The answer to 'flower bed yellowing' is that there are several common causes, including nutrient deficiencies, overwatering, disease, or pest infestations. Symptoms may include leaves turning yellow or pale green, with the yellowing often starting at the outer edges of the leaves and gradually spreading inward. To solve the issue, you'll need to diagnose the underlying cause and take appropriate action.
If the yellowing is due to a nutrient deficiency, you can apply a balanced fertilizer or amend the soil with compost or other organic matter. Overwatering can be addressed by adjusting your watering schedule and ensuring proper drainage. Diseases and pests may require the use of targeted treatments, which could involve the application of fungicides or insecticides. In some cases, it may be best to consult a professional landscaper or horticulturist to properly diagnose and treat the problem.