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Mint Plant Turning Brown, Purple, Yellow or Black – What To Do?

Nothing hurts more than witnessing your mint plant go from luscious green to yellow, black, brown, or purple. Even when properly cared for, the color of a mint plant might change. It’s because your mint plant’s color is changing for a variety of reasons. For years, I’ve been planting mint plants in my garden. Here’s a tutorial based on my own experience that explains why this problem exists and how to solve it.

A Mint Plant That Is Turning Yellow, Brown, Purple Or Black

There are a few frequent causes for mint plants to die; learn why yours is changing color and how to care for it.

What Causes the Purple Coloration of Mint Plants?

It’s distressing to see your well-established bush mint plant begin to turn purple. Mint leaves can become purple for a variety of reasons, but the most frequent is a phosphate deficit. Mint tris will become purple if the soil is deficient in phosphorus. When your plant isn’t getting enough hydration or has a pH level between 6-7, things get much worse.

A Suggestion

Cut the purple-leaved stems down to 1 inch above the ground as soon as possible. Pruning the diseased areas of the plant will assist to limit the spread of the illness.

Another solution to the problem is to use a phosphorus-rich fertilizer. Bone meal manure or compost is a phosphorus-rich organic fertilizer. You can make it yourself or purchase it from a local nursery.

Quick-release Another quick fix is phosphorus commercial fertilizer. 1 tablespoon of quick-release fertilizer should be applied to each plant.

To minimize over-fertilization, I prefer to use homemade organic fertilizer.

What Causes Mint Leaves to Turn Yellow?

Mint has always been a part of my garden and is one of my favorite herbs. Mint’s most prevalent problem, in my experience, is that its leaves become yellow. The presence of excessive moisture in the soil is the primary cause of this problem. Overwatering causes the plant roots to decay or choke, and the leaves become yellow.

Mint leaves become yellow due to too much shadow and low nitrogen levels in the soil. Underwatering and poor soil conditions, such as low nitrogen levels, can also cause this issue. Mint leaves become yellow due to rust fungus that thrives under high dampness, aphids, and harsh cold.

A Solution

It’s time to feed your mint plant with a nitrogen-rich fertilizer if you haven’t done so in a long time. I found that aged cow dung is the most effective fertilizer for treating yellow mint plants. It’s carbon and nitrogen-rich organic fertilizer. You can also use organic fish emulsion fertilizers or quick-release nitrogen fertilizers.

Plants should not be overwatered, and the moisture content in the soil should be checked on a regular basis. To improve the drainage of the soil, add well-rotted compost or dried leaves. If you have potted mint plants, make sure they have sufficient drainage on a regular basis. Excessive wetness is caused by clogged drainage.

Before the cold snap, cut down the golden foliage. The stems and roots will go dormant throughout the winter and reappear in the spring.

What Causes Mint Plants to Turn Brown?

Mint turning brown is an unusual but dangerous occurrence. Fungal assaults are the primary reason mint leaves become brown. The mint’s health may be badly harmed by a rust fungus, which causes the leaves to become brown. In the presence of excessive wetness and high humidity levels, the rust fungus attacks. Furthermore, when you overwater the plants and the leaves retain water drops, the fungus has an easier time invading the foliage.

Rust is not the cause if the plant appears to be healthy on the surface but goes brown on the inside. The interior section of the plant receives insufficient sunshine and is susceptible to excessive humidity, causing the mint plant to become brown.


It’s critical to provide your plant with enough sunshine and good drainage to avoid the Rust Fungal illness.

It will keep the moisture level consistent and prevent fungal development. You should also alter your watering technique.

Water just the tops of the leaves, and make sure there are no water drops on the leaves.

Trim back the core section of the plant if it starts to turn brown. Check for brown leaves and stems inside the plant on a regular basis and cut them off.

What Causes Mint Plants to Turn Black?

If any of the aforementioned problems are not addressed, the mint will dry out, decay, and become black. When exposed to high temperatures and bright sunshine for an extended period of time, mint paint can become black. The mint plant will become black as a result of overfertilization and a higher pH in the soil.


Avoid exposing the mint plant to direct sunlight for an extended period of time. Maintaining a temperature range of 25-35 degrees Celsius is crucial.

If your soil has an alkaline pH, you may balance it by adding acidifying nitrogen or sphagnum peat.

Use quick-release commercial fertilizers sparingly on the mint plant. When organic fertilizer is required, use it.

Frequently Asked Questions

What is the appearance of overwatered mint?

A mint plant that has been overwatered appears to be dangling with yellow leaves. Overwatering mint plants can also cause the Rust Fungus to infiltrate the plant and turn it brown.

How can you revive a mint plant that has been overwatered?

Check the drainage holes on your mint plant if it’s in a pot. Open daring holes if they’re closed. If these holes are insufficient, add more to increase drainage. If you’re using ground-planted mint, add well-rotted compost or dried leaves to the soil to absorb excess moisture and promote drainage.


Mint is a simple plant to cultivate, but our small errors may cause the plant to change color. I’m hoping that by following these instructions, you’ll be able to prevent your mint plant from becoming yellow, brown, black, or purple.

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