It’s best to apply any fungicidal spray outside to prevent drift of the particles in your home. The good news: Although powdery mildew is an unattractive nuisance, it's rarely fatal to your plants. By: Bonnie L. Grant, Certified Urban Agriculturist. The fungi spores reside in plant buds, as well as overwintering in plant debris and are then carried to your plants via wind, insects, and splashing water. As the disease spreads, the entire plant material can be affected with the fluffy white fungus. Common plants affected by indoor powdery mildew are: If powdery mildew on houseplants is present on all specimens and cultural control is not effective, advance to chemical control. That's not always achievable, though, so you can also focus on a few other rules of thumb; First, when planting your garden, choose healthy plants and work to keep them that way. Happy holidays from all of us at Gardening Know How. Sign up to get all the latest gardening tips! This is where the fungus gathers the nutrients that it needs. This can help prevent the spread and growth of any fungi already present among your plants. True to its name, this fungus covers plant leaves and stems with what looks like powdered sugar. Using this powdery mildew control indoors is safe and non-toxic and effective on some, but not all, species of plants. Find more gardening information on Gardening Know How: Keep up to date with all that's happening in and around the garden. It’s not talcum powder and it’s not flour. Additionally, avoid fertilizing the affected plants until you think you have your powdery mildew outbreak under control—the spores favor young, succulent growth, so fertilizing while an infection is still present can actually increase the spread. As the name implies, powdery mildew presents as dusty splotches of white or gray power on the leaves and stems of infected plants. While almost no type of plant is immune--unless they're specifically bred resistant hybrids--certain species are more susceptible than others, including lilacs, flowering crab apple trees, phlox, red bee balm plants, roses, squash, cucumbers, and more. Lastly, try to avoid watering plants from above (with the exception of rain, of course), as dampening the leaves can encourage more mildew growth. Powdery mildew on houseplants is a fungal disease. Initially, it produces circular powdery white spots on the foliage of plants. You may also add 1 tablespoon (5 mL.) Wash your hands and clean your clippers with alcohol wipes after finishing to further prevent spread. Use organic milk that is free of hormones and preservatives. Read more articles about General Houseplant Care. The white substance rubs off easily with your fingers or a cloth. The leaves themselves may start to wilt and get mottled in appearance while the mildew spreads quickly throughout the plant. While removing and destroying all infected plants is the ideal solution, it's not very practical—understandably, few gardeners are willing to sacrifice their peonies or squash every time there is a powdery mildew outbreak. Elizabeth Bush, Virginia Polytechnic Institute and State University, Bugwood.org, Milk Fertilizer Benefits: Using Milk Fertilizer On Plants, Begonia Powdery Mildew Control – How To Treat Begonia Powdery Mildew, Onions With Powdery Mildew – Tips On Treating Onion Powdery Mildew, Grateful Gardening: How To Show Garden Gratitude, Indoor Winter Savory Care: How To Care For Winter Savory Inside, Fall Themed Fairy Gardens: How To Make A Mini-Thanksgiving Garden. As the disease spreads, the entire plant material can be affected with the fluffy white fungus. By using The Spruce, you accept our, How to Control Powdery Mildew With a Homemade Spray, How to Treat and Prevent Black Spots on Roses, How to Prevent Powdery Mildew on Plants Using Baking Soda, Downy Mildew - a Problem for Impatiens Plants, 10 Common Rose Problems (and How to Fix Them), Save Your Tomato Plants From These Common Diseases, How to Identify, Treat, and Prevent Anthracnose, How to Use Milk Spray to Control Powdery Mildew, What Are These Black Spots on My Phalaenopsis Orchid Leaves, How to Identify, Treat, and Prevent Aster Yellows, How to Identify, Treat, and Prevent Clubroot, Use Baking Soda Spray to Cure Plant Fungal Problems. Learn How To Store And Plant Bare Root Strawberries, Harvesting Plant Seeds: Seed Saving Activities For Children, Plant Trampling And Theft In Gardens: How To Protect Plants From Strangers, The Bountiful Garden: Bringing The Garden To Thanksgiving, Overwintering Containers And End Of Season Cleanup, Must Have Winter Shrubs – Top 7 Shrubs For Winter Interest, Enclosed Porch Garden – Indoor Gardening On The Porch. Mark Turner / The Image Bank / Getty Images. Now that you know your plants are susceptible to powdery mildew, you'll need to take a few steps to prevent its spread or reoccurrence. White Powdery Mildew is actually a fungal disease. Although powdery mildew can impact a variety of different kinds of plants, each fungal infection is "host-specific," meaning the breed of fungi infecting that plant is specific to that varietal. It is very contagious and once one part is affected, it will infect the rest of the plant if not checked. A home remedy made from baking soda is also an effective preventative, while one made from milk is thought to prevent powdery mildew before it starts.