My phlox has white leaves. What can I do to stop it?

Garden Experts
My white phlox has leaves completely coated with a white substance; not only on the upper side, but also on the underside. I have already transplanted it because I thought it was not happy in its location, but it hasn’t recovered. The flowers then go brown, but what is most strange is that a pink phlox growing next to it has remained a beautiful specimen. What can I do? I hope you can help me, as I don’t want to dig it up – it was once a lovely plant!

The GARDENA gardening expert

Dear Ms. M., mildew has attacked your phlox plant. The summer phlox (Phlox paniculata) is comparatively susceptible to this disease, in particular the older varieties. Have a look under Phlox paniculata for some varieties which would suit you. Also, have a look at the large-leaf phloxes (Phlox amplifolia), which are less susceptible to mildew. The old garden saying applies here: “A summer garden without phlox is not a summer garden at all”! 

In addition to planting “better” varieties, it is important that you optimise the location conditions for your phlox plants, for example by achieving sufficient location ventilation. The phlox plants must not stand too close to each other, and the neighbouring plants may not grow too densely or high.