Get Almanac's Daily Updates Extended Forecasts Where to Buy Contact Us

How to Prevent and Treat Gray Mold (Botrytis) in Your Garden

Gray mold has compromised these Riesling grapes.

Photo Credit
Photo by Rob & Lisa Meehan, Wikimedia Commons

Simple tips to protect your plants from one of the most common garden fungi.

Written By: Catherine Boeckmann Executive Digital Editor and Master Gardener

Do you ever look at your beautiful plants and see something fuzzy and gray? It might be Gray Mold (Botrytis), a common but nasty fungus that can strike your garden when you least expect it. It affects many parts of the plant: leaves, flowers, stems, and fruit. Luckily, with a few simple steps, you can identify, prevent, and treat this fungus before it spreads.

What Is Gray Mold?

Gray mold is a pesky fungal disease caused by the fungus Botrytis cinerea. It’s not picky about its host—this pathogen can go after many different garden plants, from flowers to vegetables. Once it shows up, it spreads fast, riding along on the wind, splashing water, garden tools, or even on your hands.

A quick note so the terms don’t get confusing:

  • The fungus itself is Botrytis cinerea.
  • The disease we see on plants is called gray mold.

Commonly Affected Plant Parts:

  • Leaves: Small brown or water-soaked spots that may develop fuzzy gray mold
  • Flowers: Wilting, browning, or fuzzy coating on petals
  • Stems: Gray mold can rot stems at the base or nodes
  • Fruits: Soft spots, rotting, and gray spore growth on tomatoes, strawberries, grapes, and other fruits
Gray Mold (Botrytis) on strawberry fruits.
Gray Mold caused by Botrytis fungus on strawberry fruits. Credit: Floki

Why It Happens:

This  develops when plants and their environment create the perfect storm for infection. This pathogen thrives in cool, damp, and stagnant conditions, especially when plants are stressed or damaged.

  • High humidity keeps leaves and stems moist, which allows fungal spores to germinate and spread.
  • Poor airflow prevents that moisture from evaporating, leaving a lingering damp layer on foliage and flowers.
  • Excessive watering—or water that splashes onto leaves—further increases surface moisture and can even spread spores from one plant part to another.
  • Decaying plant material (fallen leaves, old blossoms, pruned stems) acts as both food and a breeding ground, where the fungus produces more spores ready to infect healthy tissue.

Together, these factors weaken plants and make them vulnerable to infection. Even healthy plants can fall victim if conditions stay wet and stagnant long enough, since Botrytis is an opportunistic fungus that attacks wherever there’s soft, damaged, or aging tissue.

Read Next

Identification

How Gray Mold Spreads

Early recognition is key to stopping Gray Mold early.  Here’s how it progresses:

  1. Generally, small spots that appear water-soaked will form on the leaves. These might appear white at first.
  2. These spots will then change color from gray to brown, eventually covering most of the leaf. The brown coloration is what often causes people to confuse gray mold with brown mold.
  3. Under really humid conditions, grayish webbing may appear on the leaves. This webbing contains structures that contain fuzzy spores. Spores become active and are released with no activity at all.
  4. Petals, stems, and buds can also become infected.
  5. Eventually, all of the infected parts of the plant will be covered by a fuzzy gray growth .

Symptoms to Watch For

  • Gray, fuzzy mold on leaves, stems, flowers, or fruit
  • Wilting, browning, or softening of plant tissue
  • Rapid spread under cool, humid conditions
  • Small spots that enlarge quickly if untreated

Tip: Check plants regularly, especially during damp weather or in areas with dense foliage.

identify-gray-mold-botrytis.jpg
The fuzzy gray spores characteristic of botrytis infect an impatiens plant.
Photo Credit: Francesca Peduto Hand, The Ohio State University. 

Gardening Products

Control and Prevention

4. Control and Treatment

If Gray Mold appears, quick action is essential:

  • Prune Affected Areas: Cut away infected leaves, stems, or flowers using clean tools; dispose of infected material (don’t compost).
  • Use Fungicidal Treatments: Organic options like copper sprays or neem oil can help—follow instructions carefully.
  • Improve Airflow and Reduce Humidity: Thin crowded plants and remove excess foliage; avoid overhead watering.
  • Rotate Crops: Avoid planting susceptible plants in the same location year after year.
  • Monitor Regularly: Inspect plants daily in damp conditions and treat early.

Extra Tips:

  • Handle plants when dry to prevent spore spread.
  • Keep mulch away from stems to avoid moisture buildup.
  • Clean garden tools regularly to prevent spreading spores.
  • Companion planting with basil or marigolds may reduce fungal pressure.

Prevention

Stopping Gray Mold before it starts is the most effective approach:

  1. Space Plants Properly: Ensure good air circulation by avoiding overcrowding.
  2. Water Strategically: Water at the base, not overhead, and do so in the morning to allow leaves to dry.
  3. Remove Debris: Clear fallen leaves, rotting flowers, and decaying fruit promptly.
  4. Choose Resistant Varieties: Plant types labeled “disease-resistant” reduce risk.
  5. Maintain Plant Health: Healthy plants resist infection better—fertilize appropriately and avoid overwatering.

Frequently Asked Questions (FAQ) About Gray Mold (Botrytis)

Q: Can Gray Mold kill my plants?

A: It can damage and weaken plants, especially young or stressed ones, but with prompt prevention and treatment, serious damage is usually avoidable.

Q: How can I prevent Gray Mold in my garden?

A: Ensure good air circulation, water at the base of plants, remove debris promptly, choose resistant varieties, and maintain overall plant health.

Q: What treatments work against Gray Mold?

A: Organic fungicides like copper sprays or neem oil are effective. Prune infected plant parts, improve airflow, reduce humidity, and monitor plants regularly.

Q: Can I eat fruits affected by Gray Mold?

A: No, any fruits showing signs of Gray Mold should be discarded, as the fungus can penetrate deeply and spoil the tissue.

Q: Does Gray Mold only affect certain plants?

A: Gray Mold can infect a wide range of plants, but it’s most common on tomatoes, strawberries, grapes, and roses in home gardens. 


While Gray Mold can be a persistent challenge, early prevention and prompt treatment keep your garden healthy. By monitoring your plants, maintaining airflow, and using simple control measures, you can protect your garden from this common fungus and enjoy thriving plants all season long.

Garden Pests
About The Author
Catherine Boeckmann

Catherine Boeckmann

Executive Digital Editor and Master Gardener

Catherine Boeckmann is the Executive Digital Editor of Almanac.com, the website companion of The Old Farmer's Almanac. She covers gardening, plants, pest control, soil composition, seasonal and moon c...
Read More from Catherine Boeckmann

More Like This

Comments

<span>Jennifer</span> Sat, 11/06/2021 - 16:28
what spray do I have to get to kill gray mold in my plant soil? I've tried all natural ways to get rid of it but nothing working. I believe I need a chemical spray now and I have it in some herd plants too. Its still growing in soil this is dry, I even bleached my whole house and still got it back. please help me.
<span>S. Eberhardt</span> Tue, 05/31/2022 - 16:55
Also want to know how to rid gray mold from soil.
<span>Jon</span> Mon, 11/29/2021 - 17:15
I think you need to get new soil and put it somewhere else.
<span>Jim</span> Wed, 10/10/2018 - 18:22
all plants in my greenhouse are finished but whats left is heavily infested with botritis. when i remove the plants, spores are going to fill the air. the soil will be covered with spores. my question is; can i use that soil again? can i take the soil outside and add alot of nitrogen to start it composting?
<a title="View user profile." href="/author/editors">The Editors</a> Fri, 10/12/2018 - 14:54

Botrytis spores can be cooked away in a compost pile, but only if the pile reaches upwards of 131°F (55°C) and stays at that temperature for several days. That being said, we wouldn't recommend using the soil in your greenhouse again, just in case the composting didn't do the job completely. 

 <span>Jim</span> Fri, 10/12/2018 - 16:22
thanks for the recommendation. what do you think i can add to the 5 yards of soil to get it hot enough to kill the botritis spores. i'm thinking, cottonseed meal & straw. i want to be organic & economical.
<span>Connie</span> Sat, 02/12/2022 - 12:24
We had a beautiful willow tree die of this. An elderly neighbor told us to put a black tarp over the entire area after we removed the dying tree for as many days as we could with the sun beating on it. We left it on for several weeks just to make sure. It worked! We planted a new willow about 6 months later and it’s been about 4 years and it’s doing great. I think the heat all day killed it.
<span>Ann</span> Wed, 08/17/2016 - 10:03
is there a natural remedy to correct this problem without using chemical sprays?
<a title="View user profile." href="/author/editors">The Editors</a> Wed, 08/17/2016 - 11:49

Unfortunately, it can be difficult to get rid of gray mold without chemical sprays. We would recommend following our tips like destroying all plants that are infected and making sure that your plants are not in an overly moist environment. The article provides some natural and easy prevention methods that might be able to keep you from having to use a chemical spray.

 <span>Kathee</span> Sun, 08/07/2016 - 20:42
I just planted some hydrangea. Two days later when I went to water them they have large shiny white patches on most of the leaves. What is the problem?