Rosemary (Rosmarinus officinalis) is a perennial herb native to the Mediterranean region, where it thrives in warm, dry climates with well-draining soil and plenty of sunlight. Its natural habitat includes rocky hillsides and coastal areas, which means it is adapted to bright light, moderate humidity, and infrequent rainfall. These conditions are key to replicating its ideal growing environment indoors.
Rosemary requires at least 6–8 hours of direct sunlight daily to grow healthily. Indoors, this can be challenging, especially in winter. Place the plant near a south-facing window for maximum light exposure. If natural light is insufficient, supplement with full-spectrum grow lights positioned 6–12 inches above the plant for 12–14 hours a day. Without adequate light, rosemary will become leggy, weak, and prone to disease.
Rosemary prefers well-draining, slightly alkaline soil with a pH of 6.0–7.5. A mix of potting soil with added perlite, sand, or gravel improves drainage. Use a clay or terracotta pot with drainage holes to prevent root rot. Avoid overpotting; rosemary likes to be slightly root-bound. Repot every 1–2 years to refresh the soil and accommodate growth.
Overwatering is a common cause of indoor rosemary failure. Allow the top 1–2 inches of soil to dry between waterings, then water deeply until excess drains out. Reduce watering in winter when growth slows. Rosemary tolerates low humidity but may suffer in overly dry indoor air. Avoid misting; instead, place a tray of water near the plant or use a humidifier to maintain moderate humidity.
Rosemary grows best in temperatures of 60–75°F (15–24°C). It can tolerate brief dips to 40°F (4°C) but is sensitive to cold drafts and sudden temperature changes. Keep it away from heaters, air conditioners, and drafty windows. Good air circulation prevents fungal diseases, so ensure the plant isn’t crowded and occasionally run a fan on low nearby.
Fertilize rosemary sparingly—every 4–6 weeks during spring and summer with a balanced, half-strength liquid fertilizer. Avoid over-fertilizing, which can lead to weak growth. Regular pruning encourages bushiness and prevents woody, sparse stems. Trim back up to one-third of the plant in spring or early summer, and harvest sprigs as needed to promote new growth.
Indoor rosemary may face pests like spider mites, aphids, or whiteflies. Inspect leaves regularly and treat infestations with insecticidal soap or neem oil. Root rot from overwatering manifests as yellowing leaves and a foul smell—reduce watering and repot if necessary. Leggy growth indicates insufficient light; adjust placement or add grow lights.
While rosemary can live indoors year-round, it may gradually decline after 3–5 years due to limited root space and light. To prolong its life, consider rotating it outdoors in summer (if climate permits) or propagating cuttings to start new plants. With consistent care, indoor rosemary can thrive and provide fresh herbs for cooking year-round.
