Thus, it is much more upsetting and distressing to observe black spots developing on its fragrant leaf.
The most frequent causes of black spots on mint leaves include pest infestations and diseases such leaf spot diseases, verticillium wilt, mint rust, and leaf blight. When the top 1-2 inches of the potting soil feel dry, water your mint to solve the issue. Ensure that the plant is also in a well-ventilated space. Use insecticidal soap or neem oil to control pest infestations.
I’ll describe the typical causes of these black spots on Mint leaves in this article, along with remedies.
What Do Black Spots on Mint Leaves Indicate?
Are you curious to know what it means when your mint leaves starts having black spots?
Mint plants that have black spots is a sign that your plant is in trouble. Your mint plant might become distressed for a variety of causes and in several ways. Do not fear; we will address each reason and its solution in the near future.
Just keep in mind that while mint plants are simple to establish, maintaining their health demands proper care and upkeep.
Therefore, it is imperative that you act quickly to stop it from spreading to the rest of the plant as soon as you observe any color change in your mint leaves, such as mint plant leaves turning black or black spots on mint leaves.
What Causes Black Spots on Mint Leaves?
1. Overwatering & Poor Drainage
You may have heard that mint plants need to be watered frequently, but be aware that overwatering can cause the plant to develop overgrown roots and black or brown leaves on the bottom of the plant. Overwatering in this context refers to watering the mint plant every one to two days even though it is not summer.
Inadequate drainage systems might further harm the plant because mint plants have extremely delicate roots. You must be suspicious and look for an expanded root when you find the leaves lovely and full because they are already a tough and quickly growing herb.
Keep in mind that mint grows best in a light soil with good drainage so that water can easily run through it and the roots can remain strong to support its growth.
2. Mint Leaf Blight
Another fungus that affects plants and results in black dots on leaves is mint leaf blight. A major outbreak of mint rust is the most frequent reason for leaf blight.
It is brought on by the fungus Cephalosporium spp. and typically spread by water splashes.
The leaf blight fungus flourishes in damp winters. However, if the weather is cool and damp in the spring, it can attack.
Although it can spread to the stems, it mostly affects the mint leaves.
On the lower foliage, the symptoms first appear as erratic black patches. The leaves are then covered in black patches as a result. Quickly dying and dropping off are the diseased leaves.
The impacted stems could potentially pass away and start to decay. Cuttings and newly transplanted plants are frequently used to spread mint leaf disease.
3. Verticillium Wilt
A fungus called verticillium wilt mainly harms peppermint. But it can harm any type of mint, resulting in widespread leaf spotting and dieback.
The soil-borne fungus Verticillium dahlia is responsible for this fungi disease.
The growth media becomes contaminated by verticillium wilt. Before germinating and growing in hot, humid spring or summer temperatures, the spores lie dormant for years.
The higher parts of the mint plant are initially affected, then the roots. As a result, leaves that are nearer the earth are frequently where black spotting is first detected.
Another fungus that affects mint leaves and puts black patches on them is anthracnose. In warm, humid weather, it spreads swiftly.
The fungus issue can be made worse by poor aeration, excessive watering, and a lack of light.
On lower and older foliage, anthracnose first manifests as tiny, submerged water-soaked areas. Lesions can be brown or yellowish orange in color.
Additionally susceptible to the illness are immature leaves, stems, and shoots.
The brown spots frequently enlarge, darken, and coalesce as the illness spreads. Your mint eventually loses all of its leaves and turns completely black.
5. Mint Rust
The most frequent cause of black dots on the leaves of numerous mint species is mint rust. In late spring or the beginning of summer, the fungal illness becomes apparent. The fungus Puccinia menthae, which causes mint rust, thrives when the conditions are right.
Tiny dusty specks are the disease’s initial symptom. They have a vivid orange to yellow hue. The backs of mint leaves have these dots, which give them a dusty appearance. Your mint will become weak and unsightly if the issue is not resolved. Your mint plant is consequently more susceptible to leaf blight and fungal leaf spots. By October, the leaf patches will have gone black.
How Can I Determine If My Mint Is Over-fertilized?
Are you scared that you might be over-fertilizing your mint? Then you need to perform a test to know this.
Using a pH meter is one quick and simple technique to check for over-fertilization.
Your mint plant needs to be corrected if the tester’s result is less than 7, which indicates that it contains too much salt. Any garden or plant center may simply provide a pH meter.
Checking for salt deposits or any white material on top of the soil is another option. High salt levels indicate overfertilization.
How Often Should I Water My Mint?
Are you curious to know how often you need to water your mint so you could set up a watering schedule?
You need to water your mint when the top inch of soil is dry. Mint typically requires watering twice a week if grown indoors in pots. Water plants in outdoor containers two to three times per week.
Water thoroughly once every two weeks if growing mint in the ground outside. Each morning, water the mint seedlings in their trays.
How Can I Grow Mint Plants in Water?
If you desire, you can actually grow mint in water. Despite the fact that mint cannot permanently survive in water, propagating it is a fantastic technique to keep it alive in your kitchen for a little time or to increase your mint production.
Cut pieces of your fully grown mint plant that are five to seven inches long, and put them in a vase or water bottle. The mint will continue to grow normally if you place it somewhere that receives four to six hours of direct sunlight each day.
Mint may last for several weeks while it is growing in water. Once its roots have grown well, you may either plant it directly into the ground in your yard or transfer it into a pot to maintain indoors or outdoors.
How Much Water Does Mint Seedlings Need?
Are you planting mints for the first time? Are you curious to know how much water your seedlings will be needing?
You should give mint regular watering if you are starting it indoors before transplanting it to a container or a herb garden outside. After planting your trays, give them a nice shower first thing every morning.
You can cut down on watering to once every other day until your mint seedlings are between an inch and two inches tall.
Place your trays in a warm area, such as a tiny greenhouse, or in bright, indirect light indoors.
What is the Best Growing Condition for Mint Leaves?
The greatest strategy to prevent any disease or infection is to keep your plant healthy at all times.
Make sure the potting soil is always moist if you are growing mint in a pot.
I advise either using a hose or watering the mint plant from the soil or base.
For this plant, soil that is rich in organic matter, retains moisture, and drains excess water well is ideal.
Compared to areas with direct sunshine, this plant does better in areas with partial shade.
When new growth first sprouts in the spring, feed your plant with a balanced fertilizer or a herb.
To prevent a high salt level, frequently leach the soil.
How to Prevent Black Spots on Mint
- Use drip irrigation or self-watering pots instead of overhead irrigation.
- Avoid handling damp leaves or spraying water on them.
- Maintain proper hygiene by cleaning pruning tools with an alcohol or bleach solution after each use.
- Grass around your mint plants must be pulled.
- Encourage good airflow around your mint plants.
- Do not overwater.
Can I Consume Mint Leaves With Black Spots?
Does your mint leaves have black spots? Do you want to know if it’s safe for you to eat them?
You cannot and should not eat mint leaves if a fungus is the cause of the black or brown stains on them!
They can be consumed after being appropriately treated. But, that’s only if the black spots were caused by heat or irrigation problems.
Best Fungicide For Mint Plants
1. Ortho MAX Garden Disease Control Concentrate
With Ortho MAX Garden Disease Control Concentrate, you can guard your garden against diseases including rust, leaf spots, blights, mildew, and fruit rots. Diseases including leaf spots, rust, blights, fruit rots, mildews, scab, molds, and other plant ailments are stopped and prevented.
Use the concentrate on the aforementioned decorative vegetables, flowers, fruit trees, and vegetables after diluting it in accordance with the label’s instructions.
- Effective in stopping fungal outbreak
- Easy to use
- Some bottles leak during delivery.
Are there black spots on mint leaves? Mint (Mentha spp.) is a hardy perennial that thrives in U.S. Department of Agriculture plant hardiness zones 4 through 9 (depending on the species).
However, even this resilient plant can encounter difficulties. Your mint plants most likely have advanced stages of mint rust or leaf blight when they start to develop black spots on their leaves. In order to stop the disease from spreading once mint gets black spots, urgent action is required.