The answer to 'why is my flower bed disease' is that your flower bed may be experiencing a fungal or bacterial disease. Common symptoms include discolored, wilting, or rotting flowers and leaves. Potential causes include overwatering, poor soil drainage, excessive shade, or a pest infestation.
To address the issue, start by inspecting the bed closely for signs of disease, such as spots, mold, or insects. Adjust your watering and sunlight levels as needed. You may also need to treat the soil with a fungicide or remove and replace any severely infected plants. If the problem persists or worsens, it's best to call in a professional landscaper or horticulturist to properly diagnose and treat the issue.