I have an oxalis that has a very special meaning to me. It is about 25 years old. It started getting white spots on it after I repotted it a few years ago. I have been using neem oil on it but have not been religious about it and the spots return. I live in No. Idaho, so no sun here for most of the winter. Can I move to dark closet and water minimally for the winter and hope for the best when the sun returns? Or should I be vigilant with the neem oil and hope for the best? It is in a window that gets light for several hours a day....
Certified GKH Gardening Expert
They do like a dormancy every now and then. I will include a link at the end for more information.
Now, as for the powdery mildew... There are many effective ways to control this. Neem oil is not always the most effective, but it works most of the time. I recommend using other oils as well. Garlic oil, rosemary oil, and cinnamon oil are very good methods for controlling these infection. Mix a half teaspoon into a spray bottle of water, and spray as often as you need.
This article is on the care of Oxalis: https://www.gardeningknowhow.com/houseplants/shamrock/growing-shamrock-plants.htm
This collection of articles will give you more information on using these oils, and more: https://www.gardeningknowhow.com/special/organic/