KC Gardens

Garden phlox with dead leaves


I planted a new tall garden phlox this year called shockwave. It is varigated foliage. It bloomed well but the leaves are looking as if they are dead on the lower two thirds of the 6 plants. Is this common or just an anomaly of this variety? I believe I have kept them well watered since they are new plants. Any suggestions would be helpful. - Carolyn -


  1. 8 months, 3 weeks ago

    The Shockwave, like all tall garden phlox, needs good air circulation (no crowding), no overhead water, and good drainage, no soggy soil.

    Without a photo of your plants, and a description of what the final 1/3 of the leaves look like here are some possibilities, given that the plants are in a good site.

    The most common disease problem with phlox is powdery mildew. Although Shockwave has some resistance, it could still succumb, exhibiting white powdery splotches on the leaf surface. Once this is one the plant, it is difficult to control. Good cultural practices (see above) will help, also do not overfertilize. Horticultural oil is a good control.

    Another possibility due to the hot, dry conditions we had, would be spider mites. In this case, the leaf would have more mottled white spots on top side of the leaves, with some webbing on the underside. The best thing to do is blast the plants with water, especially the underside of the leaves. This will knock the mites off.

    In either case, the symptoms would appear well-before the leaves have died. Examine the remaining leaves on your plants, or take a sample to your Extension Service. You might Google images of both powdery mildew on phlox and spider mites so you will know what to look for.

    Clean up the dead leaves, and do not compost them.

    Hope this helps.

    Carole Johnson County Extension Master Gardener

Sign in with Facebook to comment.

Copyright 2014 The Kansas City Star.  All  rights  reserved.  This material may not be published, broadcast, rewritten  or redistributed.