I planted morning glories next to a thriving clematis last year and this year the clematis all but died. Are morning glories poisonous to clematis?
Morning glories are not poisonous to clematis but their vigorous growth may have made your clematis more vulnerable to one of the several diseases that affect clematis when air circulation around their stems is restricted. Without knowing the symptoms, it is possible that your clematis may have succumbed to Clematis Wilt, a common fungal disease affecting clematis, also known as Clematis Leaf and Stem Spot.
Your best approach is to prune out any damaged parts of your clematis: this will help to prevent the spread of a fungal disease. Even if the stems seem to have been decimated by the disease, the plant’s roots can generally survive, and you will likely find that your clematis will re-emerge in the spring.
Clematis is also susceptible to Root Rot, and if you see signs of rotted plant tissue near the soil line, this may be what is affecting your clematis. Once again, remove infected leaves when you see them, and make sure there is good air circulation around the base of the plant.
A thorough clean-up around your clematis in the fall is an essential in treating and preventing Clematis Wilt and other fungal diseases. Your vines should be pruned as close to the ground as possible, and all dead stems and leaves should be removed and destroyed. Making sure that your soil is well-drained will also be helpful in preventing fungal and other diseases.
Here is a link to a helpful fact sheet on the diseases that affect clematis: