How Often Should You Replace Mulch?

How often should you replace mulch?

There is no hard and fast rule, but most people agree that it is important to maintain your mulch by replacing or replenishing it periodically, at least every five to six years. 

Organic mulches generally last five to six years, but several factors can cause you to have to replace or replenish earlier. These factors include the type of mulch used – wood chips, bark mulch, compost, straw, untreated grass clippings, river rocks, gravel, or any number of materials, weather conditions, rainfall, sun exposure, etc. 

What Is Mulch?

Mulch is any material – bark, compost, straw, gravel, etc. – added to the soil’s surface to help suppress weeds, stabilize soil temperatures, and improve soil moisture and garden appearance. 

Mulch is a great gardening tool – helping block sunlight and prevent weed plants from emerging through the soil.

Extra steps that can be taken to help prevent weeds from growing through mulch include:

  • Using landscape fabric over soil and covering with a layer of mulch helps to block out sunlight and prevent weed growth.
  • Spraying weeds with vinegar mixed with a small amount of dish soap is a safe, all-natural, and inexpensive alternative to most herbicides on weeds that have already begun to grow through the mulch.
  • Defining the garden with deep edges can discourage weed roots from making their way under the mulch. It also helps save time, money, and energy that you would later have spent pulling weeds.

Know When To Replace Your Mulch

Signs of decomposition, soil erosion, and discoloration are hints your mulch may be due to be replaced or replenished. These signs can be visible from one to two years after mulching. Eventually, all mulch will decompose and cease to provide the benefits it was intended for. Organic mulches provide nutrients to your soil, aiding moisture retention, and protecting the soil. As it decomposes or reduces in depth, it is more likely problems with soil erosion and weeds may become more visible.

Once mulch has decomposed into the soil and released its nutrients, it will need to be replaced.

Failure to replace the mulch will result in the loss of added nutrients provided to your plants.

Decomposed mulch loses consistency and stops performing many of its functions. Once degraded to a certain level, the soil retains less moisture. As a result, weeds and erosion will begin to be problematic.

Some undyed mulches may start to turn gray after about a year. It’s still effective, just not attractive. People often choose to replace all or some of the faded mulch to improve landscaping aesthetics. Dyed mulches might hold their color longer, but it is important to make sure you learn how it has been dyed. Cheaper mulches that use artificial processes to color them can impact the earth negatively because the dye penetrates the ground. As a result, dyed mulches are generally replaced annually. 

How Much Mulch You’ll Need

Save time and money by knowing exactly how much mulch you need to use. Follow the steps below to determine how much mulch you will need in cubic yards before heading to the store or ordering online. 

  1. Measure the length and width of your garden space in feet and multiply those figures together to determine the square footage of the area. Repeat this step for all of the different sections of your yard. Once you’ve finished calculating the square footage of each section, add all those figures together to get the total square footage that will need to be covered with mulch.
  2. Determine how deep you want the layer of mulch to be. In most flowerbeds and vegetable gardens, two to three inches tend to be the ideal depth. You may want to consider using up to six inches of mulch if you need heavy weed or grass suppression.
  3. Calculate the total area by multiplying the square footage by the depth you want the mulch to be. Divide the answer by 324, because one cubic yard of mulch will cover 324 square feet, then round the result to the nearest whole number to find out how many cubic yards of mulch you will need to use.

Two to four inches thick throughout flower beds are ideal. Since mulch decomposes over time, make sure to apply an inch more mulch than you want to end up with. Applying mulch too thinly will mean that the flowers will not receive the same level of benefits from using mulch, such as moisture retention and weed suppression.

Maintaining Your Mulch

Check the mulch at the beginning of Spring and see what condition it’s in. If it looks the same as it did when you first laid it you may not need to replace it. If it has degraded into smaller pieces, it is probably best to replace it.

Spring and Fall are the best times to check to see if your mulch needs replenishing. Mulch depth should be maintained at two to three inches thick. Make sure mulch is not up against trees, as it invites pests and rodent activity and encourages disease.

Replenish Or Replace?

It isn’t always necessary to fully replace the existing mulch. Replenishing the material may often be sufficient. 

Old mulch can bunch up so before applying new mulch, rake the old mulch so it is even along the landscape. Apply the new mulch on top. Replenishing can be done every one to two years, providing untold benefits to your plants. This also allows the old mulch to add any remaining nutrients to the ground, as well as save you the time and effort of removing the old mulch.

Should you decide to change the kind of mulch you use in the garden, for example – from bark to gravel – it would then be best to totally replace the existing kind to give yourself a fresh start, and also to ensure that it retains aesthetic appeal. 

Top-quality mulch will look great all season, protect your plants, trees, and shrubs and keep away weeds.