Why Is My Rosemary Turning Yellow?

Yellowing rosemary leaves usually signal one of three issues — overwatering, poor drainage, or nutrient imbalance. Because rosemary is a drought-tolerant Mediterranean herb, too much moisture or fertiliser often does more harm than good. This CompleteGrow troubleshooting guide explains why yellow leaves appear and how to restore deep, fragrant green growth quickly.

1. Overwatering & Root Rot

Most common cause: Constantly damp soil suffocates roots, causing yellow, limp foliage.
Fix: Let the top 2–3 cm dry between waterings. Ensure pots have large drainage holes.
Soil reset: Mix two parts premium potting mix with one part coarse sand and perlite for aeration.

2. Lack of Sunlight

Rosemary needs 6–8 hours of direct sun each day to photosynthesise effectively.
Insufficient light produces weak, yellow-green leaves and leggy stems.
Move pots outdoors or near a bright north-facing window to revive colour.

3. Nutrient Deficiency

While rosemary grows in lean soil, complete neglect can still trigger yellowing — especially in pots where nutrients wash out. The most frequent deficiency is nitrogen, followed by magnesium or iron.

Apply a light, balanced fertiliser every 2–3 weeks. Over-correcting with high nitrogen blends makes foliage soft and aroma weak.

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Restoring Green, Healthy Rosemary

Check the Roots

Gently remove the plant from its pot. Healthy roots are firm and off-white; rotted roots are brown or slimy.
Trim away damaged roots with clean scissors and replant into dry, aerated soil.

Adjust Your Watering Routine

Water deeply, but only when the top soil layer is dry.
Empty saucers under pots — stagnant water quickly triggers rot.
During cool months, cut watering frequency in half; rosemary is semi-dormant in winter.

Feed Lightly, Consistently

For container plants, nutrients flush out faster. Feed with a balanced liquid such as CompleteGrow All Purpose NPK 20-20-20 every 2 weeks at 5 mL per 2 L of water. This keeps colour even and prevents stress-related yellowing.

Pro Tip: Alternate between fertiliser water and plain water sessions. This prevents salt buildup — a hidden cause of leaf burn and yellowing in container herbs.

Light, Airflow & Placement

Provide full sun exposure or supplement with LED grow lights indoors.
Keep airflow steady; stagnant air promotes fungal leaf spots.
Rotate pots weekly for uniform growth and even leaf tone.

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FAQs About Yellow Rosemary Leaves

Does yellow rosemary recover?
Yes — trim yellow leaves, improve drainage, and resume light fertilising. New shoots will appear within 2–3 weeks under proper light.

Can over-fertilising cause yellow leaves?
Absolutely. Heavy feeding burns roots and disrupts nutrient balance. Use small, consistent doses instead.

Is tap water safe for rosemary?
If your water is hard or alkaline, add a small pinch of citric acid per 2 L to balance pH to around 6.5.

Why do bottom leaves yellow first?
That’s usually nutrient leaching in containers or overwatering. Refresh the soil and apply a balanced fertiliser fortnightly.

CompleteGrow Recommendation

Use CompleteGrow All Purpose Liquid NPK 20-20-20 every 2 weeks during active growth to keep rosemary foliage deep green, aromatic, and resistant to yellowing. Its precise micronutrient blend corrects deficiencies while preventing soft, overfed growth.