Understanding mulches used for landscaping

Landscaping Mulch
Characteristics of wood mulch and other products used when landscaping garden beds

When considering which type or color of mulch to use in your landscape beds it really helps to have photos of the various products. This page will assist you in the selection of mulch you like, even though these photos will vary slightly from the actual mulch products you find at your local landscape supply.

Natural hardwood mulches

Mulches fade and breakdown, but fading seems to be the leading reason for homeowners to re-mulch their beds.

Single shredded mulch
Typically a mixture of tree bark and wood that is run through a tub grinder one time.

Double shredded mulch
Typically a mix of tree bark and wood that is run through a tub grinder twice.

Triple shredded mulch
Typically a mix of tree bark and wood that is run through a tub grinder three times.
Single?  Double??  Triple Mulch???

The more times a wood mulch is ground, the finer and more uniform the texture becomes. The finer ground mulches break down faster, not lasting as long as coarser ground mulches.

Planning your home mulching project
  1. Plan to re-mulch every year, or every two years if you want to stretch things a bit. The sun “bleaches out” most older wood mulches, making them them far less attractive over time.
  2. Fertilize plants in your shrub bed with a nitrogen fertilizer before applying mulch. This will counteract nitrogen depletion in the soil which occurs when wood mulches break down.
  3. It’s detrimental to plants if mulch becomes too thick (over 3 – 4 inches or 7 – 10 centimeters deep), and weeds will become more of a problem if mulch has broken down and becomes too thin (under one-half inch). Wood-based mulches can also ‘crust over’ and repel water.
  4. Wood mulches on top of landscape fabric or black plastic break down more slowly since they aren’t in contact with microbes in the soil. Therefore, this type of artificial barrier reduces the positive benefits of decaying mulch adding organic matter to soil.
  5. Bob recommends spreading shredded wood mulches at a depth of 1-1/2 to 2 inches ( 4 to 5 centimeters) with annual applications. 1 cubic yard (3/4 cubic meter) of double-shredded hardwood mulch typically covers 150 square feet at Bob’s recommended depth of 1-1/2 inches.

! Precautions with Mulch !

Avoid dark-colored “hot” mulch that has become toxic to plants through anaerobic decomposition in a large pile. You can easily identify this type of “killer” mulch from its strong ammonia-like odor. If you insist on using it, try spreading it out (away from plants) for a couple days to let the fumes dissipate, and water it down right after spreading it in landscape beds. Bob recommends avoiding it altogether after seeing it “fry” annual flower$ and “burn” lawns several inches from the edge of shrub beds. Don’t get “burned!”

Mulch (of any kind including decorative stone) can create home insect problems, so pest control professionals Bob has interviewed recommend not having mulch within a few feet of your home’s foundation. Carpenter ants love wet, decaying wood. Termites can also be a problem.

Dyed mulches can stain a concrete driveway so plan your dyed mulch deliveries accordingly.

Dyed wood mulches

Dyed mulches are more expensive but hold their color longer than natural mulches. Some consumers are concerned about the source of the “waste wood” (shredded pallets?) used in some dyed mulches on the market. Remember, the dye can stain things and the color can wash-off (especially the chunkier mulches), so try to work with dyed mulches in periods of dry weather.

Dyed brown mulch
Shredded bark/wood mulch that has been dyed brown. This is Bob’s favorite color since it looks the most natural in landscape beds.

Dyed black mulch
Shredded bark/wood mulch that has been dyed black. Contrasts with flowers and other plant colors the most.

Dyed red mulch
Shredded bark/wood mulch that has been dyed red. Makes a bold landscape statement all by itself.
How much mulch do I need?

Landscaping products purchased in bulk are typically sold by volume or weight. Mulch products are sold by the cubic foot or cubic yard, so how much is in one cubic yard?

  1. Mulch is usually sold by “the yard” (cubic yard)
    1 cubic yard contains 27 cubic feet or 0.76 cubic meters.
    3 feet x 3 feet x 3 feet = 27 cubic feet or 1 cubic yard.
    1 cubic yard of double-shredded hardwood mulch typically covers 150 square feet at Bob’s recommended depth of 1-1/2 inches (4 centimeters). If you are mulching every year, thicker layers can create an undesirable mulch build-up. Keep mulch away from tree trunks. 
  2. Soil and stone are usually sold by the ton
    1 ton = 2,000 pounds (lbs.) or 907 kilograms.
    Soil volume vs. weight: 1 cubic yard of soil is approximately equal to 1 ton, depending on the moisture content and the particular type of soil.
Coverage of Shredded Mulch per 100 square feet

Coverage can vary greatly due to the type of mulch used. As a general guide, below are the amounts of dry, double-shredded hardwood mulch that were required on projects, where 1 cubic yard covers 150 square feet at Bob’s recommended depth of 1-1/2 inches.

Depth in inches
Cubic yards needed per 100 square feet

1/2 inch: 0.22 yard

1 inch: 0.44 yard

1-1/2 inches: 0.66 yard

2 inches: 0.88 yard

2-1/2 inches: 1.10 yards

3 inches: 1.32 yards

3-1/2 inches: 1.54 yards

4 inches: 1.76 yards

Other types of mulch
Bark nuggets 
Nuggets last longer than shredded hardwood mulches and are available in different sized nuggets. Brown color with a pleasant pine odor.

Pine straw 
Pine needle mulch is typically seen more often in southern United States landscapes. Can be a fire hazard with lit cigarette butts.

Cypress mulch 
Cypress mulches have a distinctive orange color and fresh odor. Resist decay better than hardwood mulches.

Mushroom manure or Mushroom Compost
Mushroom manure (or mushroom compost) is typically used for mulching flower beds, topdressing seeded lawns or mixing with soil to add organic matter. It is only available in certain regions where mushrooms are grown.

Playground mulch
Special grinds and blends of hardwood mulch are considered playground mulches and used around playground equipment to soften falls.

Artillery fungus – What causes those tar spots on houses?

Dyed mulch – Popular mulch that comes in choice of colors

Decorative gravel – An alternative to wood mulches

Quantity calculations – Figure out how much you need!