When should I split irises to ensure optimal growth and flourishing blooms? Is there a specific time of year that is preferable for this task, or does it depend on the particular variety of iris in question? As the seasons shift, do the signs in the irises themselves offer clues as to when they are ready for division? What indicators should I look for, such as overcrowded rhizomes, diminished flowering, or even a decline in overall health? Are there environmental factors, like soil temperature and moisture, that could influence the timing of this horticultural endeavor? Beyond these considerations, does the local climate play a role, perhaps necessitating adjustments in the timeline for different regions? And lastly, could the method of splitting irises vary according to the specific conditions? What best practices should I adhere to while performing this task to ensure the longevity and vibrancy of my irises?