Dethatching is the removal of the excess matted dead grass that builds up over time. This can be done manually with a rake or with a power machine. You should dethatch a lawn when the thatch layer is more than ½ inch thick.
Dethatching encourages growth by allowing air, water and fertilizer to reach the roots.
The best time to dethatch a cool season lawn is from late August through early October. You want to do this while your lawn is still growing vigorously and while there is time for it to recover before going dormant for the winter.
Fall is an ideal time because weed seeds are not germinating. Your lawn then has time to thicken up before weed seeds can become a problem.
Early spring is another good time to dethatch before the lawn growth has really begun and it is sometimes easier to get at the thatch.
Brought to you by your Portland sod company, Far West Turf Farm and Nursery