Why is my rhododendron so sickly

Asked May 9, 2019, 3:01 PM EDT

I have a large,generic rhododendron next to my house,and the plant is several decades old. It has always been healthy and blooming,and I pruned it occasionally tincontrol its height. Last season I noticed dieback,woodier looking branches, and overall a less healthy plant. I pruned back some branches but that doesn’t seem to have helped. I used composted leaves as fertilizer. I haven’t put any fungicide or chemicals on it. Could this be simply old age,would heavy pruning help or should I give up and start with a new plant. I filled this form out once already,but not sure it was sent, so this may be a duplicate.

New Castle County Delaware

1 Response


Rhododendrons have suffered from fluctuating weather conditions of temperature and rainfall in our area for the past year. Plants actually do better if winter temperatures get cold and stay cold. Rhododendrons are also susceptible to some fungi that cause plant disease and dieback. Many of these fungi are opportunistic and invade plants that are stressed or wounded.

I recommend pruning your rhododendron back pretty heavily after it blooms this spring. Prune it to a low shape, with several large branches. That will remove the dead branches and open up the shrub for good air circulation. Mulch underneath may help. I don't think you need to apply and pesticides at this time.

Thank you for contacting Cooperative Extension,