I have 2 plants, one on either side of the front door. They are in large containers. I water them daily (in AL) and fertilize once a month. About 2 weeks ago, one started to look droppy, and now leaves are dying. The one doing well gets pretty much all sun and the dying one gets late morning and afternoon sun light. Any ideas?
One of My Mandevillas Appears to Be Dying
It may be that the one that is getting less sunlight, doesn't need as much water as the other one, and its soil is staying too wet, thus encouraging root diseases. Use a moisture meter or wooden probe to test the amount of moisture in the soil near the bottom of the pot, and cut back on water if the soil seems too wet. It should feel damp, but not drippy or oozy. This article may offer some insights: https://www.gardeningknowhow.com/ornamental/vines/mandevilla/mandevilla-plant.htm