For regular mat maintenance and routine cleaning, we recommend wiping your mat down with a barely-damp cloth on a weekly basis. If you have a vigorous practice, or are doing hot yoga, we recommend doing so after each use.
The really important thing is to NEVER use alcohol, petroleum based solvents or high concentration essential oils (lavender, tea tree, etc.) on your mat. Unfortunately these cleaning products adversely impact the natural rubber in the mats, causing it to break down and dry out. Excessive essential oils also may cause your mat to become slippery. We have found that many yoga mat sprays and natural cleaners on the market do have high concentrations of such essential oils. Never use any brand of dish soap (even diluted with water) on your yoga mat. This will cause your mat to lose it's "sticky" quality and cause it to become slippery. Never wash your mat in the laundry washing machine. Never submerge your mat in water.