A Midsummer Dahlia Q&A

It’s that time of year when we begin to stress a little over our dahlias. But there’s really no need— midsummer dahlias issues are normal when you grow in a hot humid climate that is less than desirable for dahlias. We all experience issues at one time or another during the season. I’m sharing some questions that I have received recently and answering them for you here b/c I promise you— You aren’t the only one!!

Question: I have grown dahlias for years. This year, several have been hit by powdery mildew. I have sprayed and sprayed a commercial organic neem oil and removed impacted leaves - it just keeps moving through the plants.
Answer: Neem is often proclaimed as the answer to a lot of things while gardening and it can be very helpful. But it’s not the only tool in the box. Neem is a great first go to but it can only combat so much. For powdery mildew issues, Copper fungicide is a great next step when neem won’t cut it. Also Cease and Milstop are great options too.

Question: Ugh! What’s wrong!? My dahlia blooms are deformed or not opening much before they die. Plus their color is not as brilliant as last year. Help…
Answer: Two parter here— Deformity in blooms is usually a thrip issue. When one side of the flower opens but not the other- usually means you have some thrip problems. Spraying with Capt’n Jacks Dead Bug Brew (Spinosad - active ingredient) is helpful. Alternate with a spray like Bio-Ceres WP. Don’t spray the same thing week after week, always alternate your sprays.
As to the color issue: High heat and longer daylight hours cause dahlias to change color. Don’t worry, they’ll fix themselves this fall. Just enjoy the rainbow color changing show!

Question: My 12 dahlias are in 7 gallon grow bags planted on May 5. They are no where near budding. Am I over fertilizing, too hot? When should I expect flowers?
Answer: Dahlias usually begin blooming in late summer. The earliest varieties take at least 65-70 days and some take up to 120. The heat will slow them down. From a May planting, usually you’ll see dahlias in early August. But Fall is their primetime, so hang in there— the show hasn’t begun yet!

Question: Have you seen spider mites yet?
Answer: I wish I could say no, but they have been pretty bad this year actually. The high heat and dryness we have had during several parts of the season so far have brought on lots of spider mites. I tried Conserve (the commercial version of Capt’n Jacks) and it did help but I had to pull out the big guns eventually and go with Avid. Our recent cut back (early July) is helping b/c we are removing a lot of the infested material. So we’ll be on a pretty strict spray regimen for at least the next 2 months until it cools and we get some more moisture.

Mid summer is hard but keep on keeping on— just make sure you are feeding, taking care of bugs and watering. You’re hard work will pay off!!

And if you are really stressed— Read my blog post from last summer: Your Dahlias Need a Therapist