Question
I live in Minnesota where winters are brutal and store my two
Habiscus (one plant, one small tree) in a sunroom......the sunroom is heated but nightime temps in the sunroom can get down to the low 50"s.  They seem to do okay and develop a blossom or two every now and then.
My question is what causes a powdery almost granular powder to form on the leaves every now and again, especially on the Habiscus plant, my wife would like to toss them because they tend
to make a mess when they go thru this process but I enjoy the Habiscus too much and would like to believe they give off oxygen

Am I crazy
Tom

Answer
Tom,

You are not crazy. Not only does your hibiscus give off oxygen but in the process it also cleans pollutants from the air in your home. Not to speak about how beautiful and soul renewing those blossoms are in the middle of winter.

I believe that your problem is powdery mildew. It would look like a cross between snow and mold and can be wiped off of the leaves. To get rid of it I would spray the entire plant with a Lysol spray (can be generic version) every 3-4 days for 5 treatments. Then sit tight and see if it comes back. I believe that the coolness is part of your problem and since spring is just around the corner that problem should be resolved for this year. They do love the sun so your sunroom is great and this helps it bloom all winter.

If you haven't already cut the plant back it is time to do that. Cut all the branches back by half but not past the lowest leaf on the branch. You can cut all branches back to 1 or 2 leaves. That will cause the plants to get bushier and produce even more blooms. Pruning will give you less plant to spray with the Lysol.  Also pick up some blooming plant fertilizer if you are not already using it. That will help it bloom faster and stronger. Follow the instructions on the fertilizer. If you have more questions feel free to write again. Good luck!

Darlene