How to grow rosemary hedge
Overview
Rosemary (Salvia rosmarinus) is an evergreen shrub with aromatic needle-like leaves, valued as both a culinary herb and a formal or informal hedge. It is drought-tolerant once established and thrives in full sun with excellent drainage, making it ideal for low-maintenance gardens.
Varieties
- Tuscan Blue — Upright, vigorous grower with dark blue flowers and strong flavour; excellent for hedges in Australian gardens.
- Arp — Hardy, cold-tolerant variety with pale blue flowers; suits cooler inland areas and retains good flavour.
- Prostratus — Low-growing, trailing form ideal for ground cover or over walls; less suited for formal hedges but good for cascading.
- Blue Spires — Erect, dense growth with vivid blue flowers and highly aromatic leaves; a popular choice for hedge rows.
- Majorca Pink — Compact bush with attractive pink flowers and slightly softer flavour; adds ornamental value to hedges.
Soil Preparation
Rosemary thrives in sandy or loamy soils with excellent drainage and a pH of 6.0–7.5. Before planting, amend heavy clay with gypsum and coarse sand, or plant in raised beds. Add compost sparingly; too much organic matter can retain moisture. Conduct a soil test to adjust pH if needed.
Growing Guide
Plant rosemary in full sun in well-drained soil with a pH of 6.0–7.5. Space plants 30–60 cm apart for a dense hedge. Dig a hole twice the root ball width, backfill with native soil mixed with a little organic matter, and water in moderately. Avoid planting in clay or areas where water pools. For best establishment, plant in autumn or spring in temperate zones, and autumn in hot-summer climates.
Care
Feed in spring with a balanced slow-release fertiliser (e.g., 8-4-6). Prune lightly after flowering to maintain shape, remove dead wood, and encourage fresh growth. Apply a thin layer of mulch at least 10 cm from the stem base to retain moisture without causing collar rot. Replace plants every 5–8 years as they become woody and less productive.
Companion Planting
Rosemary pairs well with other Mediterranean herbs like lavender, sage, thyme, and oregano. It makes a good low edible hedge and can deter some pests when planted near brassicas and carrots. Avoid planting near moisture-loving plants that require frequent watering, as rosemary prefers dry conditions.
Common Pests & Risks
Scale insects can appear as brown bumps on stems; control with horticultural oil or neem oil. Root rot, caused by overwatering or poor drainage, is the most serious disease – ensure the soil is free-draining and avoid wet feet. Spider mites may occur in very dry conditions; hose foliage occasionally to discourage them.
Harvesting
Harvest sprigs by cutting stems as needed once the plant is established, typically after 3–6 months. For the best flavour, pick just before flowering. Regular harvest encourages bushier growth and prevents woodiness. Strip leaves from stems and use fresh, dried, or frozen.
In the Kitchen
Rosemary leaves are used fresh or dried to flavour roasted meats, vegetables, bread, and marinades. Strip leaves from woody stems before use; chop finely or steep whole. Leaves can be frozen in olive oil or dried for long-term storage. Avoid overusing as it can overpower dishes.
Troubleshooting
Yellow leaves: caused by overwatering or poor drainage; reduce watering and improve soil drainage. Brown leaf tips: often from salt buildup or dry air; flush soil occasionally and avoid fertilizer burn. Leggy growth: insufficient sunlight; move to a spot with at least 6 hours of direct sun. Root rot: heavy clay or constant moisture; replant in well-drained soil or raised bed. Sparse foliage: old woody plants; prune heavily or replace every 5–8 years.