Potted plants are dying and I’d like to know what’s wrong with them

Question

I have several potted tomato plants (I live in a 4th floor balcony apartment) that were planted 4 months ago that were beautiful and healthy and recently the leaves have begun yellowing. They then withered and the plants died. And now, several other plants that are quite young are beginning to wilt and die: watermelon plants, squash plants, thyme and cilantro. They almost seem to rot at the base or root. I haven’t changed how I water or fertilize the plants and there doesn’t seem to be any insect or larvae infestation. I’ve planted new seeds only to have them grow healthy for a few weeks and then wither. What would be causing this? What should I do differently?

Answer 1

They may not be draining well enough and the water in the soil is literally rotting the stems and roots away. This article will help you determine if it is root rot:
https://www.gardeningknowhow.com/plant-problems/disease/treating-root-rot-gardening-tips-for-housplants.htm

You may want to change your watering schedule so that you water when the top of the soil is dry. If you are having drainage issues, this might help offset them.