The answer to 'why is my flower bed yellowing' is that there are several common causes, including nutrient deficiency, disease, or environmental stress. Yellowing leaves can be a sign of a lack of nitrogen, iron, or other essential nutrients in the soil. It can also indicate a fungal disease or pest infestation affecting the plants. Additionally, factors like too much or too little water, excessive sun exposure, or cold temperatures can cause flower beds to yellow.
To troubleshoot the issue, start by inspecting the plants closely for signs of disease or pests. Check the soil moisture and fertility levels, and consider amending the soil with compost or a balanced fertilizer if needed. If the problem persists or you're unsure of the cause, it's best to consult a local landscaping professional who can diagnose the issue and recommend the appropriate treatment.