The answer to 'why is my patio overgrown' is that your patio has likely become overgrown due to a combination of factors, such as lack of regular maintenance, excessive plant growth, and environmental conditions. Patios can easily become overrun with weeds, moss, and other unwanted vegetation if they are not properly cared for on a regular basis.
Some common causes of an overgrown patio include allowing weeds and grass to take root, not regularly sweeping or clearing debris, and not applying the appropriate herbicides or treatments to prevent plant growth. Additionally, environmental factors like heavy rainfall, shade, or poor drainage can contribute to the overgrowth on your patio. To address an overgrown patio, you'll need to take a multi-faceted approach that includes weeding, cleaning, and potentially applying specialized treatments.