Besides looking neat and clean, installing mulch on your property has many other positives. We found a great resource from Colorado State University that clearly explains the benefits and how to correctly use mulch. (below referenced: Interested in adding mulch to your property? Call HRL!

The term mulch refers to a material placed on the soil surface.  A soil amendment refers to any material mixed into soil.

Benefits of Mulching

Depending on materials used, mulches have many benefits, including the following:

  • Reduces evaporation from soil surface, cutting water use by 25-50%
  • Organic mulches promote soil microorganism activity, which in turn, improves soil tilth and helps lessen soil compaction.  For additional details, refer the CMG GardenNotes #211, The Living Soil.
  • Stabilizes soil moisture
  • Prevents soil compaction
  • Controls weeds, which rob soil moisture
  • Moderates soil temperature extremes
  • Controls erosion
  • Gives a finished look, improving aesthetic quality

Edging and Soil Grade

It is a common practice to add mulching materials above grade level.  Without a defined edge, the mulch may readily spread off the bed onto lawns or sidewalks, creating a mowing or trip hazard. 

[Figure 1]

mulch and grading
Figure 1.  Mulch added above grade spills out onto the lawn or sidewalk.


An effective alternative is to drop the soil level on the mulch bed 3 inches so the top of the mulch is at grade level.  However, ensure that the mulched bed does not fill with water draining from higher areas.  [Figure 2]

mulch and edging
Figure 2.  To keep mulch in place, drop the soil level in the mulch bed so the top of the mulch is at the grass or sidewalk level.


An effective alternative is to round down the soil level along the edge of the bed.  This gives a nice finished edge at grade level and creates a raised bed effect for the flowerbed.  [Figure 3]

mulch and edging
Figure 3.  An alternative is to taper the soil level along the edge of the bed.


Wood/Bark Chip Mulch


Wood or bark chip mulch is great around trees, shrubs, perennials, and small fruits.  [Figure 4]  A wood/bark chip mulch creates a favorable environment for earthworms and soil microorganisms.  Over time, this helps reduce soil compaction.  For additional details, refer to the CMG GardenNotes #212, The Living Soil and #218, Earthworms.

In perennial and shrub beds, wood/bark chips can reduce the need for irrigation by as much as 50%.  Mulching materials that mesh together are more effective at reducing water evaporation from the soil.  Under acute water restrictions, gardeners with wood/bark chip mulch have been incorrectly accused of illegally irrigating because their plants are still faring well, compared to the neighbors!

When placed on the soil surface as mulch, wood/bark chips do not tie-up soil nitrogen.  However, incorporating wood/bark chips into a soil can create a nitrogen deficiency due to a carbon-to-nitrogen imbalance, and can interfere with seedbed preparation.  It takes ten or more years for chips to decompose in a typical soil.  The use of fine chips or sawdust as mulch can tie-up soil nitrogen and can decrease soil oxygen levels.

Wood/bark chips are not recommended in vegetable or annual flowerbeds where the soil is routinely cultivated to prepare a seedbed.

wood chip mulch
Figure 4.  Wood/bark chip mulch in the perennial and shrub bed greatly enhances soil tilth over time.