Powdery mildew on houseplants
Common causes of powdery mildew and the first things to check, summarized from 13 PlantGrail care records across 11 plants (as of ).
What causes powdery mildew on houseplants?
It depends on the plant and how it is kept, so check the plant pages below. For Begonia, the records explain it like this: Powdery mildew (Oidium begoniae, Erysiphales fungi) germinates when begonia foliage experiences 4+ hours of surface moisture combined with stagnant air, not merely high humidity. Begonias' waxy, cupped leaves trap humidity pockets that create microenvironments ideal for spore proliferation. Unlike root rot pathogens, powdery mildew spreads via airborne spores that colonize leaf surfaces epiphytically without penetrating tissue initially.
Common first steps
- Immediate isolation: Move affected plant 3+ feet from others to prevent airborne spore spread
- Surgical removal: Cut ALL leaves showing white powdery patches with sterile scissors; dispose in sealed bag (do not compost)
- Alternating fungicide protocol: Week 1 - copper fungicide spray covering all leaf surfaces; Week 2 - neem oil + baking soda mix (1 gal water, 2 tbsp baking soda, 1 tbsp Castile soap, 2 tbsp neem oil)
Plants with records for powdery mildew
Most records first. Open a plant for its own causes and fixes.
- begonia Begonia spp.Plant care guide
- rubber plant Ficus elasticaPlant care guide
- jade plant Crassula ovataPlant care guide
- begonia angel wing
- african violet Read the guide
- rose Rosa spp.Plant care guide
- lagerstroemia indica Lagerstroemia Indica
- begonia beefsteak begonia beefsteak
- begonia masoniana begonia masoniana
- pilea involucrata pilea involucrata
- strawberry Plant care guide
Questions about powdery mildew
Which plants have the most records for powdery mildew?
begonia, rubber plant, jade plant, begonia angel wing, african violet and 6 others.
Can powdery mildew be prevented?
Maintain 50-60% humidity maximum for cane begonias (rex varieties tolerate 60-70%); ensure constant gentle airflow via fan 4+ hours daily; space plants 12-18 inches apart; water at soil level exclusively avoiding leaf wetting; quarantine new acquisitions 14 days minimum before introducing to collection
What are these records?
This page summarizes 13 PlantGrail care records on powdery mildew. Records describe care topics; they are not counts of observed plants or treatment outcomes.