Rosemary
Salvia rosmarinus
Rosemary is a woody, aromatic perennial herb native to the Mediterranean. It thrives in poor, dry, well-drained soils and is drought-tolerant once established. In mild climates it can be harvested year-round. Waterlogged conditions are the most common cause of failure.
Terminology
Key facts
- Family
- Lamiaceae (Mints)
- Category
- Herb
- Height
- 60-120 cm depending on variety and age
- Soil type
- Poor to moderately fertile, well-drained, sandy or gritty soil
- Soil pH
- 6.0-8.0
- Sowing window
- Mar–May
- Sowing depth
- 5 mm
- Spacing
- 45-60 cm
- Watering
- low
- Frost sensitivity
- medium
- Harvest window
- Jan - Dec
- Storage
- Fresh sprigs in water or wrapped in damp paper; dried sprigs in airtight container
- Storage duration
- Fresh: 1-2 weeks; dried: 6-12 months
Soil
Preparation
- -Add horticultural grit to heavy soils to improve drainage - waterlogging is the main cause of plant death
- -Avoid rich soils or heavy feeding - this promotes soft growth that is more susceptible to frost damage
Sowing notes
- -Seed germination is slow and unreliable - cuttings are strongly preferred
- -If sowing from seed, surface sow or sow very shallowly and maintain warmth (18°C+)
- -Established pot-grown plants are the most practical starting point for most growers
Propagation
- -Take semi-ripe cuttings in summer (June-August) - 10 cm tip cuttings with lower leaves removed
- -Root in gritty, free-draining compost in a warm, bright spot
- -Overwinter young plants under glass in the first year in cold or wet climates
Harvest notes
- -Harvest by snipping young, soft stem tips - avoid cutting back into old woody growth
- -Harvest little and often to maintain a productive, bushy habit
- -Light trimming after flowering prevents the plant becoming leggy
Varieties
Issues & threats
Wilting
EnvironmentalPlants are drooping or losing vigour. Most commonly caused by water stress but can also indicate root damage, vascular disease, or heat scorch. Identifying the cause quickly is important as some causes are serious.
Poor germination
EnvironmentalSeeds are emerging unevenly or not at all. Usually caused by soil temperature being too low, seeds sown too deep, poor seed-to-soil contact, or old seed stock.
Damping off
Fungal diseasePythium spp. / Phytophthora spp.
Young seedlings collapse at or just below soil level, caused by fungal pathogens that thrive in overwatered, poorly ventilated growing conditions. Can spread rapidly through a seed tray.
Yellowing leaves
EnvironmentalLeaves are turning yellow, which can indicate a range of problems including nutrient deficiency, overwatering, disease, or natural senescence. Identifying whether the pattern is upper or lower leaves, whole leaves or between veins, is key to diagnosis.
Stunted growth
EnvironmentalPlants are significantly smaller or slower to develop than expected. May be caused by poor soil, nutrient deficiency, root restriction, compaction, pest damage to roots, or disease.
Slugs
PestSoft-bodied molluscs that feed on plant material at soil level, most active at night and in wet conditions. A persistent pressure throughout the growing season, especially damaging to seedlings and young transplants.
Chewing damage
PestGeneral chewing damage from an unidentified pest, leaving holes or missing leaf sections. May be caused by caterpillars, beetles, or other insects. Inspect at dusk to identify the culprit.
Sap-sucking pests
PestGeneral sap-feeding pest activity causing weakened or distorted growth. May be caused by aphids, whitefly, scale insects, or other sucking insects. Inspect leaf undersides and growing tips to identify the pest.