Question
QUESTION: Dear C.L. Fornari,
I raised from seed a gorgeous array of giant California Zinnias and they have developed a white film on their leaves, even the newer ones.
I am a new gardener and reside in Southern California and am alarmed at this turn of events.
Thank you for your time!
Jackie

ANSWER: Jackie,
Unfortunately, many Zinnias are prone to Mildew, which is what you are seeing. The good news is that although it weakens the plant it seldom kills it, and when zinnias are picked for bouquets you usually strip off the leaves anyway. If you want to control the mildew (you won't get rid of it but you can slow it down) spray with a product called "Green Cure" - this is a super baking soda.  If you can't find Green Cure make your own spray (not as good but better than doing nothing) from one tablespoon of horticultural oil - available at garden centers - and two tablespoons of baking soda per gallon of water.  Mix well in a pressure sprayer and apply once a week.

In the future, if you begin spraying when the zinnias are small you can keep the mildew at bay for quite awhile, but the key is to spray BEFORE the plant has the problem.

Also, water the plants in the morning only, and water deeply less often...keeping the leaves wet or damp contributes to this problem.  Zinnias are native to Mexico, so they like hot, dry weather!  

When you pull the plants out when they are finished flowering don't put the stems and foliage in a compost pile - put it in a brush pile or the garbage according to your local regulations.  You don't what to spread the mildew spores anymore than you have to.

I hope this helps!
C.L. Fornari

---------- FOLLOW-UP ----------

QUESTION: Thank you very much!
I'm sure my poor zinnias are done for and will have to remove them. I was curious if some echinaceas (hardy coneflowers) were likely catch the fungus as well?
Thank you for your knowledge!
Jackie

Answer
Jackie,
Although I have never known echinacea to get powdery mildew, I can't say that it is impossible!  Sometimes plants have problems that are unexpected - but by the same token, sometimes plants succeed against all odds.  If you want to protect your echinacea, spray them either with Green Cure, Serenade, or the baking soda mix I outlined before. Any of these will help protect them.  Or you could do what I do, and leave them as they are an hope for the best.  Remember: I always say that you aren't a gardener until you have plants that have died.  Congratulations - you are a gardener!  Whether your plants do well or not, enjoy it all.  Gardening is a lot like life that way - no guarantees, and filled with both joys and sorrows - and as Anne Lamott says, as human beings we are entitled to the entire experience.
Amen and all the best,
C.L.