Powdery mildew is mostly caused by exposure to water. When plants, primarily in the broadleaf category like squash and to a lesser extent plants in the pea family, get too much water, a greyish/white powder will form on the leaves. If not addressed early in the formation stages, this condition can lead to serious crop damage and lower yields.

You’re in luck though. Powdery mildew is preventable and, better yet, treatable. Certain types of plants will actually invite or increase the chances of your vegetables getting powdery mildew. Such include members of the phlox or bee balm families. If you have these plants near your garden, it’s best to move them to another location or remove them altogether.

Ask yourself this question. Does your garden have adequate drainage? Otherwise, this could lead to improper movement of water under the soil and that could lead to powdery mildew and other diseases like root rot. The best way to create better drainage is to constantly add compost to your soil. Compost has been shown in many studies to increase soil volume and drainage, as well as providing the many nutrients your plants need to grow.

You may be following the two tips I just mentioned, but even the best laid plans can’t make up for what Mother Nature has to offer. If you lived in the northeastern United States in 2009, you experienced firsthand what can happen to your yard when it gets too much rain. If this occurs, you will most likely be exposed to powdery mildew. It is treatable, and your best remedy is a safe, natural spray such as neem oil or a mixture of one and a half tablespoons of baking soda, one teaspoon of vegetable oil, and one and a half gallons of warm water. Spray either of these on the affected areas and you should be good to go.

If you are experiencing a wetter than normal growing season, I recommend using a chamomile spray or compost tea mix and spray directly onto plants to help prevent and/or delay future outbreaks of powdery mildew. Both of these methods are great ways to make your life easier in your home garden.

Combine these preventative and treatment methods above and you’ll be well on your way to a powdery mildew-free home garden.