How often should I fertilize my grass to achieve a verdant and luxuriant lawn that not only enhances the aesthetic appeal of my outdoor space but also supports the health of the turf? What considerations should I take into account regarding the type of grass I have, the climate in my region, and the specific nutrient requirements it demands throughout the changing seasons? Is there a particular schedule I should adhere to, perhaps aligning with peak growth periods in spring and fall? Additionally, should I be mindful of variations in fertilization techniques, such as granular versus liquid applications, and their respective impacts on grass vitality? Could the frequency of fertilization also be influenced by environmental factors such as rainfall, temperature fluctuations, and soil composition? What are the signs that my lawn might be under-fertilized or over-fertilized, and how can I strike the perfect balance to maintain optimal grass health without causing harm?