for small gardens and borders.
- Dianella caerulea 'Breeze' — Fine, arching foliage; good for mass planting and erosion control.
- Dianella caerulea 'Cassa Blue' — Blue-grey foliage, very drought-tolerant, popular in native landscapes.
Soil Preparation
Prefers slightly acidic to neutral soil (pH 5.5–7.0). Improve drainage in heavy soils with coarse sand or decomposed granite. Add well-rotted compost or leaf mould before planting to boost organic matter.
Growing Guide
Plant flax lily in well-drained soil enriched with organic matter, in part-shade to full shade. Space clumps 40–60 cm apart for a dense groundcover or 80 cm for individual specimens. Water regularly until established, then reduce to fortnightly deep soaks. Avoid heavy clay or waterlogged sites; improve drainage with coarse sand or gravel. Divide clumps every 3–4 years in early spring to maintain vigour and prevent overcrowding.
Care
Feed with a slow-release native fertiliser (low phosphorus) in early spring and autumn. Cut back old or damaged foliage to 10 cm in late winter to encourage fresh growth. Divide every 3–4 years to prevent centre dieback.
Companion Planting
Pair with ferns (e.g. Blechnum, Adiantum), liriope, and clivia for a layered shade garden. Avoid planting near aggressive grasses like mondo or buffalo that may outcompete. Good under native shrubs such as grevillea and callistemon.
Common Pests & Risks
Snails and slugs can chew new growth in damp conditions; use iron-based pellets or beer traps. Leaf spot (fungal) appears in humid weather—improve air circulation and avoid overhead watering. Remove infected leaves promptly.
Troubleshooting
Yellowing leaves: overwatering or poor drainage—reduce water and check soil. Brown leaf tips: dry air or underwatering—increase humidity or water. Leaf spot: fungal from wet foliage—space plants and avoid overhead watering. Stunted growth: nutrient deficiency—apply slow-release native fertiliser. Centre dieback: clump too old—divide every 3–4 years.