Grass clippings will always be a part of lawn care. Lawns grow at different rates depending on environmental conditions and management practices. Grass clippings an inch or less in length filter down to the soil surface and decompose relatively quickly.

Clippings are a valuable source of nutrients. University of Minnesota soil test recommendations call for less nitrogen fertilizer if clippings are returned to the lawn. Also, the addition of organic matter in the form of clippings may help to improve the status of your soil if it is sandy or low in organic matter.

Returning clippings to the lawn does not normally contribute to increased thatch formation. Thatch is a layer of undecomposed organic matter that builds up between the soil surface and the actively growing green vegetation. The major factors contributing to thatch development are

• excessive nitrogen fertilization
• infrequent mowing
• low soil oxygen levels
• soil compaction
• over mulching

While leaving clippings on the lawn is recommended, certain instances make the practice inadvisable. Following are some exceptions to the rule:

• If the lawn is heavily infested with certain leaf diseases, removing clippings may help reduce disease severity.
• If the lawn must be mowed when wet, or if the grass has become too tall, clippings can mat together and smother the grass
• If your mower is unsafe to operate without a bagging attachment, the bag should be left in place.

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