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Mulching Police on Patrol!

Fine Mulch

Coarse Mulch

To mulch or not to mulch?  That is the question!  Mulching is great for your garden and believe it or not, it’s actually required by law.  Don’t worry – if you do not mulch you will not be taken to “non-mulchers” jail or even fined, but mulching is an important part of water conservation and is included in the 1990 Water Conservation in Landscaping Act (AB325). This act was designed to encourage backyard gardeners to abide by seven basic principles of water conservation, one of which is mulching.

Mulch is defined as any material applied to the surface of the soil to improve the texture. Mulching reduces water evaporation from soil by 50 percent, thus reducing the need to frequently water. It also protects soil from erosion, suppresses weeds by 2/3 by blocking them from sunlight and inhibiting their ability to grow, and also serves as a soil conditioner. Earthworms, which aerate the soil and leave castings (worm poop) that act as a high-quality fertilizer, are also very much attracted to mulch.

Mulching also reduces crusting and soil compaction (that’s when the soil dries out and cracks). It does this by lowering the soil temperature by almost 10 degrees. In the winter it can have the opposite effect by contributing to warming of the soil, protecting it from those frosty winter evenings.

Mulch is usually applied to vegetable gardens once the soil has warmed up; around spring time or a little later. The coarser the material the deeper the mulch should go. The California Master Gardener’s Handbook suggests the mulch depth should be around 1-3 inches for finer materials, such as sawdust and grass clippings, and for coarser materials, like bark or straw or even shredded plant matter, use 3-6 inches. But be careful not to put mulch too close to the stem of plants or the trunks of trees as it may retain too much water and have damaging effects on the plant, like crown rot.

Thank you Shirley Porter, Nevada County Master Gardener, for providing us with this information from The Curious Gardener newsletter published by Nevada and Placer County UC Cooperative Extension.  Their website is filled with great information, classes and events.  Check it out here!

Example of Mulching Several Inches From Tree Trunk

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2 Responses to “Mulching Police on Patrol!”

  1. In So California, I find it helpful to first add the fine, organic mulch like from your compost bin and then a layer of the coarser bark. That way the sun can dry out the bark instead of the rich compost.

  2. Absolutely! Great tip! Thank you Kathy!