To leave the clippings or bag the clippings, that is a question we get on the regular.
We always recommend mulching the grass clippings and leaving them on your lawn. This process is known as grasscycling and is strongly recommended for a number of reasons - it's great for your lawn!!
Grass clippings will quickly break down, returning nutrients to the soil becoming a natural fertilizer adding much needed nitrogen and water back to your lawn.
Clippings help protect the soil and increase soil health by keeping moisture in the ground - very helpful as we get closer to the warmer days of summer. This allows the lawn to be healthier with less watering required to keep it lush and green
Both of the above reasons help your grass grow greener, healthier and thicker which helps with weed control but not giving the weeds as much opportunity/space to grow.
The only caution we have is don't let your grass get too long in between mows as the clippings will pile up and take longer to decompose leaving little piles of grass everywhere. If you end up having to go a little long between mowing sessions you can lightly rake to break up the piles and also consider removing some of the clippings and popping them into your green box.
For more information check out the City of Calgary, they also agree!