Begonias are colourful and attractive perennial plants that are easy to grow and care for. Because of this, these hardy plants have become a favourite with UK gardeners looking for low-maintenance plants to supply a splash of colour in hanging baskets or plant borders. Begonia care is usually straightforward, however, occasionally gardeners may discover that their begonia leaves have become covered in a white powdery substance. Below we look at the causes of this problem and easy, quick, and affordable ways to tackle the issue.

Begonia Powdery Mildew
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What Causes Begonia Leaves to Turn White?

White Powdery Mildew on Begonia leaves is caused by a plant fungal disease called Odium begoniae. This fungus spreads over the leaves of the plants and is identifiable by a film of thin white powder which can quickly spread across the plant. The white mildew can also spread to the stem and flowers of the plant if left untreated and leaves under the fungus may turn brown or yellow.

The fungus will not generally harm or kill off your plants, as most plant fungi rely upon the leaves of the plant to feed. However, it can begin to affect the level of growth of the plant so is not something you should ignore.

Can Begonia White Leaf Fungus Infect Other Plants?

The Odium Begoniae fungus is not transferable to other plants but will quickly spread and move to other Begonia plants around them. So, once you spot the white powdery mildew, you need to make sure to tackle the issue as quickly as possible.

How Does the Powdery Mildew on Begonia Plants Spread?

The fungi on Begonias growing on leaves can spread easily when spores are moved physically by wind and breezes blowing through the plants. Humidity and moisture levels do not affect how successful the plant is in developing.

How Do You Stop the Spread of White Powder on the Plant Leaves of Begonias?

Once you spot white powdery mildew on your Begonia plants, your first step should be to make sure that the fungus doesn’t spread to other parts of the plant or other Begonia plants.

If the plants are potted, make sure to move them so there is a good space between the infected plants and the healthy plants. You should also do some leaf cuttings of the infected area to remove the fungus entirely.

How to Treat White Leaves on Begonia Plants?

There are a couple of things that you can try and do to treat the problem although there are no guarantees that it will be successful but you won’t know until you try.

1. Water Down the Leaves

When you first spot the white powdery film, you can spray it down with water to remove the mould as best you can. While the leaves are still wet, prune the plant to cut leaves that are already irreparably infected.

2. Make Up a Home Plant Spray

You can also try spraying the leaves with your own homemade plant spray to treat the problem. Take 1 pint of water in a spray bottle and add one teaspoon of baking soda and give it a good shake to mix it all together. Then spray the leaves until they are covered with the solution.

After two or three days, you should check to see if there is a noticeable effect. If not, you may have to consider cutting off the leaves down to the stem to protect the rest of the plant.

3. Move the Infected Plants to the Green House

Unlike other plant fungal infections, Odium begoniae doesn’t thrive in hot and humid temperatures. So, placing the plants in a controlled hot environment like a greenhouse can help to kill off the spores and help you to save your plants.

Spotted Leaf of Begonia Plant
Odium Begoniae – Begonia Fungus

How to Avoid White Powdery Mildew on Your Begonias?

As they say, prevention is better than cure. If you are growing or planning on growing begonias, there are a couple of things you can do to try and safeguard your plants from infections that may arise.

1. Plant at Distances that Allows Good Ventilation

Ensure that you plant or place your pots at a good distance which will minimize the chances of fungus easily spreading between the plants.

2. Choose the Right Location

Begonia plants thrive in bright light and fast draining soil. Make sure that the plants are placed in the right parts of your garden to make sure that the chances of the fungus developing are minimal.

3. Disinfect Your Pruning Tools

If you have used your pruning tools to remove infected leaves from your plants, you need to make sure to disinfect them thoroughly before you use them again. Reusing unclean clippers on other non-infected Begonia plants may inadvertently help the fungus in spreading around your garden.

4. Monitor your Plants

The quicker you spot and deal with the fungus, the less chance the powder will have to spread to other leaves on the plant and other plants surrounding it. Make sure to check all your plants regularly so you can pick up on any discolouration, mould, and other issues.

Do you Need to Get Rid of Begonia Plants Which Have Developed White Leaves?

If you manage to notice the White Powdery Fungus on the leaves of your Begonia plants at an early stage, you may still be able to save the plant. Unless the infection is very developed there may still be scope to treat the problem. Your top priority should, however, be making sure that the infected leaves or plants are moved so they do not allow the fungus to spread further.


Begonia plants are a favourite with UK gardeners and the development of unsightly white powder on these bright colourful plants can be a frustrating issue. Luckily, if the problem has been caught early enough there should be no reason for you to have to remove the plant entirely. Instead, you can take steps to stop the fungus from spreading by spraying the infected leaves, if the fungus is more developed you can cut off the leaves. If your Begonias are potted, you can move the infected plants to ensure that the fungus doesn’t have the chance to move to your other non-infected Begonia plants. Follow the advice detailed above and there is every chance your Begonias will be perfectly healthy plants once more.

Garden Doctor Trev

Garden Doctor Tips

“Do not add infected plants to your compost pile, infected plants will need to be destroyed and disposed of!”

“Remove infected leaves immediately and destroy them, if you see the infection begin to spread, remove all infected plants!”

“When taking cuttings or any other job that involves using tools, ensure that you give them a thorough cleaning first!”

“If your infected begonias are potted, immediately move them to a greenhouse as the infection is less likely to thrive in a temperate and controlled environment!”

Frequently Asked Questions

How do you treat begonia powdery mildew?

The best solution to try and treat begonia mildew is to first give the leaves a wipe with a damp cloth and then when dry, spray the leaves with a water/ baking soda mix. If you find that this is unsuccessful, you will need to remove the infected part of the plant immediately to prevent it from spreading.

What does powdery mildew look like on begonias?

The appearance of powdery mildew on begonias will depend on the species of begonia. However, most forms of powdery mildew will appear as a white or grey powder on the leaves and stems of the plant.

Can you just wipe off powdery mildew?

Yes, you can wipe off powdery mildew with a damp cloth. However, this will only help to temporarily alleviate the problem. The best way to get rid of powdery mildew is by using a baking soda spray.

Baking soda is a natural fungicide that can be used to treat various types of fungal infections, including powdery mildew. To make the baking soda spray, mix 1 teaspoon of baking soda with 1 litre of water. Spray the mixture on the affected areas and let it sit for about 15 minutes. then rinse off with water.


Trevor Wright is not just a seasoned horticulturist; he’s the esteemed Garden Doctor. With a BSc in Horticulture and years of hands-on experience in the soil, Trevor has become a trusted mentor for all things gardening. As the founder of Garden Doctor, he’s committed to clarifying the intricacies of gardening, offering straightforward advice that’s rooted in years of practice. His writing is a garden of how-tos, savvy insights, and comprehensive guides that enable individuals to nurture and grow their garden dreams. When he’s not knee-deep in garden beds, Trevor is at his keyboard passing on his green-thumbed wisdom to budding gardeners, ensuring that the legacy of sustainable and joyful gardening blossoms far and wide.

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