In general, don’t be a bagger! At least not all the time. Mulching the clippings will feed nutrients back into the lawn and keep your lawn greener and healthier all season. The grass blade is made of 85% water and will quickly decompose into your lawn.
When should you bag? Bag the clippings if the lawn happened to grow to long. It is important not to leave behind clumps of clippings that will smother areas.
Ideally you should only remove 1/3 of the grass blade per mowing. Mowing too much off at once will stress the lawn and cause discoloration.