Why Is My Rosemary Turning Brown

If you’re asking “why is my rosemary turning brown,” you’re not alone. This is a common frustration for gardeners, but the good news is that it’s often fixable. Rosemary is a tough herb, but it has specific needs. When those aren’t met, it sends a signal through browning needles, dry stems, or general decline.

Let’s look at the main reasons your plant might be struggling. We’ll go through each cause and give you clear solutions to bring your rosemary back to health.

Browning rosemary is a symptom, not a disease itself. It’s the plant’s way of telling you something in its environment is wrong. The key is to play detective and figure out which factor is the culprit. Often, it’s a combination of two things, like poor drainage and cold weather.

1. Overwatering and Root Rot

This is the number one cause of death for potted rosemary. In the ground, it’s less common unless the soil is very heavy. Rosemary is native to the dry, rocky hillsides of the Mediterranean. It thrives on neglect when it comes to water.

Its roots need to dry out between waterings. Constantly wet soil suffocates the roots, leading to root rot. The roots turn mushy and brown and can’t take up water or nutrients. Ironically, the first signs above ground look like underwatering: browning tips and needles that eventually drop.

Check the soil before watering. Stick your finger 2-3 inches into the soil. If it feels damp, wait.
Ensure pots have excellent drainage. Your pot must have drainage holes. Use a gritty, well-draining potting mix, not regular garden soil.
For garden plants, amend clay soil with gravel or coarse sand to improve drainage.
If root rot is suspected, gently remove the plant. Trim away any black, slimy roots and repot in fresh, dry, gritty mix. Water sparingly after.

2. Poor Drainage (Wet Feet)

This is a sibling problem to overwatering. You might not be watering too often, but if the soil or container holds water, the result is the same. Heavy, compacted, or clay-based soils are a major problem for rosemary.

Water pools around the roots, creating an anaerobic environment. The roots simply drown. This is especially problematic in winter when the plant’s water needs are lower and evaporation is slower.

For planting beds, raise the area or create a mound to improve runoff.
Mix in plenty of coarse material like perlite, small gravel, or sharp sand when planting.
Consider growing rosemary in a raised bed filled with a tailored, fast-draining soil mix.

3. Underwatering and Drought Stress

While rosemary is drought-tolerant, it’s not a cactus. Newly planted rosemary and potted plants, especially in full sun and heat, need regular water until established. A completely dried-out root ball will repel water, causing the plant to desiccate and turn brown from the roots up.

Potted rosemary dries out much faster than plants in the ground. During a heatwave, you might need to water a pot daily. The goal is to water deeply, then let it dry almost completely.

Water deeply and thoroughly until water runs out the drainage holes. This encourages deep roots.
Don’t just sprinkle the surface. For in-ground plants, a slow, deep soak is best.
Use a moisture meter if you’re unsure. It can help you learn your plant’s rhythm.

4. Cold Weather and Frost Damage

Most rosemary varieties are only hardy to about 20-30°F (-6 to -1°C). A sudden hard freeze or prolonged cold, wet winter can cause browning. The damage often appears on the outermost, newest growth first. Needles turn brown or grayish-brown.

Windy, cold conditions can also cause winter burn, where the plant loses more water through its leaves than the frozen roots can replace. Container plants are more vulnerable because their roots are less insulated.

Choose a hardy variety like ‘Arp’ or ‘Hill Hardy’ if you live in a cooler climate.
Mulch around the base of in-ground plants with gravel or bark to insulate roots.
Move potted plants to a protected location, like a garage or against a south-facing wall, during freezes.
Wait until spring to prune any brown, frost-damaged growth. It may protect the inner stems from further cold.

5. Fungal Diseases

Wet foliage and humid conditions invite fungal issues. Two common ones are:

Powdery Mildew: Appears as a white, powdery coating on leaves, which may then turn brown and crispy.
Botrytis (Grey Mold): Causes brown lesions and a fuzzy gray mold, often in cool, damp weather.

These fungi thrive when plants are crowded, lack air flow, or are watered from above. Overhead sprinklers are a common culprit, leaving the foliage wet for hours.

Always water at the base of the plant, keeping the foliage dry.
Ensure good spacing and air circulation around your rosemary.
Prune out any dense, inner growth to improve airflow within the plant.
Remove and dispose of severely infected branches. Avoid composting them.
As a last resort, use an organic fungicide like neem oil or a sulfur-based product, following label instructions carefully.

6. Pest Infestations

Rosemary is relatively pest-resistant, but it can be bothered by sap-sucking insects. Spider mites and aphids are the main offenders. They pierce the needles and suck out plant juices, causing stippling, yellowing, and eventual browning.

Spider mites are tiny and love hot, dry, dusty conditions. You might see fine webbing before you see the mites themselves. A bad infestation can quickly cause widespread browning.

Spray the plant with a strong jet of water from a hose to dislodge pests. Do this every few days.
For persistent problems, use insecticidal soap or neem oil, covering all leaf surfaces, especially the undersides.
Encourage beneficial insects like ladybugs, which eat aphids.

7. Nutrient Problems and Soil pH

Rosemary prefers lean, slightly acidic to neutral soil (pH 6.0-7.0). Too much fertilizer, especially high-nitrogen formulas, can cause weak, sappy growth that’s susceptible to browning and disease. It can also burn the roots.

Conversely, extremely poor soil or a pH that’s too high (alkaline) can lock up nutrients, causing deficiencies that lead to yellowing then browning.

Go easy on fertilizer. A light application of a balanced, organic fertilizer in early spring is usually plenty.
If you suspect a pH issue, a simple soil test kit can give you answers. You can lower pH with sulfur or use a fertilizer for acid-loving plants if needed.

8. Natural Aging and Inner Browning

Sometimes, a little browning is normal. As rosemary grows, the older, inner needles naturally turn brown and drop to make room for new growth. This is a slow process and shouldn’t cause concern if the outer tips are still green and healthy.

Regular light pruning helps prevent the plant from becoming too woody and leggy in the center. It encourages fresh, bushy growth from the base.

How to Prune Brown Rosemary

Pruning is essential for health and shape. Always use clean, sharp shears.

Identify the dead or brown stems. Scratch the bark with your fingernail. If it’s green underneath, the stem is still alive. If it’s brown and dry all the way through, it’s dead.
Prune dead stems back to the base or to a point where you find live growth.
For shaping and to encourage bushiness, never cut back into the old, leafless wood. Always make cuts in the green, leafy sections, just above a set of leaves.
The best time for major pruning is in spring, after the last frost. You can do light trimming for harvest throughout the growing season.

Reviving a Brown Rosemary Plant: A Step-by-Step Rescue Plan

Diagnose: Check all the factors above. Is the soil wet or bone dry? Are there signs of pests? Was there a recent frost?
Adjust Watering: Correct your watering schedule immediately based on your diagnosis. This is the most critical step.
Improve Drainage: If the plant is potted, consider repotting with fresh, gritty mix. For garden plants, aerate the soil around the roots carefully.
Prune Strategically: Remove all clearly dead, brittle brown stems. Go slowly, checking for green life as you go.
Relocate if Needed: If the plant is in a bad spot (too shady, too exposed), plan to move it in the cooler season.
Be Patient: Don’t expect overnight recovery. It may take weeks or even until next spring for new growth to appear. Resist the urge to over-fertilize.

FAQs About Brown Rosemary

Can brown rosemary turn green again?
No, the brown needles themselves will not turn green. However, if the stem is still alive, new green growth can emerge from it. You need to prune away the dead material to see this happen.

Should I cut off the brown parts?
Yes. Pruning dead and brown parts helps the plant focus its energy on healthy growth. It also improves air circulation, reducing the risk of fungal disease.

How often should I water my potted rosemary?
There’s no fixed schedule. It depends on pot size, weather, and sun exposure. The rule is to water deeply only when the top few inches of soil are completely dry. In winter, this might be once every two weeks or less.

Why is my rosemary turning brown after repotting?
This is likely transplant shock. The plant may also have been planted too deeply or in the wrong soil mix. Ensure it’s in well-draining soil, water it in well once, and then leave it to adjust. Keep it in partial shade for a few days if you can.

Is it better to grow rosemary in a pot or the ground?
In colder or wetter climates, a pot is often better. You can move it to shelter in winter and control the soil mix completely. In warm, dry climates with well-draining soil, the ground is excellent and allows it to grow larger.

Rosemary is a resilient plant. By understanding its Mediterranean origins—loving sun, good drainage, and not to much fuss—you can usually reverse the browning. Pay close attention to your watering habits and the weather, and your plant will likely reward you with its fragrant, healthy growth for years to come.