The answer to 'why is my drainage system dying plants' is that a malfunctioning drainage system can cause waterlogged soil, which deprives plant roots of oxygen and leads to plant decline and death. Common causes include clogged drains, improper drainage slope, or damaged drainage pipes.
Symptoms of a failing drainage system include standing water, wilting or yellowing plants, and fungal growth. To address this, you'll need to inspect the drainage system, clear any blockages, and ensure proper drainage flow and slope. In some cases, you may need to install new drainage pipes or upgrade the system.