Plastic garden flower pots can last for several years when placed outside, but their lifespan can vary depending on various factors such as the quality of the plastic, exposure to sunlight, temperature fluctuations, and general wear and tear. High-quality plastic flower containers made from UV-resistant materials are more likely to withstand outdoor conditions for longer periods. However, it's a good idea to regularly inspect your fancy plastic flower pots for any signs of damage or deterioration and replace them as needed to ensure the health and longevity of your plants.