Hello I have had the Madevilla vine plant for years in a flower pot for years. I buy them and plant them news each year. We put the wet ones this time and added those to the back ones in the front of pink they are doing wonderful. The ones in the back are red one already dried out and died the second one now is has flowering but the plans are yellowing is it going on it looks like if it\'s lack of water but that\'s not the issue. Any recommendations?
It does look like the container size is small for the plant size.
You may have overcrowded roots. This can cause the plant to die out. They can't take up water and nutrients are lacking with little soil content.