Mold and Mildew on Your Herbs

Herb plants growing in six separate square containers

The Spruce / Almar Creative

It is often said that herbs thrive on neglect. While this isn't completely true, it can be easier to find success growing herbs than with many other garden plants. One benefit is that most herbs do not suffer many of the problems that plague flowers and vegetables. Something that you could run into though when growing herbs is a problem with mildew or mold. Both can damage and kill even the most prolific herbs.

How to Spot Mold and Mildew on Herbs

Most herbs thrive in fairly dry conditions. They need proper ventilation and sunlight to prevent the kind of environment that produces molds and mildews. One common mistake many beginning gardeners make is overplanting. As the plants grow larger, they crowd each other and receive less air circulation and sunlight, which is vital for evaporation. Too much moisture on the leaves and stems leads to mold and mildew.

  • Mold appears on plants as a slimy, brown, or black area. Mold can occur on leaves or stems..
  • Mildew is a powdery or fuzzy grayish patch. This most often occurs on the leaves but can become noticeable on the stem as well.

If you see either of these signs on your herbs, there are some emergency steps that you should take. The primary goal is to prevent more damage by eliminating conditions unfavorable to your plants.

Mold growing on herb leaves and hanging over edge of plant container

The Spruce / Almar Creative

Eliminating and Preventing Mold and Mildew

When you notice mold or mildew in your garden, it is best to act fast. An infected leaf can quickly become an infected plant and, if ignored, the problem can spread to other plants.

Prune off the affected area

This is as simple as pinching off the leaves where you see mold or mildew or cutting entire stems that show damage. Be sure to wash your hands and your garden shears before moving to a healthy plant and don't drop the moldy leaves onto the soil. Dispose of diseased plant matter away from your garden and compost pile.

Herb plant with mildew on leaves being pruned with small scissors

The Spruce / Almar Creative

Thin the foliage and possibly the plants ​

This will improve air circulation, so cut down the bushiest parts of the herbs to give them more room. If necessary, move an entire plant, so its neighbors have more space to breathe. Many herbs do best if cut back regularly. Use the fresh herbs in recipes or dry them and store in a cool dark cupboard for future use.

Water less often

You may be overwatering and inadvertently allowing the moisture-loving molds to proliferate. Don't water on a schedule. Instead, learn to recognize the signs that your garden needs water.

Water only the roots

Unless the summer winds are kicking up a lot of dust, do not water any part of your plants that are above ground. Water the base only and give the roots a healthy dose of water.

Herb plant being watered over only the roots with watering can

The Spruce / Almar Creative

Remove the entire plant

Sometimes, removal of the plant is necessary. If you find that all of the remedies mentioned do not improve your herb's health, you may have to remove it and dispose of or relocate the plant. Place it in a pot and consider the plant in quarantine until it is healthy again. Or, dispose of the plant properly and begin with new stock.

Herb plant removed entirely from plant container

The Spruce / Almar Creative

Chemical Sprays and Treatments

While it can be tempting to run to the nursery for a chemical solution at the first signs of mold, resist the urge. Whether you plan to use your herbs fresh or dried, the chemical compounds from chemical sprays and treatments can linger on the plant.

Herbs are mostly hardy and fairly resilient, so a chemical-free approach is usually pretty effective in combatting mold and mildew. It does require a little more work, and you do need to pay attention to your plants, but that's part of having a successful garden.

Article Sources
The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Shepherd, Lizz. The Complete Guide to Growing Vegetables, Flowers, Fruits, and Herbs from Containers: Everything You Need to Know Explained Simply. Atlantic Publication

  2. Millard, Elizabeth. Indoor Kitchen Gardening: Turn Your Home into a Year-Round Vegetable Garden. Cool Springs Press, 2014