Rosmarinus officinalis 'Prostratus' (Prostrate Rosemary)
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Rosmarinus officinalis 'Prostratus' (Prostrate Rosemary)
Contents
Introduction & History
Prostrate Rosemary is the ground-hugging form of the Mediterranean classic, cascading over walls, spilling from containers, and carpeting sunny banks with its aromatic, needle-like foliage. While sharing the same intense, resinous flavour as upright rosemary, its trailing habit opens entirely different design possibilities — from living mulch to dramatic spillover in raised beds and terrace gardens.
History & Origin
A naturally occurring growth form of rosemary (now reclassified as Salvia rosmarinus) found along rocky Mediterranean coastal cliffs, where plants cascade down limestone faces. Selected and propagated for ornamental and culinary use. The prostrate habit was first documented by botanists studying wild populations on the Balearic Islands and along the French and Italian Riviera.
Botanical Description
Evergreen, woody sub-shrub growing only 15–30 cm tall but spreading 90–150 cm wide. Narrow, needle-like leaves are dark green above and silvery-white beneath, highly aromatic when brushed. Light blue to lavender flowers appear in late winter to spring along the trailing stems. The habit is distinctly prostrate, with stems that root where they touch the ground.
Stem: Square (quadrangular) — diagnostic for Lamiaceae • Leaves: Opposite, decussate arrangement • Height: 30 cm at maturity • Spread: 120 cm • Foliage: dark green • Flowers: blue (spring)
Planting & Cultivation
Plant nursery-grown specimens in spring or autumn, spacing 60–90 cm apart for ground cover (they spread to fill gaps within 2 years). Set the crown slightly above soil level to prevent rot. Excellent at the top of retaining walls where it can cascade downward. In raised beds, position at edges for spillover effect. Can also be planted as a living mulch beneath taller Mediterranean shrubs.
| Sun exposure | Full Sun |
| Soil pH | 6.0-7.0 |
| Spacing | 120 cm |
| Seed depth | 3–6 mm (surface-sow if light-dependent germinator) |
| Water needs | Low |
| Soil type | Well-drained, humus-rich loam; add perlite or grit for drainage |
Cultivation Details
Full sun and extremely well-drained soil are essential — this is a Mediterranean cliff-dweller that rots in wet conditions. Add grit or perlite to heavy soils. Never mulch against the stems. Minimal fertilising — lean soil produces the most aromatic foliage. Trim back after flowering to maintain density and prevent woody bare centres. Tolerates drought, salt spray, and poor soil.
Climate & Hardiness
Hardy to about −10°C (USDA zones 8–11). Less cold-hardy than some upright varieties. In zone 7, plant against a warm south-facing wall with excellent drainage. In colder zones, grow in containers and overwinter indoors or in a cold greenhouse. Handles heat and drought beautifully. Intolerant of wet winters — good drainage is more critical than cold hardiness.
USDA zones: 8-10
Minimum temperature: -7°C
Drought tolerance: Yes — established plants tolerate dry spells
Seasonal Care
Spring: light trim after flowering to shape; take cuttings for propagation. Summer: no watering needed once established except in containers. Autumn: final trim before winter; ensure drainage is adequate. Winter: protect from cold wet rather than cold dry — cover with cloches in marginal zones. In zones 9–11, flowering may begin in late winter.
Propagation
By semi-hardwood cuttings in late spring or summer (10–15 cm tip cuttings, strip lower leaves, root in gritty compost). Layering is effortless — trailing stems often root where they contact soil, and can be severed and transplanted. Does not come true from seed (named cultivars must be propagated vegetatively). Cuttings root in 4–6 weeks.
| Method | Success rate | Time | Notes |
|---|---|---|---|
| Stem cuttings | 70–90% | 2—4 weeks | Softwood in spring, semi-ripe in summer; 8–12 cm |
| Division | 95%+ | Immediate | Split established clumps in spring or autumn |
| Seed | 50–80% | 14–28 days | Some require cold stratification; germination variable |
| Layering | 80–90% | 6–12 weeks | Pin low branch to soil; sever when rooted |
Diseases & Pests
Root rot in wet soil is the primary killer. Rosemary beetle (Chrysolina americana) can defoliate plants — hand-pick the metallic-striped adults and larvae. Spider mites in hot, dry indoor conditions. Powdery mildew in humid areas with poor air circulation. Generally very trouble-free in the right (dry, sunny) conditions.
Culinary Uses
Identical culinary uses to upright rosemary — lamb, roast chicken, focaccia, potatoes, olive oil infusions. The smaller leaves and trailing stems are particularly attractive as garnish. Excellent for rosemary-infused oils and vinegars. Strip leaves from the woody stems before adding to dishes, or use entire sprigs as aromatic skewers for grilled meats. Pairs with garlic, lemon, olive oil, and thyme.
| Category | Pairing suggestions |
|---|---|
| Red meat | Lamb, beef, venison, pork |
| Roast vegetables | Potatoes, root vegetables, squash |
| Bread | Focaccia, herb bread, crackers |
| Oils | Infused olive oil, compound butter |
Medicinal & Aromatherapy
Same properties as upright rosemary — contains rosmarinic acid, carnosic acid, and 1,8-cineole (eucalyptol). Traditionally used to improve concentration and memory. The essential oil is used in aromatherapy for mental clarity and circulation. Rosemary tea (steep fresh sprigs 5 minutes) is a traditional digestive aid and headache remedy across Mediterranean cultures.
| Compound | Properties |
|---|---|
| camphor | penetrating, cooling |
| 1,8-cineole | eucalyptus-like |
| carnosic acid | potent antioxidant |
| ursolic acid | anti-inflammatory triterpene |
| rosmarinic acid | antioxidant polyphenol |
Container & Companion Growing
Container Growing
Outstanding in hanging baskets, window boxes, and tall pots where it can cascade over the edges. Use a very well-draining potting mix (add 30% perlite or grit). Unglazed terracotta pots are ideal — they breathe and dry quickly. Water only when the top 3 cm of soil is dry. Feed sparingly — once or twice in the growing season. Bring indoors before frost in cold zones.
• Minimum pot size: 30–40 cm Ø, 15 L+
• Deep taproot; repot every 2–3 years
• Use free-draining potting compost with 20–30% perlite or grit
• Ensure drainage holes; stand on pot feet to prevent waterlogging
• Feed with dilute liquid fertiliser (half-strength) every 2–3 weeks in growing season
Companion Planting
Excellent companion for other Mediterranean herbs: thyme, oregano, sage, and lavender. Plant at the edges of raised Mediterranean herb gardens. The aromatic foliage may deter some pest insects. Cascading over walls, it pairs beautifully with upright santolina, artemisia, and cistus above.
| ✓ Good companions | Beans, Brassicas, Carrots, Strawberries |
| ✗ Avoid planting with | Cucumber, Fennel |
Common Mistakes to Avoid
Planting in wet, heavy clay — guaranteed death. Overwatering, especially in winter. Planting at the back of a border where the trailing habit is invisible — position at edges, on walls, or in elevated containers. Hard-pruning into old wood (rosemary doesn't regenerate from bare stems). Expecting cold hardiness beyond zone 8 without protection.
Harvesting & Preservation
Harvest sprigs year-round by snipping trailing stem tips. Prostrate rosemary has the same flavour intensity as upright forms. The low habit makes harvesting easy — reach down and clip. Dries beautifully: hang small bundles in a warm, dry spot for 1–2 weeks. Also freezes well in olive oil or butter. Sprigs keep fresh in the refrigerator for 2 weeks.
• Time of day: Early morning, after dew has evaporated but before intense midday heat volatilises essential oils
• Growth stage: Just before flowering, when essential oil concentration peaks. Once flowers open, the plant redirects energy from leaf production
• Season: Year-Round
• Part harvested: Leaves
• Harvest rule: Never remove more than ⅓ of the plant at once; this ensures continued vigorous regrowth
• Technique: Cut stems cleanly above a leaf node with sharp scissors or secateurs. Tearing damages tissue and invites disease
| Method | Process | Shelf life | Best for |
|---|---|---|---|
| Air drying | Tie bundles, hang upside down in warm, dark, airy space | 6–12 months | Most herbs |
| Oven / dehydrator | Spread on trays, 35–45°C until crisp | 6–12 months | Fleshy-leaved herbs |
| Freezing (whole) | Blanch 5s, ice bath, pat dry, freeze flat on tray | 6 months | Basil, chives, parsley |
| Freezing (oil cubes) | Chop fine, pack into ice cube tray, cover with olive oil | 6 months | Any culinary herb |
| Herb salt | Layer herb and coarse salt 1:4, dry and grind | 12+ months | Rosemary, thyme, sage |
| Infused vinegar | Pack jar, cover with warm vinegar, steep 2–4 weeks | 6 months | Tarragon, dill, basil |
| Infused oil | Fill jar with dried herb, cover with oil, steep 4–6 weeks | 3–6 months | Rosemary, thyme, chilli |
Frequently Asked Questions
How wide will Prostrate Rosemary spread?
A single plant typically spreads 90–150 cm. Space 60–90 cm apart for continuous ground cover within 2 seasons. It grows wider than tall, reaching only 15–30 cm high.
Can I use Prostrate Rosemary in cooking?
Absolutely — it has the same flavour as upright rosemary. The only difference is the growth habit. Harvest sprigs freely for any rosemary recipe.
Will it survive in a cold climate?
Prostrate Rosemary is hardy to about −10°C (zone 8). In colder zones, grow in containers and bring indoors or into a cold greenhouse for winter. Good drainage is more critical than cold protection.
Seasonal Care Calendar
🌱 Spring (Mar–May)
Water: Moderate
Feeding: Light feeding
☀️ Summer (Jun–Aug)
Water: Light
Feeding: No feeding
🍂 Autumn (Sep–Nov)
Water: Light
Feeding: No feeding
❄️ Winter (Dec–Feb)
Water: Light
Feeding: No feeding
A ground-hugging, cascading form of rosemary growing just 15–30 cm tall but spreading 90–150 cm. Same intense flavour as upright rosemary. Ideal for walls, hanging baskets, and raised bed edges. Requires full sun and excellent drainage. Hardy to −10°C (zones 8–11).
Quick Reference: Rosmarinus officinalis 'Prostratus'
Key Principles: Right location, well-drained soil, regular harvesting to promote growth, and appropriate winter protection for tender species.