April 12, 2026

Cures for Powdery Mildew

Vicky Okahas
April 12, 2026

QUICK TIP: The easiest way to prevent diseases in plants indoors or outdoors is to give them growing conditions as close as possible to the plant’s ideal conditions.

I have this information for a select number of crops that are suitable for containers and Tiny Spaces at Delectable Tiny Gardens and Manitu Okahas Programs

https://www.skool.com/delectable-tiny-gardens-4555/about

https://payhip.com/ManituOkahasPrograms

Powdery Mildew

Excerpt from a research project that I did for a member of Delectable Tiny Gardens

WHAT IS POWDERY MILDEW

Powdery mildew s a general term for a number of fungal diseases. I’m not going to get into the specifics of species here. It is in general defined by a white or grey film on the leaves and flowers of plants looks somewhat like someone dusted the plant with baby powder.

This fungal diseases can affect a wide range of plants both inside and outside. For most plants, a light infection does not pose a serious problem. For a few species, it can. The plants that powdery mildew causes the most problems for me are cucumbers, squash, and rosemary. When it does cause problems, it causes leaf drop, blossom drop, leaf curl, leaf twisting, an even the death of the death of the plant. When I loose rosemary in the winter, it is usually due to powdery mildew.

PREVENTION

The best practice is to prevent the disease before it occurs. It thrives is humid environments with little direct sunlight that are between 60*F and 80* F. Cool, humid nights encourage the growth of the fungus and dry warm days encourage the spread of the spore.

The best prevention in general is to lower the humidity a bit if you can, let the soil run just a tad bit on the dry side, and make sure the plants have good air flow. Never over fertilize the plants with nitrogen as that encourages disease prone growth.

The best preventive is sunlight. For my rosemary, I take it outside during the winter every time the weather is warm enough (above 45* F).

WHAT TO DO IF YOU SEE POWDERY MILDEW

Isolate the plant if you can and remove diseased foliage if you can.
Remove all plant debris that could carry the spore and destroy it . Do not compost it.
Treat the plants with a fungicide. Some of the safest ones to use are sulfur or copper based compounds or baking soda. Treat the plants as soon as you see signs, but remove affected foliage if possible.

My preference is to use a baking soda spray.

Home made sprays for powdery mildew.

mix 1 teaspoon baking soda into 1 quart water.

mix 1 teaspoon vinegar into 1 quart water.

The full article is found at Delectable Tiny Gardens.

Delectable Tiny Gardens

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www.skool.com/delectable-tiny-gardens-4555/about