Skip to Content

Rosemary Leaves Turning Brown — 6 Most Common Reasons

Rosemary Leaves Turning Brown — 6 Most Common Reasons

I love my herb garden. It’s one of the first gardens I planted, and I really enjoy seeing the different herbs change as they bear flowers or ripen.

When I realized my rosemary leaves were turning brown, I instantly knew something was wrong.

Here are the reasons I identified why rosemary leaves are turning brown.

 

Rosemary Leaves Turning Brown

Rosemary leaves turn brown when overwatered. The softened stems and leaves are then susceptible to fungal diseases that can cause plant death. Overwatering can be the result of high rainfall, humidity, and excessive watering, all of which can cause waterlogged soil, drowning the roots and cause rot.

Rosemary Leaves Turning Brown
Rosemary Leaves Turning Brown

 

6 Common Reasons Rosemary Leaves Turn Brown

Rosemary leaves may be a slightly brown-greenish color when dried, but on the living plant, the leaves should be a deep green. Brown leaves aren’t normal.

The leaves of the rosemary plant can be slight brown-greenish when dried
The leaves of the rosemary plant can be slight brown-greenish when dried

Here are the reasons why rosemary bushes turn brown and what to do about it.

 

1. Root Rot

The most likely cause of brown leaves on a rosemary bush is root rot due to overwatering.

Since rosemary is a versatile Mediterranean plant, it is used to living in semi-arid conditions like on the islands of Greece.

Since rosemary plants are used to living in semi-arid places, overwatering them can lead to root rot, browning its leaves
Since rosemary plants are used to living in semi-arid places, overwatering them can lead to root rot, browning its leaves

While rosemary will grow in more water-rich environments, the plant requires well-draining soil to ensure root rot doesn’t set in.

 

How to Fix It

Root rot happens when the rosemary roots don’t have an adequate balance of air and water in the soil.

So, by reducing the amount of water your rosemary gets, you will improve this balance and help the plant dry out so root rot can’t take place.

To avoid root rot in your rosemary plant, reduce the water it gets to avoid browning of its leaves
To avoid root rot in your rosemary plant, reduce the water it gets to avoid browning of its leaves

 

2. Manual Overwatering

When you continuously water the soil, your rosemary bush will develop root rot.

The soil doesn’t drain fast enough to clear the excess water, causing a loss of vital nutrients from the plant as the cells are so swollen with water.

Since the cells can’t take in more water, they also can’t take in nutrients, so the plant starves and the root cells die, causing root rot.

 

How to Fix It

Fixing brown leaves due to manual overwatering is quite simple — stop watering your rosemary. Rosemary should only be watered once in two weeks if there has been no natural rainfall (for outdoor rosemary plants).

Before you water your rosemary bush, first check whether the soil is dry by sticking your finger in.

If you feel the soil is damp up to the first digit of your index finger, you shouldn’t water the rosemary. If the soil is dry, water the plant moderately and then wait two weeks before you check it again.

If you find that the soil of the rosemary plant is still damp, don't water it to avoid root rot which leads to leaf browning
If you find that the soil of the rosemary plant is still damp, don’t water it to avoid root rot which leads to leaf browning

 

3. High Rainfall Area

If you live in a high rainfall area, your rosemary may turn brown because of excessive precipitation.

If you live in an area receiving high precipitation, it can cause overwatering of your rosemary, leading to root rot and eventually leaf browning
If you live in an area receiving high precipitation, it can cause overwatering of your rosemary, leading to root rot and eventually leaf browning

While you can’t turn off the rain, you can protect your rosemary bush.

 

How to Fix It

Ensure your rosemary is planted in well-draining soil. If the soil is clay-based or becomes waterlogged easily, you can change the composition of the soil by mixing in sand or grit.

To increase the drainage of the soil where your rosemary is planted and avoid leaf browning, mix sand or grit with the soil
To increase the drainage of the soil where your rosemary is planted and avoid leaf browning, mix sand or grit with the soil

The drainage will increase, creating soil that won’t become waterlogged and cause root rot in your rosemary.

 

4. High Humidity

Should you live in an area where there is high humidity, your rosemary may also start to turn brown.

The damp air of your area may cause excessive moisture to deposit on the soil and plant, causing rot and opening the door to fungal infections.

 

How to Fix It

Ensure your rosemary is planted in a well-ventilated area. If you plant the rosemary in a pot, ensure the pot is placed in a semi-shady spot to help limit the dampness of high humidity.

If you plant rosemary in a pot, ensure that it is placed in a semi-shady spot to limit the dampness brought about by high humidity
If you plant rosemary in a pot, ensure that it is placed in a semi-shady spot to limit the dampness brought about by high humidity

Again, creating well-draining soil and not watering as frequently can help maintain an arid balance for your rosemary.

 

5. Winter Watering and Frost

While we may think of winter as being a dry time, it is also a time when plants grow less.

When you water your rosemary too frequently in winter, the soil will lock in the water, freezing the roots of the bush and causing damage that manifests as brown leaves.

 

How to Fix It

Frost can also burn the leaves of the rosemary plant, so you may need to provide frost covering for winter.

Remember that rosemary is not native to cold climate zones. It prefers mild temperature regions.

 

6. Fungal Disease

Rosemary may be vulnerable to fungal spores setting up colonies when the plant has suffered damage due to root rot.

When the leaves turn brown, there may also be a slightly white or gray powder on the plant, which is a clear sign of fungal disease such as powdery mildew.

 

How to Fix It

To address the problem of fungal disease turning the rosemary bush leaves brown, you need to spray the bush with a solution of weak soapy water or diluted vinegar.

If you find the leaves of your rosemary bush turning brown, spray them with diluted vinegar or weak soapy water to remove the fungus causing it
If you find the leaves of your rosemary bush turning brown, spray them with diluted vinegar or weak soapy water to remove the fungus causing it

Ensure you set the plant aside in a well-ventilated area and monitor the soil for signs of waterlogging.

 

Frequently Asked Questions about Rosemary Leaves Turning Brown

 

Should you prune away the leaves that have turned brown on a rosemary bush?

If the leaves are brown, dry, and crumbly under your fingers, you should cut away these leaves and stems. Since these sections are already dead, they only increase the risk of fungal infections.

 

How can I save my overwatered rosemary bush from dying?

If your rosemary bush is planted in a pot, set the pot aside and wait for the soil to dry out. Ensure the pot is then placed in a well-ventilated area with direct sunlight. Overwatered garden-planted rosemary bushes can be helped by potting the plant in a well-draining mix of potting mix and sand.


 

Conclusion On Why Rosemary Leaves Are Turning Brown

Rosemary leaves are turning brown if you overwater it. Since rosemary has a slightly dried-out appearance, it is easy to believe the plant needs extra water, but rosemary prefers dry soil, watering every two weeks, and an uncrowded and sunny place to grow.

Author Bio

Daniel Iseli

Taking care of houseplants and gardening are my greatest passions. I am transforming my apartment into an urban jungle and am growing veggies in my indoor and outdoor garden year-round.

Plantophiles Shop