Is my vinca plant dying?
The soil is moist but not too moist, it’s wilting slightly, and the leaves are discolored a little. Any thoughts on what I’m doing wrong or what’s wrong with the plant?
Certified GKH Gardening Expert
This is, certainly, the start of a fungal infection. The soil should be let to dry out down to at least two inches. Leaving the soil consistently moist will often lead to infection. It will also appreciate some shade during the day if it does not get any.
Also, it is important that the container has plenty of drain holes. If there is not enough drainage, it can appear dry on top but water logged down further, which will cause infection.
At this point, I would recommend dolomitic lime and wettable sulfur. Sulfur is a good antimicrobial, and dolomitic lime will repair the pH from the action of the sulfur.
This will, usually, kill off an infection as long as it is not something incurable such as Mosaic Virus.
This article will give you more information on the care of these plants: https://www.gardeningknowhow.com/ornamental/groundcover/periwinkle/growing-periwinkle.htm